diff --git a/addons/bus/__manifest__.py b/addons/bus/__manifest__.py
index 56ae574ebab..96fcf0dbcde 100644
--- a/addons/bus/__manifest__.py
+++ b/addons/bus/__manifest__.py
@@ -16,6 +16,7 @@
             'bus/static/src/js/longpolling_bus.js',
             'bus/static/src/js/crosstab_bus.js',
             'bus/static/src/js/services/bus_service.js',
+            'bus/static/src/js/services/legacy/*.js',
         ],
         'web.qunit_suite_tests': [
             'bus/static/tests/*.js',
diff --git a/addons/bus/static/src/js/services/legacy/legacy_bus_service.js b/addons/bus/static/src/js/services/legacy/legacy_bus_service.js
new file mode 100644
index 00000000000..f9d42c3fb2c
--- /dev/null
+++ b/addons/bus/static/src/js/services/legacy/legacy_bus_service.js
@@ -0,0 +1,13 @@
+/** @odoo-module **/
+
+import { registry } from '@web/core/registry';
+
+const { Component } = owl;
+
+export const legacyBusService = {
+    start() {
+        return Component.env.services.bus_service;
+    },
+};
+
+registry.category('services').add('legacy_bus_service', legacyBusService);
diff --git a/addons/calendar/static/tests/helpers/mock_server.js b/addons/calendar/static/tests/helpers/mock_server.js
index 4d1899b322f..3e6be594327 100644
--- a/addons/calendar/static/tests/helpers/mock_server.js
+++ b/addons/calendar/static/tests/helpers/mock_server.js
@@ -2,10 +2,13 @@
 
 // ensure mail override is applied first.
 import '@mail/../tests/helpers/mock_server';
-import MockServer from 'web.MockServer';
+
+import { patch } from '@web/core/utils/patch';
+import { MockServer } from '@web/../tests/helpers/mock_server';
+
 import { datetime_to_str } from 'web.time';
 
-MockServer.include({
+patch(MockServer.prototype, 'calendar', {
     //--------------------------------------------------------------------------
     // Private Mocked Methods
     //--------------------------------------------------------------------------
diff --git a/addons/calendar/static/tests/systray_activity_menu_tests.js b/addons/calendar/static/tests/systray_activity_menu_tests.js
index 3a0bcdd50f8..c8afcb848b8 100644
--- a/addons/calendar/static/tests/systray_activity_menu_tests.js
+++ b/addons/calendar/static/tests/systray_activity_menu_tests.js
@@ -33,9 +33,7 @@ QUnit.test('activity menu widget:today meetings', async function (assert) {
     ]);
     legacySystrayItems.push(ActivityMenu);
     registerCleanup(() => legacySystrayItems.pop());
-    const { wowlEnv: env } = await start({
-        hasWebClient: true,
-    });
+    const { env } = await start();
     assert.containsOnce(document.body, '.o_mail_systray_item', 'should contain an instance of widget');
 
     await testUtils.dom.click(document.querySelector('.dropdown-toggle[title="Activities"]'));
diff --git a/addons/hr/static/tests/m2x_avatar_employee_tests.js b/addons/hr/static/tests/m2x_avatar_employee_tests.js
index ab8863d7cdf..b3a6c2197ca 100644
--- a/addons/hr/static/tests/m2x_avatar_employee_tests.js
+++ b/addons/hr/static/tests/m2x_avatar_employee_tests.js
@@ -6,11 +6,10 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import FormView from 'web.FormView';
-import KanbanView from 'web.KanbanView';
-import ListView from 'web.ListView';
+import { makeFakeNotificationService } from "@web/../tests/helpers/mock_services";
+
 import { Many2OneAvatarEmployee } from '@hr/js/m2x_avatar_employee';
-import { dom, mock } from 'web.test_utils';
+import { dom } from 'web.test_utils';
 
 QUnit.module('hr', {}, function () {
     QUnit.module('M2XAvatarEmployee', {
@@ -40,17 +39,20 @@ QUnit.module('hr', {}, function () {
             { employee_id: hrEmployeePublicId2 },
             { employee_id: hrEmployeePublicId1 },
         ]);
-        await start({
-            hasView: true,
-            View: ListView,
-            model: 'm2x.avatar.employee',
-            arch: '<tree><field name="employee_id" widget="many2one_avatar_employee"/></tree>',
+        const views = {
+            'm2x.avatar.employee,false,list': '<tree><field name="employee_id" widget="many2one_avatar_employee"/></tree>',
+        };
+        const { openView } = await start({
             mockRPC(route, args) {
                 if (args.method === 'read') {
                     assert.step(`read ${args.model} ${args.args[0]}`);
                 }
-                return this._super(...arguments);
             },
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            views: [[false, 'list']],
         });
 
         assert.strictEqual(document.querySelector('.o_data_cell span').innerText, 'Mario');
@@ -120,13 +122,9 @@ QUnit.module('hr', {}, function () {
         const resUsersId1 = pyEnv['res.users'].create({ partner_id: resPartnerId1 });
         const hrEmployeePublicId1 = pyEnv['hr.employee.public'].create({ user_id: resUsersId1, user_partner_id: resPartnerId1 });
         pyEnv['m2x.avatar.employee'].create({ employee_id: hrEmployeePublicId1, employee_ids: [hrEmployeePublicId1] });
-        await start({
-            hasView: true,
-            View: KanbanView,
-            model: 'm2x.avatar.employee',
-            data: this.data,
-            arch: `
-                <kanban>
+        const views = {
+            'm2x.avatar.employee,false,kanban':
+                `<kanban>
                     <templates>
                         <t t-name="kanban-box">
                             <div>
@@ -135,6 +133,13 @@ QUnit.module('hr', {}, function () {
                         </t>
                     </templates>
                 </kanban>`,
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            views: [[false, 'kanban']],
         });
 
         assert.strictEqual(document.querySelector('.o_kanban_record').innerText.trim(), '');
@@ -148,41 +153,36 @@ QUnit.module('hr', {}, function () {
         const pyEnv = await startServer();
         const hrEmployeePublicId1 = pyEnv['hr.employee.public'].create({ name: 'Mario' });
         const m2xHrAvatarUserId1 = pyEnv['m2x.avatar.employee'].create({ employee_id: hrEmployeePublicId1 });
-        const { widget } = await start({
-            hasView: true,
-            View: FormView,
-            model: 'm2x.avatar.employee',
-            data: this.data,
-            arch: '<form><field name="employee_id" widget="many2one_avatar_employee"/></form>',
+        const views = {
+            'm2x.avatar.employee,false,form': '<form><field name="employee_id" widget="many2one_avatar_employee"/></form>',
+        };
+        const { openView } = await start({
             mockRPC(route, args) {
                 if (args.method === 'read') {
                     assert.step(`read ${args.model} ${args.args[0]}`);
                 }
-                return this._super(...arguments);
             },
-            res_id: m2xHrAvatarUserId1,
+            serverData: { views },
             services: {
-                notification: {
-                    notify(notification) {
-                        assert.ok(
-                            true,
-                            "should display a toast notification after failing to open chat"
-                        );
-                        assert.strictEqual(
-                            notification.message,
-                            "You can only chat with employees that have a dedicated user.",
-                            "should display the correct information in the notification"
-                        );
-                    },
-                },
+                notification: makeFakeNotificationService(message => {
+                    assert.ok(
+                        true,
+                        "should display a toast notification after failing to open chat"
+                    );
+                    assert.strictEqual(
+                        message,
+                        "You can only chat with employees that have a dedicated user.",
+                        "should display the correct information in the notification"
+                    );
+                }),
             },
         });
-        mock.intercept(widget, 'call_service', (ev) => {
-            if (ev.data.service === 'notification') {
-                assert.step(`display notification "${ev.data.args[0].message}"`);
-            }
-        }, true);
 
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            res_id: m2xHrAvatarUserId1,
+            views: [[false, 'form']],
+        });
         assert.strictEqual(document.querySelector('.o_field_widget[name=employee_id]').innerText.trim(), 'Mario');
 
         await dom.click(document.querySelector('.o_m2o_avatar > img'));
@@ -206,21 +206,23 @@ QUnit.module('hr', {}, function () {
         const m2xAvatarEmployeeId1 = pyEnv['m2x.avatar.employee'].create(
             { employee_ids: [hrEmployeePublicId1, hrEmployeePublicId2] },
         );
-        await start({
-            hasView: true,
-            View: FormView,
-            model: 'm2x.avatar.employee',
-            data: this.data,
-            arch: '<form><field name="employee_ids" widget="many2many_avatar_employee"/></form>',
+        const views = {
+            'm2x.avatar.employee,false,form': '<form><field name="employee_ids" widget="many2many_avatar_employee"/></form>',
+        };
+        const { openView } = await start({
             mockRPC(route, args) {
                 if (args.method === 'read') {
                     assert.step(`read ${args.model} ${args.args[0]}`);
                 }
-                return this._super(...arguments);
             },
-            res_id: m2xAvatarEmployeeId1,
+            serverData: { views },
         });
 
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            res_id: m2xAvatarEmployeeId1,
+            views: [[false, 'form']],
+        });
         assert.containsN(document.body, '.o_field_many2manytags.avatar.o_field_widget .badge', 2,
             "should have 2 records");
         assert.strictEqual(document.querySelector('.o_field_many2manytags.avatar.o_field_widget .badge img').getAttribute('data-src'),
@@ -261,19 +263,22 @@ QUnit.module('hr', {}, function () {
         pyEnv['m2x.avatar.employee'].create(
             { employee_ids: [hrEmployeePublicId1, hrEmployeePublicId2] },
         );
-        await start({
-            hasView: true,
-            View: ListView,
-            model: 'm2x.avatar.employee',
-            arch: '<tree><field name="employee_ids" widget="many2many_avatar_employee"/></tree>',
+        const views = {
+            'm2x.avatar.employee,false,list': '<tree><field name="employee_ids" widget="many2many_avatar_employee"/></tree>',
+        };
+        const { openView } = await start({
             mockRPC(route, args) {
                 if (args.method === 'read') {
                     assert.step(`read ${args.model} ${args.args[0]}`);
                 }
-                return this._super(...arguments);
             },
+            serverData: { views },
         });
 
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            views: [[false, 'list']],
+        });
         assert.containsN(document.body, '.o_data_cell:first .o_field_many2manytags > span', 2,
             "should have two avatar");
 
@@ -330,12 +335,9 @@ QUnit.module('hr', {}, function () {
         pyEnv['m2x.avatar.employee'].create(
             { employee_ids: [hrEmployeePublicId1, hrEmployeePublicId2] },
         );
-        await start({
-            hasView: true,
-            View: KanbanView,
-            model: 'm2x.avatar.employee',
-            arch: `
-                <kanban>
+        const views = {
+            'm2x.avatar.employee,false,kanban':
+                `<kanban>
                     <templates>
                         <t t-name="kanban-box">
                             <div>
@@ -350,14 +352,20 @@ QUnit.module('hr', {}, function () {
                         </t>
                     </templates>
                 </kanban>`,
+        };
+        const { openView } = await start({
             mockRPC(route, args) {
                 if (args.method === 'read') {
                     assert.step(`read ${args.model} ${args.args[0]}`);
                 }
-                return this._super(...arguments);
             },
+            serverData: { views },
         });
 
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            views: [[false, 'kanban']],
+        });
         assert.containsN(document.body, '.o_kanban_record:first .o_field_many2manytags img.o_m2m_avatar', 2,
             "should have 2 avatar images");
         assert.strictEqual(document.querySelector('.o_kanban_record .o_field_many2manytags img.o_m2m_avatar').getAttribute('data-src'),
@@ -390,40 +398,35 @@ QUnit.module('hr', {}, function () {
         const m2xAvatarEmployeeId1 = pyEnv['m2x.avatar.employee'].create(
             { employee_ids: [hrEmployeePublicId1, hrEmployeePublicId2] },
         );
-        const { widget } = await start({
-            hasView: true,
-            View: FormView,
-            model: 'm2x.avatar.employee',
-            arch: '<form><field name="employee_ids" widget="many2many_avatar_employee"/></form>',
+        const views = {
+            'm2x.avatar.employee,false,form': '<form><field name="employee_ids" widget="many2many_avatar_employee"/></form>',
+        };
+        const { openView } = await start({
             mockRPC(route, args) {
                 if (args.method === 'read') {
                     assert.step(`read ${args.model} ${args.args[0]}`);
                 }
-                return this._super(...arguments);
             },
-            res_id: m2xAvatarEmployeeId1,
+            serverData: { views },
             services: {
-                notification: {
-                    notify(notification) {
-                        assert.ok(
-                            true,
-                            "should display a toast notification after failing to open chat"
-                        );
-                        assert.strictEqual(
-                            notification.message,
-                            "You can only chat with employees that have a dedicated user.",
-                            "should display the correct information in the notification"
-                        );
-                    },
-                },
+                notification: makeFakeNotificationService(message => {
+                    assert.ok(
+                        true,
+                        "should display a toast notification after failing to open chat"
+                    );
+                    assert.strictEqual(
+                        message,
+                        "You can only chat with employees that have a dedicated user.",
+                        "should display the correct information in the notification"
+                    );
+                }),
             },
         });
-
-        mock.intercept(widget, 'call_service', (ev) => {
-            if (ev.data.service === 'notification') {
-                assert.step(`display notification "${ev.data.args[0].message}"`);
-            }
-        }, true);
+        await openView({
+            res_model: 'm2x.avatar.employee',
+            res_id: m2xAvatarEmployeeId1,
+            views: [[false, 'form']],
+        });
 
         assert.containsN(document.body, '.o_field_many2manytags.avatar.o_field_widget .badge', 2,
             "should have 2 records");
diff --git a/addons/hr_holidays/static/tests/helpers/mock_server.js b/addons/hr_holidays/static/tests/helpers/mock_server.js
index b34afc79d01..ec536f54fe8 100644
--- a/addons/hr_holidays/static/tests/helpers/mock_server.js
+++ b/addons/hr_holidays/static/tests/helpers/mock_server.js
@@ -1,11 +1,11 @@
-odoo.define('hr_holidays/static/tests/helpers/mock_server.js', function (require) {
-'use strict';
+/** @odoo-module **/
 
-require('@mail/../tests/helpers/mock_server'); // ensure mail overrides are applied first
+import '@mail/../tests/helpers/mock_server'; // ensure mail overrides are applied first
 
-const MockServer = require('web.MockServer');
+import { patch } from "@web/core/utils/patch";
+import { MockServer } from "@web/../tests/helpers/mock_server";
 
-MockServer.include({
+patch(MockServer.prototype, 'hr_holidays', {
     /**
      * Overrides to add out of office to employees.
      *
@@ -25,5 +25,3 @@ MockServer.include({
         return partnerFormats;
     },
 });
-
-});
diff --git a/addons/im_livechat/static/tests/helpers/mock_server.js b/addons/im_livechat/static/tests/helpers/mock_server.js
index ef1bb11e74e..381a44263ef 100644
--- a/addons/im_livechat/static/tests/helpers/mock_server.js
+++ b/addons/im_livechat/static/tests/helpers/mock_server.js
@@ -2,9 +2,10 @@
 
 import '@mail/../tests/helpers/mock_server'; // ensure mail overrides are applied first
 
-import MockServer from 'web.MockServer';
+import { patch } from "@web/core/utils/patch";
+import { MockServer } from "@web/../tests/helpers/mock_server";
 
-MockServer.include({
+patch(MockServer.prototype, 'im_livechat', {
     //--------------------------------------------------------------------------
     // Private
     //--------------------------------------------------------------------------
@@ -12,7 +13,7 @@ MockServer.include({
     /**
      * @override
      */
-    async _performRpc(route, args) {
+    async _performRPC(route, args) {
         if (route === '/im_livechat/get_session') {
             const channel_id = args.channel_id;
             const anonymous_name = args.anonymous_name;
diff --git a/addons/mail/__manifest__.py b/addons/mail/__manifest__.py
index ebe076efca2..ea2236f8764 100644
--- a/addons/mail/__manifest__.py
+++ b/addons/mail/__manifest__.py
@@ -83,11 +83,12 @@
             'mail/static/src/model/*.js',
             'mail/static/src/models/*.js',
             'mail/static/src/public/*',
-            'mail/static/src/services/messaging/messaging.js',
+            'mail/static/src/services/*.js',
             'mail/static/src/utils/*.js',
             # Framework JS
             'bus/static/src/js/*.js',
             'bus/static/src/js/services/bus_service.js',
+            'bus/static/src/js/services/legacy/legacy_bus_service.js',
             'web/static/lib/luxon/luxon.js',
             'web/static/src/core/**/*',
             # FIXME: debug menu currently depends on webclient, once it doesn't we don't need to remove the contents of the debug folder
@@ -122,7 +123,7 @@
             'mail/static/src/components/*/*.scss',
             'mail/static/src/model/*.js',
             'mail/static/src/models/*.js',
-            'mail/static/src/services/*/*.js',
+            'mail/static/src/services/*.js',
             'mail/static/src/webclient/commands/*.js',
             'mail/static/src/widgets/*/*.js',
             'mail/static/src/widgets/*/*.scss',
@@ -150,7 +151,6 @@
         'web.assets_qweb': [
             'mail/static/src/xml/*.xml',
             'mail/static/src/components/*/*.xml',
-            'mail/static/src/widgets/*/*.xml',
         ],
     },
     'license': 'LGPL-3',
diff --git a/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml b/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml
index b6f017fa428..4d92aa4b995 100644
--- a/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml
+++ b/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml
@@ -26,8 +26,8 @@
                     </div>
                     <div class="o-autogrow"/>
                     <div class="o_AttachmentViewer_buttonDownload o_AttachmentViewer_headerItem o_AttachmentViewer_headerItemButton d-flex align-items-center px-3 o_cursor_pointer" t-on-click="attachmentViewer.onClickDownload" role="button" title="Download">
-                        <i class="o_AttachmentViewer_headerItemButtonIcon fa fa-download fa-fw" t-att-class="{ 'o-hasLabel me-2': messaging.device.sizeClass > env.device.SIZES.MD }" role="img"/>
-                        <t t-if="messaging.device.sizeClass > env.device.SIZES.MD">
+                        <i class="o_AttachmentViewer_headerItemButtonIcon fa fa-download fa-fw" t-att-class="{ 'o-hasLabel me-2': messaging.device.sizeClass > messaging.device.sizeClasses.MD }" role="img"/>
+                        <t t-if="messaging.device.sizeClass > messaging.device.sizeClasses.MD">
                             <span>Download</span>
                         </t>
                     </div>
diff --git a/addons/mail/static/src/components/dialog_manager/dialog_manager.js b/addons/mail/static/src/components/dialog_manager/dialog_manager.js
index f821053eae6..0f8d4d36ca2 100644
--- a/addons/mail/static/src/components/dialog_manager/dialog_manager.js
+++ b/addons/mail/static/src/components/dialog_manager/dialog_manager.js
@@ -39,16 +39,12 @@ export class DialogManager extends Component {
      * @private
      */
     _checkDialogOpen() {
-        if (!this.messaging || !this.messaging.dialogManager) {
-            return;
-        }
-        if (this.messaging.dialogManager.dialogs.length > 0) {
+        if (this.dialogManager.dialogs.length > 0) {
             document.body.classList.add('modal-open');
         } else {
             document.body.classList.remove('modal-open');
         }
     }
-
 }
 
 Object.assign(DialogManager, {
diff --git a/addons/mail/static/src/components/dialog_manager_container/dialog_manager_container.js b/addons/mail/static/src/components/dialog_manager_container/dialog_manager_container.js
index 64f1a40bafa..95c30e326f8 100644
--- a/addons/mail/static/src/components/dialog_manager_container/dialog_manager_container.js
+++ b/addons/mail/static/src/components/dialog_manager_container/dialog_manager_container.js
@@ -5,7 +5,7 @@ import { useModels } from '@mail/component_hooks/use_models';
 import '@mail/components/dialog_manager/dialog_manager';
 import { getMessagingComponent } from "@mail/utils/messaging_component";
 
-const { Component, useSubEnv } = owl;
+const { Component } = owl;
 
 export class DialogManagerContainer extends Component {
 
@@ -13,9 +13,6 @@ export class DialogManagerContainer extends Component {
      * @override
      */
     setup() {
-        // for now, the legacy env is needed for internal functions such as
-        // `useModels` to work
-        useSubEnv(Component.env);
         useModels();
         super.setup();
     }
diff --git a/addons/mail/static/src/components/discuss_container/discuss_container.js b/addons/mail/static/src/components/discuss_container/discuss_container.js
index 936de438be2..f2dd2503384 100644
--- a/addons/mail/static/src/components/discuss_container/discuss_container.js
+++ b/addons/mail/static/src/components/discuss_container/discuss_container.js
@@ -14,9 +14,6 @@ export class DiscussContainer extends Component {
      * @override
      */
     setup() {
-        // for now, the legacy env is needed for internal functions such as
-        // `useModels` to work
-        this.env = Component.env;
         useModels();
         super.setup();
         onWillDestroy(() => this._willDestroy());
@@ -30,7 +27,6 @@ export class DiscussContainer extends Component {
             this.discuss.update({
                 discussView: insertAndReplace({
                     actionId: action.id,
-                    actionManager: this.props.actionManager,
                 }),
                 initActiveId,
             });
@@ -48,7 +44,7 @@ export class DiscussContainer extends Component {
          * When executing the discuss action while it's already opened, the
          * action manager first mounts the newest DiscussContainer, then
          * unmounts the oldest one. The issue is that messaging.discussView is
-         * updated on setup but is cleared during the unmount. This leads to
+         * updated on setup but is cleared on destroy. This leads to
          * errors because there is no discussView anymore. In order to handle
          * this situation, let's keep a reference to the currentInstance so that
          * we can check we're deleting the discussView only when there is no
@@ -68,7 +64,9 @@ export class DiscussContainer extends Component {
 Object.assign(DiscussContainer, {
     props: {
         action: Object,
-        actionManager: Object,
+        actionId: { type: Number, optional: 1 },
+        className: String,
+        globalState: { type: Object, optional: 1 },
     },
     components: { Discuss: getMessagingComponent('Discuss') },
     template: 'mail.DiscussContainer',
diff --git a/addons/mail/static/src/components/discuss_container/discuss_container.xml b/addons/mail/static/src/components/discuss_container/discuss_container.xml
index c5c14450413..967d263ee3c 100644
--- a/addons/mail/static/src/components/discuss_container/discuss_container.xml
+++ b/addons/mail/static/src/components/discuss_container/discuss_container.xml
@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
 
     <t t-name="mail.DiscussContainer" owl="1">
-        <div class="o_DiscussContainer d-flex flex-grow-1 flex-column">
+        <div class="o_DiscussContainer h-100 d-flex flex-grow-1 flex-column">
             <Discuss t-if="messaging and messaging.discuss and messaging.discuss.discussView and messaging.isInitialized" className="'flex-grow-1'" record="messaging.discuss.discussView"/>
             <div t-else="" class="o_DiscussContainer_spinner d-flex flex-grow-1 align-items-center justify-content-center">
                 <i class="o_DiscussContainer_spinnerIcon fa fa-circle-o-notch fa-spin me-2"/>Please wait...
diff --git a/addons/mail/static/src/components/discuss_public_view/discuss_public_view.xml b/addons/mail/static/src/components/discuss_public_view/discuss_public_view.xml
index 3d1fb1aeb23..f42bf52dafe 100644
--- a/addons/mail/static/src/components/discuss_public_view/discuss_public_view.xml
+++ b/addons/mail/static/src/components/discuss_public_view/discuss_public_view.xml
@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
     <t t-name="mail.DiscussPublicView" owl="1">
         <t t-if="discussPublicView">
-            <div class="o_DiscussPublicView d-flex flex-column h-100" t-attf-class="{{ className }}" t-ref="root">
+            <div class="o_DiscussPublicView d-flex flex-column h-100 w-100 position-absolute" t-attf-class="{{ className }}" t-ref="root">
                 <ThreadView t-if="discussPublicView.threadView"
                     record="discussPublicView.threadView"
                 />
diff --git a/addons/mail/static/src/components/discuss_public_view_container/discuss_public_view_container.js b/addons/mail/static/src/components/discuss_public_view_container/discuss_public_view_container.js
index 9373574c03f..3c232df6b3f 100644
--- a/addons/mail/static/src/components/discuss_public_view_container/discuss_public_view_container.js
+++ b/addons/mail/static/src/components/discuss_public_view_container/discuss_public_view_container.js
@@ -5,7 +5,7 @@ import { useModels } from '@mail/component_hooks/use_models';
 import '@mail/components/discuss_public_view/discuss_public_view';
 import { getMessagingComponent } from "@mail/utils/messaging_component";
 
-const { Component, useSubEnv } = owl;
+const { Component } = owl;
 
 export class DiscussPublicViewContainer extends Component {
 
@@ -13,9 +13,6 @@ export class DiscussPublicViewContainer extends Component {
      * @override
      */
     setup() {
-        // for now, the legacy env is needed for internal functions such as
-        // `useModels` to work
-        useSubEnv(Component.env);
         useModels();
         super.setup();
     }
diff --git a/addons/mail/static/src/components/messaging_menu_container/messaging_menu_container.js b/addons/mail/static/src/components/messaging_menu_container/messaging_menu_container.js
index 98f80fe47e8..efa9ab2064d 100644
--- a/addons/mail/static/src/components/messaging_menu_container/messaging_menu_container.js
+++ b/addons/mail/static/src/components/messaging_menu_container/messaging_menu_container.js
@@ -5,7 +5,7 @@ import { useModels } from '@mail/component_hooks/use_models';
 import '@mail/components/messaging_menu/messaging_menu';
 import { getMessagingComponent } from "@mail/utils/messaging_component";
 
-const { Component, useSubEnv } = owl;
+const { Component } = owl;
 
 export class MessagingMenuContainer extends Component {
 
@@ -13,9 +13,6 @@ export class MessagingMenuContainer extends Component {
      * @override
      */
     setup() {
-        // for now, the legacy env is needed for internal functions such as
-        // `useModels` to work
-        useSubEnv(Component.env);
         useModels();
         super.setup();
     }
diff --git a/addons/mail/static/src/components/notification_request/notification_request.js b/addons/mail/static/src/components/notification_request/notification_request.js
index f4ba5154762..1730860a0e1 100644
--- a/addons/mail/static/src/components/notification_request/notification_request.js
+++ b/addons/mail/static/src/components/notification_request/notification_request.js
@@ -31,7 +31,7 @@ export class NotificationRequest extends Component {
     _handleResponseNotificationPermission(value) {
         this.messaging.refreshIsNotificationPermissionDefault();
         if (value !== 'granted') {
-            this.env.services['bus_service'].sendNotification({
+            this.env.services['legacy_bus_service'].sendNotification({
                 message: this.env._t("Odoo will not have the permission to send native notifications on this device."),
                 title: this.env._t("Permission denied"),
             });
diff --git a/addons/mail/static/src/components/rtc_activity_notice_container/rtc_activity_notice_container.js b/addons/mail/static/src/components/rtc_activity_notice_container/rtc_activity_notice_container.js
index c0ed9eda5da..facc5e6de85 100644
--- a/addons/mail/static/src/components/rtc_activity_notice_container/rtc_activity_notice_container.js
+++ b/addons/mail/static/src/components/rtc_activity_notice_container/rtc_activity_notice_container.js
@@ -5,7 +5,7 @@ import { useModels } from '@mail/component_hooks/use_models';
 import '@mail/components/rtc_activity_notice/rtc_activity_notice';
 import { getMessagingComponent } from "@mail/utils/messaging_component";
 
-const { Component, useSubEnv } = owl;
+const { Component } = owl;
 
 export class RtcActivityNoticeContainer extends Component {
 
@@ -13,9 +13,6 @@ export class RtcActivityNoticeContainer extends Component {
      * @override
      */
     setup() {
-        // for now, the legacy env is needed for internal functions such as
-        // `useModels` to work
-        useSubEnv(Component.env);
         useModels();
         super.setup();
     }
diff --git a/addons/mail/static/src/js/tours/mail.js b/addons/mail/static/src/js/tours/mail.js
index ddda18795f7..a70637fef47 100644
--- a/addons/mail/static/src/js/tours/mail.js
+++ b/addons/mail/static/src/js/tours/mail.js
@@ -5,7 +5,7 @@ import { Markup } from 'web.utils';
 import tour from 'web_tour.tour';
 
 tour.register('mail_tour', {
-    url: "/web#action=mail.widgets.discuss",
+    url: "/web#action=mail.action_discuss",
     sequence: 80,
 }, [{
     trigger: '.o_DiscussSidebar_categoryChannel .o_DiscussSidebarCategory_commandAdd',
diff --git a/addons/mail/static/src/main.js b/addons/mail/static/src/main.js
index 04e5c66b4a2..d6dba4a81d6 100644
--- a/addons/mail/static/src/main.js
+++ b/addons/mail/static/src/main.js
@@ -2,17 +2,26 @@
 
 import { ChatWindowManagerContainer } from '@mail/components/chat_window_manager_container/chat_window_manager_container';
 import { DialogManagerContainer } from '@mail/components/dialog_manager_container/dialog_manager_container';
-import { MessagingService } from '@mail/services/messaging/messaging';
-import { SystrayService } from '@mail/services/systray_service/systray_service';
-import { DiscussWidget } from '@mail/widgets/discuss/discuss';
+import { DiscussContainer } from '@mail/components/discuss_container/discuss_container';
+import { messagingService } from '@mail/services/messaging_service';
+import { systrayService } from '@mail/services/systray_service';
+import { makeMessagingToLegacyEnv } from '@mail/utils/make_messaging_to_legacy_env';
 
-import { serviceRegistry, action_registry } from 'web.core';
 import { registry } from '@web/core/registry';
 
-serviceRegistry.add('messaging', MessagingService);
-serviceRegistry.add('systray_service', SystrayService);
+const messagingValuesService = {
+    start() {
+        return {};
+    }
+};
 
-action_registry.add('mail.widgets.discuss', DiscussWidget);
+const serviceRegistry = registry.category('services');
+serviceRegistry.add('messaging', messagingService);
+serviceRegistry.add('messagingValues', messagingValuesService);
+serviceRegistry.add('systray_service', systrayService);
+serviceRegistry.add('messaging_to_legacy_env', makeMessagingToLegacyEnv(owl.Component.env));
+
+registry.category('actions').add('mail.action_discuss', DiscussContainer);
 
 registry.category('main_components').add('DialogManagerContainer', { Component: DialogManagerContainer });
 registry.category('main_components').add('ChatWindowManagerContainer', { Component: ChatWindowManagerContainer });
diff --git a/addons/mail/static/src/model/model_manager.js b/addons/mail/static/src/model/model_manager.js
index 0145856a232..19d90ea1a64 100644
--- a/addons/mail/static/src/model/model_manager.js
+++ b/addons/mail/static/src/model/model_manager.js
@@ -134,11 +134,6 @@ export class ModelManager {
          * "Promise time".
          */
         await new Promise(resolve => setTimeout(resolve));
-        /**
-         * Some models require session data, like locale text direction (depends on
-         * fully loaded translation).
-         */
-        await this.env.session.is_bound;
         this._generateModels();
         /**
          * Create the messaging singleton record.
diff --git a/addons/mail/static/src/models/activity.js b/addons/mail/static/src/models/activity.js
index 2a3fbc77a73..a28723cea9b 100644
--- a/addons/mail/static/src/models/activity.js
+++ b/addons/mail/static/src/models/activity.js
@@ -134,10 +134,10 @@ registerModel({
                 },
                 res_id: this.id,
             };
-            this.env.bus.trigger('do-action', {
+            this.env.services.action.doAction(
                 action,
-                options: { on_close: () => this.fetchAndUpdate() },
-            });
+                { onClose: () => this.fetchAndUpdate() },
+            );
         },
         async fetchAndUpdate() {
             const [data] = await this.messaging.rpc({
@@ -210,17 +210,17 @@ registerModel({
             if (!action) {
                 return;
             }
-            this.env.bus.trigger('do-action', {
+            this.env.services.action.doAction(
                 action,
-                options: {
-                    on_close: () => {
+                {
+                    onClose: () => {
                         if (!thread.exists()) {
                             return;
                         }
                         thread.fetchData(['activities']);
                     },
                 },
-            });
+            );
         },
         /**
          * @private
diff --git a/addons/mail/static/src/models/chatter.js b/addons/mail/static/src/models/chatter.js
index 2a7c56d0f1f..84529f8ad2a 100644
--- a/addons/mail/static/src/models/chatter.js
+++ b/addons/mail/static/src/models/chatter.js
@@ -82,12 +82,12 @@ registerModel({
                 },
                 res_id: false,
             };
-            return this.env.bus.trigger('do-action', {
+            return this.env.services.action.doAction(
                 action,
-                options: {
-                    on_close: () => this.reloadParentView(),
-                },
-            });
+                {
+                    onClose: () => this.reloadParentView(),
+                }
+            );
         },
         /**
          * Handles click on "send message" button.
diff --git a/addons/mail/static/src/models/composer_view.js b/addons/mail/static/src/models/composer_view.js
index 3657b221150..6d7897aa422 100644
--- a/addons/mail/static/src/models/composer_view.js
+++ b/addons/mail/static/src/models/composer_view.js
@@ -533,7 +533,7 @@ registerModel({
             };
             const composer = this.composer;
             const options = {
-                on_close: () => {
+                onClose: () => {
                     if (!composer.exists()) {
                         return;
                     }
@@ -543,7 +543,7 @@ registerModel({
                     }
                 },
             };
-            await this.env.bus.trigger('do-action', { action, options });
+            await this.env.services.action.doAction(action, options);
         },
         /**
          * Post a message in provided composer's thread based on current composer fields values.
diff --git a/addons/mail/static/src/models/device.js b/addons/mail/static/src/models/device.js
index 921a424f2d7..d6b20684098 100644
--- a/addons/mail/static/src/models/device.js
+++ b/addons/mail/static/src/models/device.js
@@ -3,6 +3,8 @@
 import { registerModel } from '@mail/model/model_core';
 import { attr } from '@mail/model/model_field';
 import { browser } from "@web/core/browser/browser";
+import { isMobileOS } from "@web/core/browser/feature_detection";
+import { SIZES } from '@web/core/ui/ui_service';
 
 registerModel({
     name: 'Device',
@@ -30,9 +32,9 @@ registerModel({
             this.update({
                 globalWindowInnerHeight: this.messaging.browser.innerHeight,
                 globalWindowInnerWidth: this.messaging.browser.innerWidth,
-                isMobileDevice: this.env.device.isMobileDevice,
-                isSmall: this.env.device.isMobile,
-                sizeClass: this.env.device.size_class,
+                isMobileDevice: isMobileOS(),
+                isSmall: this.env.isSmall,
+                sizeClass: this.env.services.ui.size,
             });
         },
     },
@@ -56,5 +58,8 @@ registerModel({
          * attribute.
          */
         sizeClass: attr(),
+        sizeClasses: attr({
+            default: SIZES,
+        }),
     },
 });
diff --git a/addons/mail/static/src/models/discuss.js b/addons/mail/static/src/models/discuss.js
index 4bec19bc910..bdb5620861a 100644
--- a/addons/mail/static/src/models/discuss.js
+++ b/addons/mail/static/src/models/discuss.js
@@ -162,14 +162,14 @@ registerModel({
                 this.focus();
             }
             if (!this.discussView) {
-                this.env.bus.trigger('do-action', {
-                    action: 'mail.action_discuss',
-                    options: {
+                this.env.services.action.doAction(
+                    'mail.action_discuss',
+                    {
                         active_id: this.threadToActiveId(this),
                         clear_breadcrumbs: false,
                         on_reverse_breadcrumb: () => this.close(), // this is useless, close is called by destroy anyway
                     },
-                });
+                );
             }
         },
         /**
diff --git a/addons/mail/static/src/models/discuss_sidebar_category.js b/addons/mail/static/src/models/discuss_sidebar_category.js
index 65d6df20a6c..55b1c624795 100644
--- a/addons/mail/static/src/models/discuss_sidebar_category.js
+++ b/addons/mail/static/src/models/discuss_sidebar_category.js
@@ -176,14 +176,12 @@ registerModel({
          */
         onClickCommandView(ev) {
             ev.stopPropagation();
-            return this.env.bus.trigger('do-action', {
-                action: {
-                    name: this.env._t("Public Channels"),
-                    type: 'ir.actions.act_window',
-                    res_model: 'mail.channel',
-                    views: [[false, 'kanban'], [false, 'form']],
-                    domain: [['public', '!=', 'private']],
-                },
+            return this.env.services.action.doAction({
+                name: this.env._t("Public Channels"),
+                type: 'ir.actions.act_window',
+                res_model: 'mail.channel',
+                views: [[false, 'kanban'], [false, 'form']],
+                domain: [['public', '!=', 'private']],
             });
         },
         /**
diff --git a/addons/mail/static/src/models/discuss_sidebar_category_item.js b/addons/mail/static/src/models/discuss_sidebar_category_item.js
index 4ca911b23d5..6bbd0c3c0e2 100644
--- a/addons/mail/static/src/models/discuss_sidebar_category_item.js
+++ b/addons/mail/static/src/models/discuss_sidebar_category_item.js
@@ -134,14 +134,12 @@ registerModel({
          */
         onClickCommandSettings(ev) {
             ev.stopPropagation();
-            return this.env.bus.trigger('do-action', {
-                action: {
-                    type: 'ir.actions.act_window',
-                    res_model: this.channel.model,
-                    res_id: this.channel.id,
-                    views: [[false, 'form']],
-                    target: 'current',
-                },
+            return this.env.services.action.doAction({
+                type: 'ir.actions.act_window',
+                res_model: this.channel.model,
+                res_id: this.channel.id,
+                views: [[false, 'form']],
+                target: 'current',
             });
         },
         /**
diff --git a/addons/mail/static/src/models/discuss_view.js b/addons/mail/static/src/models/discuss_view.js
index 7d91175a0f2..5ff4b97a61e 100644
--- a/addons/mail/static/src/models/discuss_view.js
+++ b/addons/mail/static/src/models/discuss_view.js
@@ -45,9 +45,9 @@ registerModel({
          * Handles OWL update on the discuss component.
          */
         onComponentUpdate() {
-            if (this.discuss.thread && this.actionManager) {
+            if (this.discuss.thread) {
                 if (this.lastPushStateActiveThread !== this.discuss.thread) {
-                    this.actionManager.do_push_state({
+                    this.env.services.router.pushState({
                         action: this.actionId,
                         active_id: this.discuss.activeId,
                     });
@@ -63,7 +63,7 @@ registerModel({
                 this.lastThreadCache && this.lastThreadCache.localId === this.discuss.threadView.threadCache.localId &&
                 this.lastThreadCounter > 0 && this.discuss.thread.counter === 0
             ) {
-                this.env.bus.trigger('show-effect', {
+                this.env.services.effect.add({
                     message: this.env._t("Congratulations, your inbox is empty!"),
                     type: 'rainbow_man',
                 });
@@ -156,11 +156,6 @@ registerModel({
          * The id of the action which opened discuss.
          */
         actionId: attr(),
-        /**
-         * Used to push state when changing active thread.
-         * The actionManager passed to the discuss widget.
-         */
-        actionManager: attr(),
         discuss: one('Discuss', {
             inverse: 'discussView',
             readonly: true,
diff --git a/addons/mail/static/src/models/locale.js b/addons/mail/static/src/models/locale.js
index 7e8f39466af..98cc402a36f 100644
--- a/addons/mail/static/src/models/locale.js
+++ b/addons/mail/static/src/models/locale.js
@@ -3,6 +3,8 @@
 import { registerModel } from '@mail/model/model_core';
 import { attr } from '@mail/model/model_field';
 
+import { localization } from '@web/core/l10n/localization';
+
 registerModel({
     name: 'Locale',
     identifyingFields: ['messaging'],
@@ -12,14 +14,14 @@ registerModel({
          * @returns {string}
          */
         _computeLanguage() {
-            return this.env._t.database.parameters.code;
+            return this.env.services.user.lang;
         },
         /**
          * @private
          * @returns {string}
          */
         _computeTextDirection() {
-            return this.env._t.database.parameters.direction;
+            return localization.direction;
         },
     },
     fields: {
diff --git a/addons/mail/static/src/models/mail_template.js b/addons/mail/static/src/models/mail_template.js
index a44d6936126..0c28e1d0d4e 100644
--- a/addons/mail/static/src/models/mail_template.js
+++ b/addons/mail/static/src/models/mail_template.js
@@ -25,14 +25,10 @@ registerModel({
                     force_email: true,
                 },
             };
-            this.env.bus.trigger('do-action', {
+            this.env.services.action.doAction(
                 action,
-                options: {
-                    on_close: () => {
-                        activity.thread.fetchData(['attachments', 'messages']);
-                    },
-                },
-            });
+                { onClose: () => activity.thread.fetchData(['attachments', 'messages']) }
+            );
         },
         /**
          * @param {Activity} activity
diff --git a/addons/mail/static/src/models/message.js b/addons/mail/static/src/models/message.js
index 9fc77200fdb..fab793a800f 100644
--- a/addons/mail/static/src/models/message.js
+++ b/addons/mail/static/src/models/message.js
@@ -231,14 +231,14 @@ registerModel({
          * Opens the view that allows to resend the message in case of failure.
          */
         openResendAction() {
-            this.env.bus.trigger('do-action', {
-                action: 'mail.mail_resend_message_action',
-                options: {
+            this.env.services.action.doAction(
+                'mail.mail_resend_message_action',
+                {
                     additional_context: {
                         mail_message_to_resend: this.id,
                     },
-                },
-            });
+                }
+            );
         },
         /**
          * Removes the given reaction from this message.
diff --git a/addons/mail/static/src/models/messaging.js b/addons/mail/static/src/models/messaging.js
index 250409d6b65..7d906ec08b2 100644
--- a/addons/mail/static/src/models/messaging.js
+++ b/addons/mail/static/src/models/messaging.js
@@ -15,8 +15,8 @@ registerModel({
     identifyingFields: [],
     lifecycleHooks: {
         _willDelete() {
-            if (this.env.services['bus_service']) {
-                this.env.services['bus_service'].off('window_focus', null, this._handleGlobalWindowFocus);
+            if (this.env.services['legacy_bus_service']) {
+                this.env.services['legacy_bus_service'].off('window_focus', null, this._handleGlobalWindowFocus);
             }
         },
     },
@@ -25,7 +25,7 @@ registerModel({
          * Starts messaging and related records.
          */
         async start() {
-            this.env.services['bus_service'].on('window_focus', null, this._handleGlobalWindowFocus);
+            this.env.services['legacy_bus_service'].on('window_focus', null, this._handleGlobalWindowFocus);
             await this.initializer.start();
             if (!this.exists()) {
                 return;
@@ -70,7 +70,8 @@ registerModel({
          * @return {number} the id of the notification.
          */
         notify(params) {
-            return this.env.services.notification.notify(params);
+            const { message, ...options } = params;
+            return this.env.services.notification.add(message, options);
         },
         /**
          * Opens a chat with the provided person and returns it.
@@ -100,13 +101,11 @@ registerModel({
          * @param {string} param0.model
          */
         async openDocument({ id, model }) {
-            this.env.bus.trigger('do-action', {
-                action: {
-                    type: 'ir.actions.act_window',
-                    res_model: model,
-                    views: [[false, 'form']],
-                    res_id: id,
-                },
+            this.env.services.action.doAction({
+                type: 'ir.actions.act_window',
+                res_model: model,
+                views: [[false, 'form']],
+                res_id: id,
             });
             if (this.messaging.device.isSmall) {
                 // messaging menu has a higher z-index than views so it must
@@ -157,8 +156,35 @@ registerModel({
          * @param {Object} params
          * @return {any}
          */
-        async rpc(params, options) {
-            return this.env.services.rpc(params, options);
+        async rpc(params, options = {}) {
+            if (params.route) {
+                const { route, params: rpcParameters } = params;
+                const { shadow: silent, ...rpcSettings } = options;
+                return this.env.services.rpc(route, rpcParameters, { silent, ...rpcSettings });
+            } else {
+                const { args, method, model, kwargs = {} } = params;
+                const { context, domain, fields, groupBy, ...ormOptions } = kwargs;
+
+                const ormService = 'shadow' in options ? this.env.services.orm.silent : this.env.services.orm;
+                switch (method) {
+                    case 'create':
+                        return ormService.create(model, args[0], context);
+                    case 'read':
+                        return ormService.read(model, args[0], args.length > 1 ? args[1] : undefined, context);
+                    case 'read_group':
+                        return ormService.readGroup(model, domain, fields, groupBy, ormOptions, context);
+                    case 'search':
+                        return ormService.search(model, args[0], ormOptions, context);
+                    case 'search_read':
+                        return ormService.searchRead(model, domain, fields, ormOptions, context);
+                    case 'unlink':
+                        return ormService.unlink(model, args[0], context);
+                    case 'write':
+                        return ormService.write(model, args[0], args[1], context);
+                    default:
+                        return ormService.call(model, method, args, kwargs);
+                }
+            }
         },
         /**
          * Refreshes the value of `isNotificationPermissionDefault`.
diff --git a/addons/mail/static/src/models/messaging_notification_handler.js b/addons/mail/static/src/models/messaging_notification_handler.js
index ad8cceaf9f3..c850e8919e7 100644
--- a/addons/mail/static/src/models/messaging_notification_handler.js
+++ b/addons/mail/static/src/models/messaging_notification_handler.js
@@ -16,9 +16,9 @@ registerModel({
     identifyingFields: ['messaging'],
     lifecycleHooks: {
         _willDelete() {
-            if (this.env.services['bus_service']) {
-                this.env.services['bus_service'].off('notification');
-                this.env.services['bus_service'].stopPolling();
+            if (this.env.services['legacy_bus_service']) {
+                this.env.services['legacy_bus_service'].off('notification');
+                this.env.services['legacy_bus_service'].stopPolling();
             }
         },
     },
@@ -28,8 +28,8 @@ registerModel({
          * the current users. This includes pinned channels for instance.
          */
         start() {
-            this.env.services.bus_service.onNotification(null, notifs => this._handleNotifications(notifs));
-            this.env.services.bus_service.startPolling();
+            this.env.services.legacy_bus_service.onNotification(null, notifs => this._handleNotifications(notifs));
+            this.env.services.legacy_bus_service.startPolling();
         },
         /**
          * @private
@@ -269,7 +269,7 @@ registerModel({
                 channel.correspondent === this.messaging.partnerRoot
             );
             if (!isChatWithOdooBot) {
-                const isOdooFocused = this.env.services['bus_service'].isOdooFocused();
+                const isOdooFocused = this.env.services['legacy_bus_service'].isOdooFocused();
                 // Notify if out of focus
                 if (!isOdooFocused && channel.isChatChannel) {
                     this._notifyNewChannelMessageWhileOutOfFocus({
@@ -657,7 +657,7 @@ registerModel({
             // then open a chat for the current user with the new user.
             const message = sprintf(this.env._t('%s connected'), username);
             const title = this.env._t("This is their first connection. Wish them luck.");
-            this.env.services['bus_service'].sendNotification({ message, title, type: 'info' });
+            this.env.services['legacy_bus_service'].sendNotification({ message, title, type: 'info' });
             const chat = await this.messaging.getChat({ partnerId });
             if (!this.exists() || !chat || this.messaging.device.isSmall) {
                 return;
@@ -699,7 +699,7 @@ registerModel({
             const notificationContent = escape(
                 htmlToTextContentInline(message.body).substr(0, PREVIEW_MSG_MAX_SIZE)
             );
-            this.env.services['bus_service'].sendNotification({
+            this.env.services['legacy_bus_service'].sendNotification({
                 message: notificationContent,
                 title: notificationTitle,
                 type: 'info',
diff --git a/addons/mail/static/src/models/notification_group.js b/addons/mail/static/src/models/notification_group.js
index 2f710566f14..fd8f2600927 100644
--- a/addons/mail/static/src/models/notification_group.js
+++ b/addons/mail/static/src/models/notification_group.js
@@ -88,17 +88,15 @@ registerModel({
             if (this.notification_type !== 'email') {
                 return;
             }
-            this.env.bus.trigger('do-action', {
-                action: {
-                    name: this.env._t("Mail Failures"),
-                    type: 'ir.actions.act_window',
-                    view_mode: 'kanban,list,form',
-                    views: [[false, 'kanban'], [false, 'list'], [false, 'form']],
-                    target: 'current',
-                    res_model: this.res_model,
-                    domain: [['message_has_error', '=', true]],
-                    context: { create: false },
-                },
+            this.env.services.action.doAction({
+                name: this.env._t("Mail Failures"),
+                type: 'ir.actions.act_window',
+                view_mode: 'kanban,list,form',
+                views: [[false, 'kanban'], [false, 'list'], [false, 'form']],
+                target: 'current',
+                res_model: this.res_model,
+                domain: [['message_has_error', '=', true]],
+                context: { create: false },
             });
             if (this.messaging.device.isSmall) {
                 // messaging menu has a higher z-index than views so it must
diff --git a/addons/mail/static/src/models/rtc_call_participant_card.js b/addons/mail/static/src/models/rtc_call_participant_card.js
index 9989c96d8f6..d7069e9e386 100644
--- a/addons/mail/static/src/models/rtc_call_participant_card.js
+++ b/addons/mail/static/src/models/rtc_call_participant_card.js
@@ -88,7 +88,7 @@ registerModel({
          * @returns {boolean}
          */
         _computeHasConnectionInfo() {
-            return Boolean(this.rtcSession && this.env.isDebug() && this.channel.rtc);
+            return Boolean(this.rtcSession && this.env.debug && this.channel.rtc);
         },
         /**
          * @private
diff --git a/addons/mail/static/src/models/thread.js b/addons/mail/static/src/models/thread.js
index 8b0c6c483af..5d8fcbdb7f2 100644
--- a/addons/mail/static/src/models/thread.js
+++ b/addons/mail/static/src/models/thread.js
@@ -1716,18 +1716,18 @@ registerModel({
                     default_res_id: this.id,
                 },
             };
-            this.env.bus.trigger('do-action', {
+            this.env.services.action.doAction(
                 action,
-                options: {
-                    on_close: async () => {
+                {
+                    onClose: async () => {
                         if (!this.exists()) {
                             return;
-                        } 
+                        }
                         await this.fetchData(['followers']);
                         this.env.bus.trigger('Thread:promptAddFollower-closed');
                     },
-                },
-            });
+                }
+            );
         },
         /**
          * @private
diff --git a/addons/mail/static/src/models/tracking_value_item.js b/addons/mail/static/src/models/tracking_value_item.js
index a8e164d5173..28fe783ee35 100644
--- a/addons/mail/static/src/models/tracking_value_item.js
+++ b/addons/mail/static/src/models/tracking_value_item.js
@@ -4,6 +4,7 @@ import { registerModel } from '@mail/model/model_core';
 import { attr, one } from '@mail/model/model_field';
 
 import { format } from 'web.field_utils';
+import { session } from '@web/session';
 
 registerModel({
     name: 'TrackingValueItem',
@@ -53,7 +54,7 @@ registerModel({
                 case 'monetary':
                     return format.monetary(this.value, undefined, {
                         currency: this.currencyId
-                            ? this.env.session.currencies[this.currencyId]
+                            ? session.currencies[this.currencyId]
                             : undefined,
                         forceString: true,
                     });
diff --git a/addons/mail/static/src/public/discuss_public_boot.js b/addons/mail/static/src/public/discuss_public_boot.js
index 88c3fa69614..2bbf404ce74 100644
--- a/addons/mail/static/src/public/discuss_public_boot.js
+++ b/addons/mail/static/src/public/discuss_public_boot.js
@@ -1,20 +1,16 @@
 /** @odoo-module **/
 
 import { data } from 'mail.discuss_public_channel_template';
+import { makeMessagingToLegacyEnv } from '@mail/utils/make_messaging_to_legacy_env';
 
 import { DialogManagerContainer } from '@mail/components/dialog_manager_container/dialog_manager_container';
 import { DiscussPublicViewContainer } from '@mail/components/discuss_public_view_container/discuss_public_view_container';
-import { MessagingService } from '@mail/services/messaging/messaging';
+import { messagingService } from '@mail/services/messaging_service';
 
 import { processTemplates } from '@web/core/assets';
 import { MainComponentsContainer } from '@web/core/main_components_container';
 import { registry } from '@web/core/registry';
 import { makeEnv, startServices } from '@web/env';
-import { session } from '@web/session';
-
-import * as AbstractService from 'web.AbstractService';
-import { serviceRegistry as legacyServiceRegistry } from 'web.core';
-import * as legacyEnv from 'web.env';
 import {
     makeLegacyCrashManagerService,
     makeLegacyDialogMappingService,
@@ -23,6 +19,10 @@ import {
     makeLegacySessionService,
     mapLegacyEnvToWowlEnv,
 } from '@web/legacy/utils';
+import { session } from '@web/session';
+
+import * as AbstractService from 'web.AbstractService';
+import * as legacyEnv from 'web.env';
 import * as legacySession from 'web.session';
 
 const { Component, mount, whenReady } = owl;
@@ -31,6 +31,15 @@ Component.env = legacyEnv;
 
 (async function boot() {
     await whenReady();
+
+    const messagingValuesService = {
+        start() {
+            return {
+                autofetchPartnerImStatus: false,
+            };
+        }
+    };
+
     AbstractService.prototype.deployServices(Component.env);
     const serviceRegistry = registry.category('services');
     serviceRegistry.add('legacy_rpc', makeLegacyRpcService(Component.env));
@@ -38,6 +47,10 @@ Component.env = legacyEnv;
     serviceRegistry.add('legacy_notification', makeLegacyNotificationService(Component.env));
     serviceRegistry.add('legacy_crash_manager', makeLegacyCrashManagerService(Component.env));
     serviceRegistry.add('legacy_dialog_mapping', makeLegacyDialogMappingService(Component.env));
+    serviceRegistry.add('messaging_service_to_legacy_env', makeMessagingToLegacyEnv(Component.env));
+
+    serviceRegistry.add('messaging', messagingService);
+    serviceRegistry.add('messagingValues', messagingValuesService);
 
     const mainComponentsRegistry = registry.category('main_components');
     mainComponentsRegistry.add('DiscussPublicViewContainer', { Component: DiscussPublicViewContainer });
@@ -61,11 +74,6 @@ Component.env = legacyEnv;
     ]);
     mapLegacyEnvToWowlEnv(Component.env, env);
     odoo.isReady = true;
-    legacyServiceRegistry.add('messaging', MessagingService.extend({
-        messagingValues: {
-            autofetchPartnerImStatus: false,
-        },
-    }));
     await mount(MainComponentsContainer, document.body, { env, templates, dev: env.debug });
     createDiscussPublicView();
 })();
diff --git a/addons/mail/static/src/services/messaging/messaging.js b/addons/mail/static/src/services/messaging/messaging.js
deleted file mode 100644
index 31d6f8fb0f6..00000000000
--- a/addons/mail/static/src/services/messaging/messaging.js
+++ /dev/null
@@ -1,34 +0,0 @@
-/** @odoo-module **/
-
-import { ModelManager } from '@mail/model/model_manager';
-
-import AbstractService from 'web.AbstractService';
-
-export const MessagingService = AbstractService.extend({
-    dependencies: ['bus_service'],
-    messagingValues: {},
-    /**
-     * @override
-     */
-    init(env) {
-        this._super(env);
-        this.modelManager = new ModelManager(env);
-    },
-    /**
-     * @override
-     */
-    start() {
-        this._super();
-        this.modelManager.start(this.messagingValues);
-    },
-    /**
-     * Returns the messaging record once it is initialized. This method should
-     * be considered the main entry point to the messaging system for outside
-     * code.
-     *
-     * @returns {Messaging}
-     **/
-    async get() {
-        return this.modelManager.getMessaging();
-    }
-});
diff --git a/addons/mail/static/src/services/messaging_service.js b/addons/mail/static/src/services/messaging_service.js
new file mode 100644
index 00000000000..499d7a3906b
--- /dev/null
+++ b/addons/mail/static/src/services/messaging_service.js
@@ -0,0 +1,44 @@
+/** @odoo-module **/
+
+import { ModelManager } from '@mail/model/model_manager';
+
+export const messagingService = {
+    dependencies: [
+        'effect',
+        'legacy_bus_service',
+        'localization',
+        'messagingValues',
+        'orm',
+        'router',
+        'rpc',
+        'ui',
+        'user',
+    ],
+
+    start(env, { messagingValues }) {
+        const modelManager = new ModelManager(env);
+        this._startModelManager(modelManager, messagingValues);
+
+        return {
+            /**
+             * Returns the messaging record once it is initialized. This method
+             * should be considered the main entry point to the messaging system
+             * for outside code.
+             *
+             * @returns {mail.messaging}
+             **/
+            async get() {
+                return modelManager.getMessaging();
+            },
+            modelManager,
+        };
+    },
+    /**
+     * Separate method to control creation delay in tests.
+     *
+     * @private
+     */
+    _startModelManager(modelManager, messagingValues) {
+        modelManager.start(messagingValues);
+    },
+};
diff --git a/addons/mail/static/src/services/systray_service/systray_service.js b/addons/mail/static/src/services/systray_service.js
similarity index 77%
rename from addons/mail/static/src/services/systray_service/systray_service.js
rename to addons/mail/static/src/services/systray_service.js
index 41e25e7cf83..9553c9cba09 100644
--- a/addons/mail/static/src/services/systray_service/systray_service.js
+++ b/addons/mail/static/src/services/systray_service.js
@@ -3,18 +3,14 @@
 import { MessagingMenuContainer } from '@mail/components/messaging_menu_container/messaging_menu_container';
 import { RtcActivityNoticeContainer } from '@mail/components/rtc_activity_notice_container/rtc_activity_notice_container';
 
-import AbstractService from 'web.AbstractService';
 import { registry } from '@web/core/registry';
 
 const systrayRegistry = registry.category('systray');
 
-export const SystrayService = AbstractService.extend({
+export const systrayService = {
     dependencies: ['messaging'],
-    /**
-     * @override {web.AbstractService}
-     */
-    async start() {
+    start() {
         systrayRegistry.add('mail.MessagingMenuContainer', { Component: MessagingMenuContainer });
         systrayRegistry.add('mail.RtcActivityNoticeContainer', { Component: RtcActivityNoticeContainer }, { sequence: 100 });
     },
-});
+};
diff --git a/addons/mail/static/src/utils/make_messaging_to_legacy_env.js b/addons/mail/static/src/utils/make_messaging_to_legacy_env.js
new file mode 100644
index 00000000000..a9a32563dd3
--- /dev/null
+++ b/addons/mail/static/src/utils/make_messaging_to_legacy_env.js
@@ -0,0 +1,11 @@
+
+/** @odoo-module **/
+
+export function makeMessagingToLegacyEnv(legacyEnv) {
+    return {
+        dependencies: ['messaging'],
+        start(_, { messaging }) {
+            legacyEnv.services.messaging = messaging;
+        },
+    };
+}
diff --git a/addons/mail/static/src/webclient/commands/mail_providers.js b/addons/mail/static/src/webclient/commands/mail_providers.js
index 4cd0ab17f26..81664f16e94 100644
--- a/addons/mail/static/src/webclient/commands/mail_providers.js
+++ b/addons/mail/static/src/webclient/commands/mail_providers.js
@@ -31,7 +31,7 @@ const commandProviderRegistry = registry.category("command_provider");
 commandProviderRegistry.add("partner", {
     namespace: "@",
     async provide(newEnv, options) {
-        const messaging = await Component.env.services.messaging.get();
+        const messaging = await newEnv.services.messaging.get();
         const suggestions = [];
         await messaging.models['Partner'].imSearch({
             callback(partners) {
@@ -58,7 +58,7 @@ commandProviderRegistry.add("partner", {
 commandProviderRegistry.add("channel", {
     namespace: "#",
     async provide(newEnv, options) {
-        const messaging = await Component.env.services.messaging.get();
+        const messaging = await newEnv.services.messaging.get();
         const channels = await messaging.models['Thread'].searchChannelsToOpen({
             limit: 10,
             searchTerm: options.searchValue,
diff --git a/addons/mail/static/src/widgets/discuss/discuss.js b/addons/mail/static/src/widgets/discuss/discuss.js
deleted file mode 100644
index 3da180743bb..00000000000
--- a/addons/mail/static/src/widgets/discuss/discuss.js
+++ /dev/null
@@ -1,74 +0,0 @@
-/** @odoo-module **/
-
-import { DiscussContainer } from "@mail/components/discuss_container/discuss_container";
-
-import AbstractAction from 'web.AbstractAction';
-
-const { App } = owl;
-
-export const DiscussWidget = AbstractAction.extend({
-    template: 'mail.widgets.Discuss',
-    /**
-     * @override {web.AbstractAction}
-     * @param {web.ActionManager} parent
-     * @param {Object} action
-     * @param {Object} [action.context]
-     * @param {string} [action.context.active_id]
-     * @param {Object} [action.params]
-     * @param {string} [action.params.default_active_id]
-     * @param {Object} [options={}]
-     */
-    init(parent, action, options={}) {
-        this._super(...arguments);
-
-        this.app = undefined;
-        this.action = action;
-        this.actionManager = parent;
-    },
-    /**
-     * @override {web.AbstractAction}
-     */
-    destroy() {
-        if (this.app) {
-            this.app.destroy();
-            this.app = undefined;
-        }
-        if (this.$buttons) {
-            this.$buttons.off().remove();
-        }
-        this._super(...arguments);
-    },
-    /**
-     * @override {web.AbstractAction}
-     */
-    async on_attach_callback() {
-        this._super(...arguments);
-        if (this.app) {
-            // prevent twice call to on_attach_callback (FIXME)
-            return;
-        }
-
-        this.app = new App(DiscussContainer, {
-            templates: window.__OWL_TEMPLATES__,
-            env: owl.Component.env,
-            dev: owl.Component.env.isDebug(),
-            translateFn: owl.Component.env._t,
-            translatableAttributes: ["data-tooltip"],
-            props: {
-                action: this.action,
-                actionManager: this.actionManager,
-            },
-        });
-        await this.app.mount(this.el);
-    },
-    /**
-     * @override {web.AbstractAction}
-     */
-    on_detach_callback() {
-        this._super(...arguments);
-        if (this.app) {
-            this.app.destroy();
-        }
-        this.app = undefined;
-    },
-});
diff --git a/addons/mail/static/src/widgets/discuss/discuss.scss b/addons/mail/static/src/widgets/discuss/discuss.scss
deleted file mode 100644
index e7a19f7ec2c..00000000000
--- a/addons/mail/static/src/widgets/discuss/discuss.scss
+++ /dev/null
@@ -1,10 +0,0 @@
-// ------------------------------------------------------------------
-// Layout
-// ------------------------------------------------------------------
-
-.o_widget_Discuss {
-    display: flex;
-    flex: 0 0 100%;
-    flex-flow: column;
-    height: 100%;
-}
diff --git a/addons/mail/static/src/widgets/discuss/discuss.xml b/addons/mail/static/src/widgets/discuss/discuss.xml
deleted file mode 100644
index 5826f157aff..00000000000
--- a/addons/mail/static/src/widgets/discuss/discuss.xml
+++ /dev/null
@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<templates xml:space="preserve">
-
-    <!--
-        @param {mail/static/src/widgets/discuss/discuss.js} widget
-    -->
-    <t t-name="mail.widgets.Discuss">
-        <div class="o_widget_Discuss"/>
-    </t>
-
-</templates>
diff --git a/addons/mail/static/tests/helpers/mock_server.js b/addons/mail/static/tests/helpers/mock_server.js
index 2df186cc7f6..07f98e63d11 100644
--- a/addons/mail/static/tests/helpers/mock_server.js
+++ b/addons/mail/static/tests/helpers/mock_server.js
@@ -1,57 +1,25 @@
 /** @odoo-module **/
 
-import { getPyEnv, nextAnimationFrame } from '@mail/../tests/helpers/test_utils';
+import { getPyEnv, TEST_USER_IDS } from '@mail/../tests/helpers/test_utils';
+
+import { patch } from "@web/core/utils/patch";
+import { MockServer } from "@web/../tests/helpers/mock_server";
 
-import MockServer from 'web.MockServer';
 import { date_to_str, datetime_to_str } from 'web.time';
 
-MockServer.include({
-    /**
-     * Param 'data' may have keys for the different magic partners/users.
-     *
-     * Note: we must delete these keys, so that this is not
-     * handled as a model definition.
-     *
-     * @override
-     * @param {Object} [data.currentPartnerId]
-     * @param {Object} [data.currentUserId]
-     * @param {Object} [data.partnerRootId]
-     * @param {Object} [data.publicPartnerId]
-     * @param {Object} [data.publicUserId]
-     * @param {Widget} [options.widget] mocked widget (use to call services)
-     */
-    init(data, options) {
-        if (data && data.currentPartnerId) {
-            this.currentPartnerId = data.currentPartnerId;
-            delete data.currentPartnerId;
-        }
-        if (data && data.currentUserId) {
-            this.currentUserId = data.currentUserId;
-            delete data.currentUserId;
-        }
-        if (data && data.partnerRootId) {
-            this.partnerRootId = data.partnerRootId;
-            delete data.partnerRootId;
-        }
-        if (data && data.publicPartnerId) {
-            this.publicPartnerId = data.publicPartnerId;
-            delete data.publicPartnerId;
-        }
-        if (data && data.publicUserId) {
-            this.publicUserId = data.publicUserId;
-            delete data.publicUserId;
-        }
-        this._widget = options.widget;
 
+patch(MockServer.prototype, 'mail', {
+    init({ models }) {
         this._super(...arguments);
+        Object.assign(this, TEST_USER_IDS);
 
-        if (this.currentPartnerId) {
+        if (this.currentPartnerId && models && 'res.partner' in models) {
             this.currentPartner = this.getRecords('res.partner', [['id', '=', this.currentPartnerId]])[0];
         }
         MockServer.currentMockServer = this;
         // creation of the ir.model.fields records, required for tracked fields
-        for (const modelName in data) {
-            const fieldNamesToFields = data[modelName].fields;
+        for (const modelName in models) {
+            const fieldNamesToFields = models[modelName].fields;
             for (const fname in fieldNamesToFields) {
                 if (fieldNamesToFields[fname].tracking) {
                     this.mockCreate('ir.model.fields', { model: modelName, name: fname });
@@ -65,6 +33,32 @@ MockServer.include({
     async setup() {
         this.pyEnv = await getPyEnv();
     },
+    /**
+     * @override
+     */
+    async performRPC(route, args) {
+        if (route === '/mail/attachment/upload') {
+            const ufile = args.body.get('ufile');
+            const is_pending = args.body.get('is_pending') === 'true';
+            const model = is_pending ? 'mail.compose.message' : args.body.get('thread_model');
+            const id = is_pending ? 0 : parseInt(args.body.get('thread_id'));
+            const attachmentId = this.mockCreate('ir.attachment', {
+                // datas,
+                mimetype: ufile.type,
+                name: ufile.name,
+                res_id: id,
+                res_model: model,
+            });
+            const attachment = this.getRecords('ir.attachment', [['id', '=', attachmentId]])[0];
+            return {
+                'filename': attachment.name,
+                'id': attachment.id,
+                'mimetype': attachment.mimetype,
+                'size': attachment.file_size
+            };
+        }
+        return this._super(...arguments);
+    },
 
     //--------------------------------------------------------------------------
     // Private
@@ -73,34 +67,11 @@ MockServer.include({
     /**
      * @override
      */
-    async _performFetch(resource, init) {
-        if (resource === '/mail/attachment/upload') {
-            const ufile = init.body.get('ufile');
-            const is_pending = init.body.get('is_pending') === 'true';
-            const model = is_pending ? 'mail.compose.message' : init.body.get('thread_model');
-            const id = is_pending ? 0 : parseInt(init.body.get('thread_id'));
-            const attachmentId = this.pyEnv['ir.attachment'].create({
-                // datas,
-                mimetype: ufile.type,
-                name: ufile.name,
-                res_id: id,
-                res_model: model,
-            });
-            const attachment = this.getRecords('ir.attachment', [['id', '=', attachmentId]])[0];
-            return new window.Response(JSON.stringify({
-                'filename': attachment.name,
-                'id': attachment.id,
-                'mimetype': attachment.mimetype,
-                'size': attachment.file_size
-            }));
-        }
-        return this._super(...arguments);
-    },
-    /**
-     * @override
-     */
-    async _performRpc(route, args) {
+    async _performRPC(route, args) {
         // routes
+        if (route === '/longpolling/im_status') {
+            return [];
+        }
         if (route === '/mail/message/post') {
             if (args.thread_model === 'mail.channel') {
                 return this._mockMailChannelMessagePost(args.thread_id, args.post_data, args.context);
@@ -327,7 +298,7 @@ MockServer.include({
     /**
      * @override
      */
-    _mockWrite(model) {
+    mockWrite(model) {
         const initialTrackedFieldValuesByRecordId = this._mockMailThread_TrackPrepare(model);
         const mockWriteResult = this._super(...arguments);
         if (initialTrackedFieldValuesByRecordId) {
@@ -652,7 +623,7 @@ MockServer.include({
      */
     _mockMailActivityActionDone(ids) {
         const activities = this.getRecords('mail.activity', [['id', 'in', ids]]);
-        this._mockUnlink('mail.activity', [activities.map(activity => activity.id)]);
+        this.mockUnlink('mail.activity', [activities.map(activity => activity.id)]);
     },
     /**
      * Simulates `action_feedback` on `mail.activity`.
@@ -1249,7 +1220,7 @@ MockServer.include({
             return matchingChannels;
         };
 
-        const mentionSuggestions = mentionSuggestionsFilter(this.data['mail.channel'].records, search, limit);
+        const mentionSuggestions = mentionSuggestionsFilter(this.models['mail.channel'].records, search, limit);
 
         return mentionSuggestions;
     },
@@ -1442,9 +1413,6 @@ MockServer.include({
      * @returns {Object[]}
      */
     async _mockMailMessage_MessageFetch(domain, max_id, min_id, limit = 30) {
-        // TODO FIXME delay RPC until next potential render as a workaround
-        // to OWL issue (possibly https://github.com/odoo/owl/issues/904)
-        await nextAnimationFrame();
         if (max_id) {
             domain.push(['id', '<', max_id]);
         }
@@ -1782,7 +1750,7 @@ MockServer.include({
             if (record.user_id) {
                 const user = this.getRecords('res.users', [['id', '=', record.user_id]]);
                 if (user.partner_id) {
-                    const reason = this.data[model].fields['user_id'].string;
+                    const reason = this.models[model].fields['user_id'].string;
                     this._mockMailThread_MessageAddSuggestedRecipient(result, user.partner_id, reason);
                 }
             }
@@ -1967,9 +1935,9 @@ MockServer.include({
      * Simulates `_message_track` on `mail.thread`
      */
     _mockMailThread_MessageTrack(modelName, trackedFieldNames, initialTrackedFieldValuesByRecordId) {
-        const trackFieldNamesToField = this._mockFieldsGet(modelName, [trackedFieldNames]);
+        const trackFieldNamesToField = this.mockFieldsGet(modelName, [trackedFieldNames]);
         const tracking = {};
-        const records = this.data[modelName].records;
+        const records = this.models[modelName].records;
         for (const record of records) {
             tracking[record.id] = this._mockMailBaseModel_MailTrack(modelName, trackFieldNamesToField, initialTrackedFieldValuesByRecordId[record.id], record);
         }
@@ -2005,7 +1973,7 @@ MockServer.include({
      * Simulates `_track_get_fields` on `mail.thread`
      */
     _mockMailThread_TrackGetFields(model) {
-        return Object.entries(this.data[model].fields).reduce((prev, next) => {
+        return Object.entries(this.models[model].fields).reduce((prev, next) => {
             if (next[1].tracking) {
                 prev.push(next[0]);
             }
@@ -2021,7 +1989,7 @@ MockServer.include({
             return;
         }
         const initialTrackedFieldValuesByRecordId = {};
-        for (const record of this.data[model].records) {
+        for (const record of this.models[model].records) {
             const values = {};
             initialTrackedFieldValuesByRecordId[record.id] = values;
             for (const fname of trackedFieldNames) {
@@ -2041,7 +2009,7 @@ MockServer.include({
      */
      _mockMailTrackingValue_CreateTrackingValues(initialValue, newValue, fieldName, field, modelName) {
         let isTracked = true;
-        const irField = this.data['ir.model.fields'].records.find(field => field.model === modelName && field.name === fieldName);
+        const irField = this.models['ir.model.fields'].records.find(field => field.model === modelName && field.name === fieldName);
 
         if (!irField) {
             return;
@@ -2504,36 +2472,4 @@ MockServer.include({
             ),
         });
     },
-
-    //--------------------------------------------------------------------------
-    // New mock server compatibility
-    //--------------------------------------------------------------------------
-
-    getRecords() {
-        return this._getRecords(...arguments);
-    },
-    mockCreate() {
-        return this._mockCreate(...arguments);
-    },
-    mockRead() {
-        return this._mockRead(...arguments);
-    },
-    mockReadGroup() {
-        return this._mockReadGroup(...arguments);
-    },
-    mockSearch() {
-        return this._mockSearch(...arguments);
-    },
-    mockSearchCount() {
-        return this._mockSearchCount(...arguments);
-    },
-    mockSearchRead() {
-        return this._mockSearchRead(...arguments);
-    },
-    mockUnlink() {
-        return this._mockUnlink(...arguments);
-    },
-    mockWrite() {
-        return this._mockWrite(...arguments);
-    },
 });
diff --git a/addons/mail/static/tests/helpers/test_utils.js b/addons/mail/static/tests/helpers/test_utils.js
index c354fcf3647..a807e615cb6 100644
--- a/addons/mail/static/tests/helpers/test_utils.js
+++ b/addons/mail/static/tests/helpers/test_utils.js
@@ -1,39 +1,22 @@
 /** @odoo-module **/
 
-import BusService from 'bus.BusService';
-
-import { DialogManagerContainer } from '@mail/components/dialog_manager_container/dialog_manager_container';
-import { ChatWindowManagerContainer } from '@mail/components/chat_window_manager_container/chat_window_manager_container';
 import { MessagingMenuContainer } from '@mail/components/messaging_menu_container/messaging_menu_container';
 import { insertAndReplace, replace } from '@mail/model/model_field_command';
-import { MessagingService } from '@mail/services/messaging/messaging';
-import { makeDeferred } from '@mail/utils/deferred';
 import { getMessagingComponent } from '@mail/utils/messaging_component';
 import { nextTick } from '@mail/utils/utils';
-import { DiscussWidget } from '@mail/widgets/discuss/discuss';
-import { addTimeControlToEnv } from '@mail/../tests/helpers/time_control';
+import { getAdvanceTime } from '@mail/../tests/helpers/time_control';
+import { getWebClientReady } from '@mail/../tests/helpers/webclient_setup';
 
-import core from 'web.core';
-import AbstractStorageService from 'web.AbstractStorageService';
-import RamStorage from 'web.RamStorage';
-import {
-    createView,
-    mock,
-} from 'web.test_utils';
-import Widget from 'web.Widget';
-import { browser } from '@web/core/browser/browser';
 import { registry } from '@web/core/registry';
 import { registerCleanup } from "@web/../tests/helpers/cleanup";
-import { getFixture, patchWithCleanup } from "@web/../tests/helpers/utils";
-import { createWebClient, getActionManagerServerData } from "@web/../tests/webclient/helpers";
+import { MockServer } from "@web/../tests/helpers/mock_server";
+import { getFixture, makeDeferred, patchWithCleanup } from "@web/../tests/helpers/utils";
+import { doAction, getActionManagerServerData } from "@web/../tests/webclient/helpers";
 
-import LegacyRegistry from "web.Registry";
-import MockServer from 'web.MockServer';
+import core from 'web.core';
 
-const { App, Component, EventBus } = owl;
+const { App, EventBus } = owl;
 const { afterNextRender } = App;
-const { addMockEnvironment } = mock;
-
 const modelDefinitionsPromise = new Promise(resolve => {
     QUnit.begin(() => resolve(getModelDefinitions()));
 });
@@ -59,44 +42,6 @@ function _createFakeDataTransfer(files) {
     };
 }
 
-/**
- * @private
- * @param {HTMLElement} target
- */
-async function mountChatWindowManagerContainer(target) {
-    const app = new App(ChatWindowManagerContainer, {
-        templates: window.__OWL_TEMPLATES__,
-        env: owl.Component.env,
-        dev: owl.Component.env.isDebug(),
-        translateFn: owl.Component.env._t,
-        translatableAttributes: ["data-tooltip"],
-    });
-    await app.mount(target);
-
-    registerCleanup(() => {
-        app.destroy();
-    });
-}
-
-/**
- * @private
- * @param {HTMLElement} target
- */
-async function mountDialogManagerContainer(target) {
-    const app = new App(DialogManagerContainer, {
-        templates: window.__OWL_TEMPLATES__,
-        env: owl.Component.env,
-        dev: owl.Component.env.isDebug(),
-        translateFn: owl.Component.env._t,
-        translatableAttributes: ["data-tooltip"],
-    });
-    await app.mount(target);
-
-    registerCleanup(() => {
-        app.destroy();
-    });
-}
-
 //------------------------------------------------------------------------------
 // Public: rendering timers
 //------------------------------------------------------------------------------
@@ -198,7 +143,7 @@ const VIEW_TYPE_TO_ARCH = {
  * server (creation, deletion, update of records...)
  */
  export async function startServer() {
-    const data = { ...TEST_USER_IDS };
+    const models = {};
     const views = {};
     const modelDefinitions = await modelDefinitionsPromise;
     const recordsToInsertRegistry = registry.category('mail.model.definitions').category('recordsToInsert');
@@ -208,7 +153,7 @@ const VIEW_TYPE_TO_ARCH = {
             // prevent tests from mutating the records.
             records.push(...JSON.parse(JSON.stringify(recordsToInsertRegistry.get(modelName))));
         }
-        data[modelName] = { fields: { ...fields }, records };
+        models[modelName] = { fields: { ...fields }, records };
 
         // generate default views for this model.
         for (const [viewType, viewArch] of Object.entries(VIEW_TYPE_TO_ARCH)) {
@@ -217,13 +162,16 @@ const VIEW_TYPE_TO_ARCH = {
     }
     pyEnv = new Proxy(
         {
+            getData() {
+                return this.mockServer.models;
+            },
+            getViews() {
+                return views;
+            },
             ...TEST_USER_IDS,
             get currentPartner() {
                 return this.mockServer.currentPartner;
             },
-            getViews() {
-                return views;
-            }
         },
         {
             get(target, name) {
@@ -305,7 +253,7 @@ const VIEW_TYPE_TO_ARCH = {
             },
          },
     );
-    pyEnv['mockServer'] = new MockServer(data, {});
+    pyEnv['mockServer'] = new MockServer({ models }, {});
     await pyEnv['mockServer'].setup();
     registerCleanup(() => pyEnv = undefined);
     return pyEnv;
@@ -366,7 +314,7 @@ function getAfterEvent({ messagingBus }) {
         clearTimeout(timeoutNoEvent);
         // If the event is triggered before the end of the async function,
         // ensure the function finishes its job before returning.
-        await funcRes;
+        return await funcRes;
     };
 }
 
@@ -499,7 +447,7 @@ function getCreateMessageComponent({ env, modelManager, target }) {
 
 function getCreateMessagingMenuComponent({ env, target }) {
     return async function createMessagingMenuComponent() {
-        return await createRootComponent({ env }, MessagingMenuContainer, { target });
+        return await createRootComponent(env, MessagingMenuContainer, { target });
     };
 }
 
@@ -527,7 +475,7 @@ function getCreateThreadViewComponent({ afterEvent, env, target }) {
                 'flex-flow': 'column',
                 height: '300px',
             });
-            target.append(div);
+            target.appendChild(div);
             actualTarget = div;
         } else {
             actualTarget = target;
@@ -553,67 +501,41 @@ function getCreateThreadViewComponent({ afterEvent, env, target }) {
     };
 }
 
-function getOpenDiscuss({ afterNextRender, discuss, selector, widget }) {
+function getOpenDiscuss(webClient, { context, params, ...props } = {}) {
     return async function openDiscuss() {
-        widget.do_push_state = () => {};
-        const discussWidget = new DiscussWidget(widget, discuss);
-        await discussWidget.appendTo($(selector));
-        await afterNextRender(() => discussWidget.on_attach_callback());
-        // Some changes in the models are made on mount, but these changes don't
-        // cause a rerender directly, they cause the model to fetch more data
-        // but we cannot wait for that data to come back as the model manager
-        // doesn't expose it. This means that in the following microticks, the
-        // data will come back from the server and cause a render. The following
-        // is a way for us to catch the render cascade caused by the data coming
-        // back and wait for it.
-        await afterNextRender(() => {
-            discussWidget.app.root.render();
-        });
-        return discussWidget;
+        const actionOpenDiscuss = {
+            // hardcoded actionId, required for discuss_container props validation.
+            id: 104,
+            context,
+            params,
+            tag: 'mail.action_discuss',
+            type: 'ir.actions.client',
+        };
+        await afterNextRender(() => doAction(webClient, actionOpenDiscuss, { props }));
     };
 }
 
+//------------------------------------------------------------------------------
+// Public: start function helpers
+//------------------------------------------------------------------------------
+
 /**
  * Main function used to make a mocked environment with mocked messaging env.
  *
  * @param {Object} [param0={}]
- * @param {string} [param0.arch] makes only sense when `param0.hasView` is set:
- *   the arch to use in createView.
- * @param {Object} [param0.archs]
- * @param {boolean} [param0.autoOpenDiscuss=false] determine whether mounted discuss should be
+ * @param {boolean} [param0.autoOpenDiscuss=false] determine if discuss should be
  *   open initially. Deprecated, call openDiscuss() instead.
- * @param {boolean} [param0.debug=false]
- * @param {Object} [param0.data] makes only sense when `param0.hasView` is set:
- *   the data to use in createView.
- * @param {Object} [param0.discuss={}] provide data that is passed to discuss widget
- * (= client action) as 2nd positional argument.
- * @param {Object} [param0.env={}]
- * @param {function} [param0.mockFetch]
+ * @param {Object} [param0.serverData] The data to pass to the webClient
+ * @param {Object} [param0.discuss={}] provide data that is passed to the discuss action.
+ * @param {Object} [param0.legacyServices]
+ * @param {Object} [param0.services]
  * @param {function} [param0.mockRPC]
- * @param {boolean} [param0.hasWebClient=false] if set, use
- *   createWebClient
  * @param {boolean} [param0.hasTimeControl=false] if set, all flow of time
- *   with `env.browser.setTimeout` are fully controlled by test itself.
- *     @see addTimeControlToEnv that adds `advanceTime` function in
- *     `env.testUtils`.
- * @param {boolean} [param0.hasView=false] if set, use createView to create a
- *   view instead of a generic widget.
+ *   with `messaging.browser.setTimeout` are fully controlled by test itself.
  * @param {integer} [param0.loadingBaseDelayDuration=0]
  * @param {Deferred|Promise} [param0.messagingBeforeCreationDeferred=Promise.resolve()]
  *   Deferred that let tests block messaging creation and simulate resolution.
  *   Useful for testing working components when messaging is not yet created.
- * @param {string} [param0.model] makes only sense when `param0.hasView` is set:
- *   the model to use in createView.
- * @param {integer} [param0.res_id] makes only sense when `param0.hasView` is set:
- *   the res_id to use in createView.
- * @param {Object} [param0.services]
- * @param {Object} [param0.session]
- * @param {Element} [param0.target] if provided, the component will be mounted inside
- *   that element (only used if `params0.hasWebClient` is true)
- * @param {Object} [param0.View] makes only sense when `param0.hasView` is set:
- *   the View class to use in createView.
- * @param {Object} [param0.viewOptions] makes only sense when `param0.hasView`
- *   is set: the view options to use in createView.
  * @param {Object} [param0.waitUntilEvent]
  * @param {String} [param0.waitUntilEvent.eventName]
  * @param {String} [param0.waitUntilEvent.message]
@@ -631,7 +553,6 @@ function getOpenDiscuss({ afterNextRender, discuss, selector, widget }) {
  *   as param of `messagingBeforeCreationDeferred`. To make sure messaging is
  *   not initialized, test should mock RPC `mail/init_messaging` and block its
  *   resolution.
- * @param {...Object} [param0.kwargs]
  * @throws {Error} in case some provided parameters are wrong, such as
  *   `waitUntilMessagingCondition`.
  * @returns {Object}
@@ -643,189 +564,19 @@ async function start(param0 = {}) {
         throttle: func => func,
     });
     const {
-        autoOpenDiscuss = false,
+        autoOpenDiscuss,
         discuss = {},
-        env: providedEnv = {},
-        hasWebClient = false,
-        hasTimeControl = false,
-        hasView = false,
-        loadingBaseDelayDuration = 0,
-        messagingBeforeCreationDeferred = Promise.resolve(),
-        target: webclientTarget = getFixture(),
+        hasTimeControl,
         waitUntilEvent,
         waitUntilMessagingCondition = 'initialized',
     } = param0;
+    const target = param0['target'] || getFixture();
+    param0['target'] = target;
     if (!['none', 'created', 'initialized'].includes(waitUntilMessagingCondition)) {
         throw Error(`Unknown parameter value ${waitUntilMessagingCondition} for 'waitUntilMessaging'.`);
     }
-    delete param0.autoOpenDiscuss;
-    delete param0.env;
-    delete param0.hasWebClient;
-    delete param0.hasTimeControl;
-    delete param0.hasView;
-    delete param0.target;
     const messagingBus = new EventBus();
-    const { debug = false } = param0;
     const testSetupDoneDeferred = makeDeferred();
-    let env = {
-        ...providedEnv,
-        browser: {
-            ...providedEnv.browser,
-            innerWidth: browser.innerWidth,
-            innerHeight: browser.innerHeight,
-        },
-        device: {
-            ...providedEnv.device,
-            isMobile: owl.Component.env.device.isMobile,
-        },
-    };
-    env.session = Object.assign(
-        {
-            is_bound: Promise.resolve(),
-            url: s => s,
-        },
-        env.session
-    );
-    env.isDebug = env.isDebug || (() => true);
-    if (hasTimeControl) {
-        env = addTimeControlToEnv(env);
-    }
-
-    const services = Object.assign({}, {
-        bus_service: BusService.extend({
-            _beep() {}, // Do nothing
-            _poll() {}, // Do nothing
-            _registerWindowUnload() {}, // Do nothing
-            isOdooFocused() {
-                return true;
-            },
-            updateOption() {},
-        }),
-        local_storage: AbstractStorageService.extend({ storage: new RamStorage() }),
-        messaging: MessagingService.extend({
-            // test specific values
-            messagingValues: {
-                autofetchPartnerImStatus: false,
-                disableAnimation: true,
-                loadingBaseDelayDuration,
-                messagingBus,
-            },
-            /**
-             * Override to ensure tests run in debug mode to catch all potential
-             * programming errors and provide better message when they happen.
-             */
-            init(...args) {
-                this._super(...args);
-                this.modelManager.isDebug = true;
-            },
-            /**
-             * Override:
-             * - to ensure the test setup is complete before starting otherwise
-             *   for example the mock server might not be ready yet at init
-             *   messaging,
-             * - to add control on when messaging is created, useful to test
-             *   spinners and race conditions.
-             *
-             * @override
-             */
-            async start() {
-                const _super = this._super.bind(this);
-                await testSetupDoneDeferred;
-                await messagingBeforeCreationDeferred;
-                _super();
-            },
-        }),
-    }, param0.services);
-
-    if (!param0.data && (!param0.serverData || !param0.serverData.models)) {
-        pyEnv = pyEnv || await startServer();
-        const data = pyEnv.mockServer.data;
-        Object.assign(data, TEST_USER_IDS);
-        if (hasWebClient) {
-            param0.serverData = param0.serverData || getActionManagerServerData();
-            param0.serverData.models = data;
-            param0.serverData.views = { ...pyEnv.getViews(), ...param0.serverData.views };
-        } else {
-            param0.data = data;
-        }
-    }
-
-    const kwargs = Object.assign({}, param0, {
-        archs: Object.assign({}, {
-            'mail.message,false,search': '<search/>'
-        }, param0.archs),
-        debug: param0.debug || false,
-        services: Object.assign({}, services, param0.services),
-    }, { env });
-    let widget;
-    let mockServer;
-    let testEnv;
-    const selector = debug ? 'body' : '#qunit-fixture';
-    if (hasView) {
-        widget = await createView(kwargs);
-    } else if (hasWebClient) {
-        let serverData;
-        if (!kwargs.serverData) {
-            serverData = getActionManagerServerData();
-        } else {
-            serverData = kwargs.serverData;
-            delete kwargs.serverData;
-        }
-
-        if (kwargs.actions) {
-            const actions = {};
-            kwargs.actions.forEach((act) => {
-                actions[act.xml_id || act.id] = act;
-            });
-            Object.assign(serverData.actions, actions);
-            delete kwargs.actions;
-        }
-
-        Object.assign(serverData.views, kwargs.archs);
-        delete kwargs.archs;
-
-        Object.assign(serverData.models, kwargs.data);
-        delete kwargs.data;
-
-        const mockRPC = kwargs.mockRPC;
-        delete kwargs.mockRPC;
-
-        if (kwargs.services) {
-            const serviceRegistry = kwargs.serviceRegistry = new LegacyRegistry();
-            for (const sname in kwargs.services) {
-                serviceRegistry.add(sname, kwargs.services[sname]);
-            }
-            delete kwargs.services;
-        }
-
-        const legacyParams = kwargs;
-        legacyParams.withLegacyMockServer = true;
-        legacyParams.env = env;
-
-        widget = await createWebClient({ target: webclientTarget, serverData, mockRPC, legacyParams });
-    } else {
-        const Parent = Widget.extend({ do_push_state() {} });
-        const parent = new Parent();
-        mockServer = await addMockEnvironment(parent, kwargs);
-        widget = new Widget(parent);
-        await widget.appendTo($(selector));
-        Object.assign(widget, {
-            destroy() {
-                delete widget.destroy;
-                parent.destroy();
-            },
-        });
-    }
-    // get the final test env after execution of createView/createWebClient/addMockEnvironment
-    testEnv = Component.env;
-    patchWithCleanup(browser, {
-        fetch: testEnv.browser.fetch,
-    });
-    // link the pyEnv to the actual mockServer after execution of createView/createWebClient/addMockEnvironment
-    if (pyEnv) {
-        pyEnv.mockServer = MockServer.currentMockServer;
-        mockServer = pyEnv.mockServer;
-    }
     const afterEvent = getAfterEvent({ messagingBus });
     let waitUntilEventPromise;
     if (waitUntilEvent) {
@@ -834,22 +585,15 @@ async function start(param0 = {}) {
         testSetupDoneDeferred.resolve();
         waitUntilEventPromise = Promise.resolve();
     }
-    const result = {
-        afterEvent,
-        env: testEnv,
-        mockServer,
-        pyEnv,
-        widget,
-        wowlEnv: hasWebClient ? widget.env : undefined,
-    };
-    if (hasTimeControl) {
-        result['advanceTime'] = env.testUtils.advanceTime;
-    }
-    const { modelManager } = testEnv.services.messaging;
-    registerCleanup(async() => {
-        if (!hasWebClient) {
-            widget.destroy();
-        }
+
+    pyEnv = await getPyEnv();
+    param0.serverData = param0.serverData || getActionManagerServerData();
+    param0.serverData.models = { ...pyEnv.getData(), ...param0.serverData.models };
+    param0.serverData.views = { ...pyEnv.getViews(), ...param0.serverData.views };
+    const webClient = await getWebClientReady({ ...param0, messagingBus, testSetupDoneDeferred });
+
+    const { modelManager } = webClient.env.services.messaging;
+    registerCleanup(async () => {
         await modelManager.messagingInitializedPromise;
         modelManager.messaging.delete();
     });
@@ -860,30 +604,37 @@ async function start(param0 = {}) {
         await modelManager.messagingCreatedPromise;
         await modelManager.messagingInitializedPromise;
     }
-    const openDiscuss = getOpenDiscuss({ afterNextRender, discuss, selector, widget });
+    const openDiscuss = getOpenDiscuss(webClient, discuss);
     if (autoOpenDiscuss) {
-        const discussWidget = await openDiscuss();
-        result['discussWidget'] = discussWidget;
+        await openDiscuss();
     }
-    const target = hasWebClient ? webclientTarget : widget.el;
-    await mountChatWindowManagerContainer(target);
-    await mountDialogManagerContainer(target);
+    // link the pyEnv to the actual mockServer after execution of createWebClient.
+    pyEnv.mockServer = MockServer.currentMockServer;
+    const openView = async (action, options) => {
+        action['type'] = action['type'] || 'ir.actions.act_window';
+        return doAction(webClient, action, { props: options });
+    };
     await waitUntilEventPromise;
     return {
-        ...result,
+        advanceTime: hasTimeControl ? getAdvanceTime() : undefined,
+        afterEvent,
         afterNextRender,
         click: getClick({ afterNextRender }),
-        createChatterContainerComponent: getCreateChatterContainerComponent({ afterEvent, env: testEnv, target }),
-        createComposerComponent: getCreateComposerComponent({ env: testEnv, modelManager, target }),
-        createComposerSuggestionComponent: getCreateComposerSuggestionComponent({ env: testEnv, modelManager, target }),
-        createMessageComponent: getCreateMessageComponent({ env: testEnv, modelManager, target }),
-        createMessagingMenuComponent: getCreateMessagingMenuComponent({ env: testEnv, target }),
-        createNotificationListComponent: getCreateNotificationListComponent({ env: testEnv, modelManager, target }),
-        createRootMessagingComponent: (componentName, props) => createRootMessagingComponent(testEnv, componentName, { props, target }),
-        createThreadViewComponent: getCreateThreadViewComponent({ afterEvent, env: testEnv, target }),
+        createChatterContainerComponent: getCreateChatterContainerComponent({ afterEvent, env: webClient.env, target }),
+        createComposerComponent: getCreateComposerComponent({ env: webClient.env, modelManager, target }),
+        createComposerSuggestionComponent: getCreateComposerSuggestionComponent({ env: webClient.env, modelManager, target }),
+        createMessageComponent: getCreateMessageComponent({ env: webClient.env, modelManager, target }),
+        createMessagingMenuComponent: getCreateMessagingMenuComponent({ env: webClient.env, target }),
+        createNotificationListComponent: getCreateNotificationListComponent({ env: webClient.env, modelManager, target }),
+        createRootMessagingComponent: (componentName, props) => createRootMessagingComponent(webClient.env, componentName, { props, target }),
+        createThreadViewComponent: getCreateThreadViewComponent({ afterEvent, env: webClient.env, target }),
+        env: webClient.env,
         insertText,
         messaging: modelManager.messaging,
         openDiscuss,
+        openView,
+        pyEnv,
+        webClient,
     };
 }
 
diff --git a/addons/mail/static/tests/helpers/time_control.js b/addons/mail/static/tests/helpers/time_control.js
index 78ca6a14a61..600735b5aa8 100644
--- a/addons/mail/static/tests/helpers/time_control.js
+++ b/addons/mail/static/tests/helpers/time_control.js
@@ -3,17 +3,9 @@
 import { nextTick } from '@mail/utils/utils';
 
 import { browser } from '@web/core/browser/browser';
-import { patchWithCleanup } from '@web/../tests/helpers/utils';
+import { patchWithCleanup } from "@web/../tests/helpers/utils";
 
-/**
- * @param {Object} [providedEnv={}]
- * @returns {Object}
- */
- export function addTimeControlToEnv(providedEnv = {}) {
-    const env = { ...providedEnv };
-    if (!env.browser) {
-        env.browser = {};
-    }
+export function getAdvanceTime() {
     // list of timeout ids that have timed out.
     let timedOutIds = [];
     // key: timeoutId, value: func + remaining duration
@@ -39,31 +31,24 @@ import { patchWithCleanup } from '@web/../tests/helpers/utils';
             return timeoutId;
         },
     });
-    if (!env.testUtils) {
-        env.testUtils = {};
-    }
-    Object.assign(env.testUtils, {
-        advanceTime: async duration => {
-            await nextTick();
-            for (const id of timeouts.keys()) {
-                const timeout = timeouts.get(id);
-                if (timeout.isTimedOut) {
-                    continue;
-                }
-                timeout.duration = Math.max(timeout.duration - duration, 0);
-                if (timeout.duration === 0) {
-                    timedOutIds.push(id);
-                }
+    return async function (duration) {
+        await nextTick();
+        for (const id of timeouts.keys()) {
+            const timeout = timeouts.get(id);
+            if (timeout.isTimedOut) {
+                continue;
             }
-            while (timedOutIds.length > 0) {
-                const id = timedOutIds.shift();
-                const timeout = timeouts.get(id);
-                timeouts.delete(id);
-                timeout.func();
-                await nextTick();
+            timeout.duration = Math.max(timeout.duration - duration, 0);
+            if (timeout.duration === 0) {
+                timedOutIds.push(id);
             }
+        }
+        while (timedOutIds.length > 0) {
+            const id = timedOutIds.shift();
+            const timeout = timeouts.get(id);
+            timeouts.delete(id);
+            timeout.func();
             await nextTick();
-        },
-    });
-    return env;
+        }
+    };
 }
diff --git a/addons/mail/static/tests/helpers/webclient_setup.js b/addons/mail/static/tests/helpers/webclient_setup.js
new file mode 100644
index 00000000000..6c10d2cca2b
--- /dev/null
+++ b/addons/mail/static/tests/helpers/webclient_setup.js
@@ -0,0 +1,174 @@
+/** @odoo-module **/
+
+import { legacyBusService } from '@bus/js/services/legacy/legacy_bus_service';
+
+import BusService from 'bus.BusService';
+
+import { ChatWindowManagerContainer } from '@mail/components/chat_window_manager_container/chat_window_manager_container';
+import { DialogManagerContainer } from '@mail/components/dialog_manager_container/dialog_manager_container';
+import { DiscussContainer } from '@mail/components/discuss_container/discuss_container';
+import { messagingService } from '@mail/services/messaging_service';
+import { makeMessagingToLegacyEnv } from '@mail/utils/make_messaging_to_legacy_env';
+
+import { registry } from '@web/core/registry';
+import { patchWithCleanup } from "@web/../tests/helpers/utils";
+import { createWebClient } from "@web/../tests/webclient/helpers";
+
+import AbstractStorageService from 'web.AbstractStorageService';
+import RamStorage from 'web.RamStorage';
+import LegacyRegistry from 'web.Registry';
+
+const WEBCLIENT_LOAD_ROUTES = [
+    '/web/webclient/load_menus',
+    '/web/dataset/call_kw/res.users/load_views',
+];
+const WEBCLIENT_PARAMETER_NAMES = new Set(['legacyParams', 'mockRPC', 'serverData', 'target', 'webClientClass']);
+const SERVICES_PARAMETER_NAMES = new Set([
+    'legacyServices', 'loadingBaseDelayDuration', 'messagingBeforeCreationDeferred',
+    'messagingBus', 'services', 'testSetupDoneDeferred',
+]);
+
+/**
+ * Add required components to the main component registry.
+ */
+ function setupMainComponentRegistry() {
+    const mainComponentRegistry = registry.category('main_components');
+    mainComponentRegistry.add('ChatWindowManagerContainer', { Component: ChatWindowManagerContainer });
+    mainComponentRegistry.add('DialogManagerContainer', { Component: DialogManagerContainer });
+    registry.category('actions').add('mail.action_discuss', DiscussContainer);
+}
+
+/**
+ * Setup both legacy and new service registries.
+ *
+ * @param {Object} param0
+ * @param {Object} [param0.services]
+ * @param {Object} [param0.legacyServices]
+ * @param {number} [param0.loadingBaseDelayDuration=0]
+ * @param {Promise} [param0.messagingBeforeCreationDeferred=Promise.resolve()]
+ *   Deferred that let tests block messaging creation and simulate resolution.
+ *   Useful for testing components behavior when messaging is not yet created.
+ * @param {EventBus} [param0.messagingBus]
+ * @param {Promise} [param0.testSetupDoneDeferred] The Promise to whose revolution has to be
+ * waited before starting the messaging service.
+ * @returns {LegacyRegistry} The registry containing all the legacy services that will be passed
+ * to the webClient as a legacy parameter.
+ */
+function setupMessagingServiceRegistries({
+    legacyServices,
+    loadingBaseDelayDuration = 0,
+    messagingBeforeCreationDeferred = Promise.resolve(),
+    messagingBus,
+    services,
+    testSetupDoneDeferred,
+ }) {
+    const serviceRegistry = registry.category('services');
+    const legacyServiceRegistry = new LegacyRegistry();
+    legacyServices = {
+        bus_service: BusService.extend({
+            _beep() {}, // Do nothing
+            _poll() {}, // Do nothing
+            _registerWindowUnload() {}, // Do nothing
+            isOdooFocused() {
+                return true;
+            },
+            updateOption() {},
+        }),
+        local_storage: AbstractStorageService.extend({ storage: new RamStorage() }),
+        ...legacyServices,
+    };
+
+    patchWithCleanup(messagingService, {
+        async _startModelManager() {
+            const _super = this._super.bind(this);
+            await testSetupDoneDeferred;
+            await messagingBeforeCreationDeferred;
+            return _super(...arguments);
+        },
+    });
+
+    const messagingValues = {
+        start() {
+            return {
+                autofetchPartnerImStatus: false,
+                disableAnimation: true,
+                loadingBaseDelayDuration,
+                messagingBus,
+            };
+        }
+    };
+
+    services = {
+        messagingValues,
+        ...services,
+    };
+    // during tests, we need to wait for the legacyBusService to be added  before adding the messaging
+    // service to the registry or it will result in an error during the webClient creation.
+    const addMessagingToRegistryFn = ev => {
+        const { key, operation } = ev.detail;
+        if (key === 'legacy_bus_service' && operation === 'add') {
+            serviceRegistry.add('messaging', messagingService);
+            serviceRegistry.add('messaging_service_to_legacy_env', makeMessagingToLegacyEnv(owl.Component.env));
+            serviceRegistry.removeEventListener('UPDATE', addMessagingToRegistryFn);
+        }
+    };
+    serviceRegistry.addEventListener('UPDATE', addMessagingToRegistryFn);
+
+    Object.entries(services).forEach(([serviceName, service]) => {
+        serviceRegistry.add(serviceName, service);
+    });
+    Object.entries(legacyServices).forEach(([serviceName, service]) => {
+        legacyServiceRegistry.add(serviceName, service);
+    });
+
+    return legacyServiceRegistry;
+}
+
+/**
+ * Creates a properly configured instance of WebClient, with the messaging service and all it's
+ * dependencies initialized.
+ *
+ * @param {Object} param0
+ * @param {Object} [param0.serverData]
+ * @param {Object} [param0.services]
+ * @param {Object} [param0.legacyServices]
+ * @param {Object} [param0.legacyParams={}]
+ * @param {Object} [param0.loadingBaseDelayDuration]
+ * @param {Object} [param0.messagingBeforeCreationDeferred]
+ * @param {Promise} [param0.testSetupDoneDeferred] The Promise to whose revolution has to be
+ * waited before starting the messaging service.
+ * @param {EventBus} [param0.messagingBus] The event bus to be used by messaging.
+ * @returns {WebClient}
+ */
+ async function getWebClientReady(param0) {
+    setupMainComponentRegistry();
+
+    const servicesParameters = {};
+    const param0Entries = Object.entries(param0);
+    for (const [parameterName, value] of param0Entries) {
+        if (SERVICES_PARAMETER_NAMES.has(parameterName)) {
+            servicesParameters[parameterName] = value;
+        }
+    }
+    const legacyServiceRegistry = setupMessagingServiceRegistries(servicesParameters);
+
+    const webClientParameters = {};
+    for (const [parameterName, value] of param0Entries) {
+        if (WEBCLIENT_PARAMETER_NAMES.has(parameterName)) {
+            webClientParameters[parameterName] = value;
+        }
+    }
+    webClientParameters.legacyParams = {
+        legacyServicesToDeployInWowlEnv: {
+            legacy_bus_service: legacyBusService,
+        },
+        serviceRegistry: legacyServiceRegistry,
+        ...webClientParameters.legacyParams,
+    };
+    return createWebClient(webClientParameters);
+}
+
+export {
+    getWebClientReady,
+    WEBCLIENT_LOAD_ROUTES,
+};
diff --git a/addons/mail/static/tests/qunit_suite_tests/chatter_tests.js b/addons/mail/static/tests/qunit_suite_tests/chatter_tests.js
index 1f96a727c1b..0c66213ebb4 100644
--- a/addons/mail/static/tests/qunit_suite_tests/chatter_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/chatter_tests.js
@@ -1,10 +1,10 @@
 /** @odoo-module **/
 
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
+import { WEBCLIENT_LOAD_ROUTES } from '@mail/../tests/helpers/webclient_setup';
 
-import FormView from 'web.FormView';
-import ListView from 'web.ListView';
 import testUtils from 'web.test_utils';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('Chatter');
@@ -13,19 +13,25 @@ QUnit.test('list activity widget with no activity', async function (assert) {
     assert.expect(4);
 
     const pyEnv = await startServer();
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: '<list><field name="activity_ids" widget="list_activity"/></list>',
-        mockRPC: function (route) {
-            if (!['/mail/init_messaging', '/mail/load_message_failures'].includes(route)) {
+    const views = {
+        'res.users,false,list': '<list><field name="activity_ids" widget="list_activity"/></list>',
+    };
+    const { openView } = await start({
+        mockRPC: function (route, args) {
+            if (
+                args.method !== 'get_views' &&
+                !['/mail/init_messaging', '/mail/load_message_failures', ...WEBCLIENT_LOAD_ROUTES].includes(route)
+            ) {
                 assert.step(route);
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
         session: { uid: pyEnv.currentUserId },
     });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
+    });
 
     assert.containsOnce(document.body, '.o_mail_activity .o_activity_color_default');
     assert.strictEqual(document.querySelector('.o_activity_summary').innerText, '');
@@ -55,18 +61,24 @@ QUnit.test('list activity widget with activities', async function (assert) {
         activity_summary: false,
         activity_type_id: mailActivityTypeId2,
     });
+    const views = {
+        'res.users,false,list': '<list><field name="activity_ids" widget="list_activity"/></list>',
+    };
 
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: '<list><field name="activity_ids" widget="list_activity"/></list>',
-        mockRPC: function (route) {
-            if (!['/mail/init_messaging', '/mail/load_message_failures'].includes(route)) {
+    const { openView } = await start({
+        mockRPC: function (route, args) {
+            if (
+                args.method !== 'get_views' &&
+                !['/mail/init_messaging', '/mail/load_message_failures', ...WEBCLIENT_LOAD_ROUTES].includes(route)
+            ) {
                 assert.step(route);
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
     });
 
     const firstRow = document.querySelector('.o_data_row');
@@ -95,17 +107,23 @@ QUnit.test('list activity widget with exception', async function (assert) {
         activity_exception_icon: 'fa-warning',
     });
 
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: '<list><field name="activity_ids" widget="list_activity"/></list>',
-        mockRPC: function (route) {
-            if (!['/mail/init_messaging', '/mail/load_message_failures'].includes(route)) {
+    const views = {
+        'res.users,false,list': '<list><field name="activity_ids" widget="list_activity"/></list>',
+    };
+    const { openView } = await start({
+        mockRPC: function (route, args) {
+            if (
+                args.method !== 'get_views' &&
+                !['/mail/init_messaging', '/mail/load_message_failures', ...WEBCLIENT_LOAD_ROUTES].includes(route)
+            ) {
                 assert.step(route);
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
     });
 
     assert.containsOnce(document.body, '.o_activity_color_today.text-warning.fa-warning');
@@ -146,16 +164,15 @@ QUnit.test('list activity widget: open dropdown', async function (assert) {
         activity_type_id: mailActivityTypeId2,
     });
 
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: `
-            <list>
-                <field name="activity_ids" widget="list_activity"/>
-            </list>`,
+    const views = {
+        'res.users,false,list': '<list><field name="activity_ids" widget="list_activity"/></list>',
+    };
+    const { env, openView } = await start({
         mockRPC: function (route, args) {
-            if (!['/mail/init_messaging', '/mail/load_message_failures'].includes(route)) {
+            if (
+                args.method !== 'get_views' &&
+                !['/mail/init_messaging', '/mail/load_message_failures', ...WEBCLIENT_LOAD_ROUTES].includes(route)
+            ) {
                 assert.step(args.method || route);
             }
             if (args.method === 'action_feedback') {
@@ -165,14 +182,21 @@ QUnit.test('list activity widget: open dropdown', async function (assert) {
                     activity_summary: 'Meet FP',
                     activity_type_id: mailActivityTypeId1,
                 });
-                return Promise.resolve();
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
             }
-            return this._super(route, args);
         },
-        intercepts: {
-            switch_view: () => assert.step('switch_view'),
+        serverData: { views },
+    });
+    patchWithCleanup(env.services.action, {
+        switchView() {
+            assert.step('switch_view');
         },
     });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
+    });
 
     assert.strictEqual(document.querySelector('.o_activity_summary').innerText, 'Call with Al');
 
@@ -236,13 +260,18 @@ QUnit.test('list activity exception widget with activity', async function (asser
         activity_exception_decoration: 'warning',
         activity_exception_icon: 'fa-warning',
     });
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: '<tree>' +
-                '<field name="activity_exception_decoration" widget="activity_exception"/> ' +
-            '</tree>',
+    const views = {
+        'res.users,false,list':
+            `<tree>
+                <field name="activity_exception_decoration" widget="activity_exception"/>
+            </tree>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
     });
 
     assert.containsN(document.body, '.o_data_row', 2, "should have two records");
@@ -274,15 +303,18 @@ QUnit.test('list activity widget: done the activity with "ENTER" keyboard shortc
         activity_summary: 'Call with Al',
         activity_type_id: mailActivityTypeId1,
     });
-
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: `
-            <list>
+    const views = {
+        'res.users,false,list':
+            `<list>
                 <field name="activity_ids" widget="list_activity"/>
             </list>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
     });
 
     await testUtils.dom.click(document.querySelector('.o_activity_btn span'));
@@ -322,19 +354,24 @@ QUnit.test('list activity widget: done and schedule the next activity with "ENTE
         activity_type_id: mailActivityTypeId1,
     });
 
-    await start({
-        hasView: true,
-        View: ListView,
-        model: 'res.users',
-        arch: `
-            <list>
+    const views = {
+        'res.users,false,list':
+            `<list>
                 <field name="activity_ids" widget="list_activity"/>
             </list>`,
-        intercepts: {
-            do_action: function (ev) {
-                assert.strictEqual(ev.data.action.name, "Schedule an Activity", 'should do a do_action with correct parameters');
-            },
-        },
+    };
+    const { env, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.users',
+        views: [[false, 'list']],
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
+            assert.strictEqual(action.name, "Schedule an Activity", 'should do a do_action with correct parameters');
+            return this._super(...arguments);
+        }
     });
 
     await testUtils.dom.click(document.querySelector('.o_activity_btn span'));
@@ -359,32 +396,35 @@ QUnit.test('fieldmany2many tags email (edition)', async function (assert) {
     const mailMessageId1 = pyEnv['mail.message'].create({
         partner_ids: [resPartnerId1],
     });
-
-    await start({
-        hasView: true,
-        View: FormView,
-        model: 'mail.message',
-        res_id: mailMessageId1,
-        arch: '<form string="Partners">' +
+    const views = {
+        'mail.message,false,form':
+            '<form string="Partners">' +
                 '<sheet>' +
                     '<field name="body"/>' +
                     '<field name="partner_ids" widget="many2many_tags_email"/>' +
                 '</sheet>' +
             '</form>',
-        viewOptions: {
-            mode: 'edit',
-        },
+        'res.partner,false,form': '<form string="Types"><field name="name"/><field name="email"/></form>',
+    };
+    var { openView } = await start({
+        serverData: { views },
         mockRPC: function (route, args) {
             if (args.method === 'read' && args.model === 'res.partner') {
                 assert.step(JSON.stringify(args.args[0]));
                 assert.ok(args.args[1].includes('email'), "should read the email");
             }
-            return this._super.apply(this, arguments);
-        },
-        archs: {
-            'res.partner,false,form': '<form string="Types"><field name="name"/><field name="email"/></form>',
         },
     });
+    await openView(
+        {
+            res_id: mailMessageId1,
+            res_model: 'mail.message',
+            views: [[false, 'form']],
+        },
+        {
+            mode: 'edit',
+        },
+    );
 
     assert.verifySteps([`[${resPartnerId1}]`]);
     assert.containsOnce(document.body, '.o_field_many2manytags[name="partner_ids"] .badge.o_tag_color_0',
@@ -428,13 +468,16 @@ QUnit.test('many2many_tags_email widget can load more than 40 records', async fu
     const mailMessageId1 = pyEnv['mail.message'].create({
         partner_ids: messagePartnerIds,
     });
-
-    const { click } = await start({
-        hasView: true,
-        View: FormView,
-        model: 'mail.message',
-        arch: '<form><field name="partner_ids" widget="many2many_tags"/></form>',
+    const views = {
+        'mail.message,false,form': '<form><field name="partner_ids" widget="many2many_tags"/></form>',
+    };
+    var { click, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
         res_id: mailMessageId1,
+        res_model: 'mail.message',
+        views: [[false, 'form']],
     });
 
     assert.strictEqual(document.querySelectorAll('.o_field_widget[name="partner_ids"] .badge').length, 100);
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/activity_mark_done_popover_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/activity_mark_done_popover_tests.js
index 2fb59a60b7b..c462fdd84ed 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/activity_mark_done_popover_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/activity_mark_done_popover_tests.js
@@ -2,7 +2,7 @@
 
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -129,13 +129,13 @@ QUnit.test('activity mark done popover mark done without feedback', async functi
                 assert.strictEqual(args.args[0][0], mailActivityId1);
                 assert.strictEqual(args.kwargs.attachment_ids.length, 0);
                 assert.notOk(args.kwargs.feedback);
-                return;
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
             }
             if (route === '/web/dataset/call_kw/mail.activity/unlink') {
                 // 'unlink' on non-existing record raises a server crash
                 throw new Error("'unlink' RPC on activity must not be called (already unlinked from mark as done)");
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -170,13 +170,13 @@ QUnit.test('activity mark done popover mark done with feedback', async function
                 assert.strictEqual(args.args[0][0], mailActivityId1);
                 assert.strictEqual(args.kwargs.attachment_ids.length, 0);
                 assert.strictEqual(args.kwargs.feedback, 'This task is done');
-                return;
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
             }
             if (route === '/web/dataset/call_kw/mail.activity/unlink') {
                 // 'unlink' on non-existing record raises a server crash
                 throw new Error("'unlink' RPC on activity must not be called (already unlinked from mark as done)");
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -198,11 +198,6 @@ QUnit.test('activity mark done popover mark done with feedback', async function
 QUnit.test('activity mark done popover mark done and schedule next', async function (assert) {
     assert.expect(6);
 
-    const bus = new Bus();
-    bus.on('do-action', null, () => {
-            assert.step('activity_action');
-            throw new Error("The do-action event should not be triggered when the route doesn't return an action");
-    });
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create();
     const mailActivityId1 = pyEnv['mail.activity'].create({
@@ -211,7 +206,7 @@ QUnit.test('activity mark done popover mark done and schedule next', async funct
         res_id: resPartnerId1,
         res_model: 'res.partner',
     });
-    const { click, createChatterContainerComponent } = await start({
+    const { click, env, createChatterContainerComponent } = await start({
         async mockRPC(route, args) {
             if (route === '/web/dataset/call_kw/mail.activity/action_feedback_schedule_next') {
                 assert.step('action_feedback_schedule_next');
@@ -225,9 +220,13 @@ QUnit.test('activity mark done popover mark done and schedule next', async funct
                 // 'unlink' on non-existing record raises a server crash
                 throw new Error("'unlink' RPC on activity must not be called (already unlinked from mark as done)");
             }
-            return this._super(...arguments);
         },
-        env: { bus },
+    });
+    patchWithCleanup(env.services.action, {
+        doAction() {
+            assert.step('activity_action');
+            throw new Error("The do-action event should not be triggered when the route doesn't return an action");
+        },
     });
     await createChatterContainerComponent({
         threadId: resPartnerId1,
@@ -248,15 +247,6 @@ QUnit.test('activity mark done popover mark done and schedule next', async funct
 QUnit.test('[technical] activity mark done & schedule next with new action', async function (assert) {
     assert.expect(3);
 
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
-            assert.step('activity_action');
-            assert.deepEqual(
-                action,
-                { type: 'ir.actions.act_window' },
-                "The content of the action should be correct"
-            );
-    });
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create();
     pyEnv['mail.activity'].create({
@@ -265,13 +255,21 @@ QUnit.test('[technical] activity mark done & schedule next with new action', asy
         res_id: resPartnerId1,
         res_model: 'res.partner',
     });
-    const { click, createChatterContainerComponent } = await start({
-        env: { bus },
+    const { click, createChatterContainerComponent, env } = await start({
         async mockRPC(route, args) {
             if (route === '/web/dataset/call_kw/mail.activity/action_feedback_schedule_next') {
                 return { type: 'ir.actions.act_window' };
             }
-            return this._super(...arguments);
+        },
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
+            assert.step('activity_action');
+            assert.deepEqual(
+                action,
+                { type: 'ir.actions.act_window' },
+                "The content of the action should be correct"
+            );
         },
     });
     await createChatterContainerComponent({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/activity_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/activity_tests.js
index 03a3164064e..370b95a8fe3 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/activity_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/activity_tests.js
@@ -2,8 +2,8 @@
 
 import { afterNextRender, start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
 import { date_to_str } from 'web.time';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -602,8 +602,9 @@ QUnit.test('activity with mail template: preview mail', async function (assert)
         res_id: resPartnerId1,
         res_model: 'res.partner',
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { createChatterContainerComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.context.default_res_id,
@@ -634,8 +635,8 @@ QUnit.test('activity with mail template: preview mail', async function (assert)
                 "mail.compose.message",
                 'Action should have "mail.compose.message" as res_model'
             );
+        },
     });
-    const { createChatterContainerComponent } = await start({ env: { bus } });
     await createChatterContainerComponent({
         threadId: resPartnerId1,
         threadModel: 'res.partner',
@@ -678,9 +679,8 @@ QUnit.test('activity with mail template: send mail', async function (assert) {
                 assert.strictEqual(args.args[0].length, 1);
                 assert.strictEqual(args.args[0][0], resPartnerId1);
                 assert.strictEqual(args.args[1], mailTemplateId1);
-                return;
-            } else {
-                return this._super(...arguments);
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
             }
         },
     });
@@ -835,8 +835,9 @@ QUnit.test('activity click on edit', async function (assert) {
         res_id: resPartnerId1,
         res_model: 'res.partner',
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { click, createChatterContainerComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.context.default_res_id,
@@ -863,8 +864,9 @@ QUnit.test('activity click on edit', async function (assert) {
                 mailActivityId1,
                 'Action should have activity id as res_id'
             );
+            return this._super(...arguments);
+        },
     });
-    const { createChatterContainerComponent } = await start({ env: { bus } });
     await createChatterContainerComponent({
         threadId: resPartnerId1,
         threadModel: 'res.partner',
@@ -880,7 +882,7 @@ QUnit.test('activity click on edit', async function (assert) {
         "should have activity edit button"
     );
 
-    document.querySelector('.o_Activity_editButton').click();
+    await click('.o_Activity_editButton');
     assert.verifySteps(
         ['do_action'],
         "should have called 'schedule activity' action correctly"
@@ -898,8 +900,9 @@ QUnit.test('activity edition', async function (assert) {
         res_id: resPartnerId1,
         res_model: 'res.partner',
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action, options }) => {
+    const { click, createChatterContainerComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('do_action');
             assert.strictEqual(
                 action.context.default_res_id,
@@ -927,9 +930,9 @@ QUnit.test('activity edition', async function (assert) {
                 'Action should have activity id as res_id'
             );
             pyEnv['mail.activity'].write([mailActivityId1], { icon: 'fa-check' });
-            options.on_close();
+            options.onClose();
+        },
     });
-    const { click, createChatterContainerComponent } = await start({ env: { bus } });
     await createChatterContainerComponent({
         threadId: resPartnerId1,
         threadModel: 'res.partner',
@@ -995,9 +998,6 @@ QUnit.test('activity click on cancel', async function (assert) {
                 assert.step('unlink');
                 assert.strictEqual(args.args[0].length, 1);
                 assert.strictEqual(args.args[0][0], mailActivityId1);
-                return;
-            } else {
-                return this._super(...arguments);
             }
         },
     });
@@ -1109,8 +1109,20 @@ QUnit.test('activity mark done popover click on discard', async function (assert
 QUnit.test('data-oe-id & data-oe-model link redirection on click', async function (assert) {
     assert.expect(7);
 
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const pyEnv = await startServer();
+    const resPartnerId1 = pyEnv['res.partner'].create();
+    const emailActivityTypeId = pyEnv['mail.activity.type'].search([['name', '=', 'Email']])[0];
+    pyEnv['mail.activity'].create({
+        activity_category: 'default',
+        activity_type_id: emailActivityTypeId,
+        can_write: true,
+        note: `<p><a href="#" data-oe-id="250" data-oe-model="some.model">some.model_250</a></p>`,
+        res_id: resPartnerId1,
+        res_model: 'res.partner',
+    });
+    const { createChatterContainerComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.strictEqual(
                 action.type,
                 'ir.actions.act_window',
@@ -1127,19 +1139,8 @@ QUnit.test('data-oe-id & data-oe-model link redirection on click', async functio
                 "action should open view on 250"
             );
             assert.step('do-action:openFormView_some.model_250');
+        },
     });
-    const pyEnv = await startServer();
-    const resPartnerId1 = pyEnv['res.partner'].create();
-    const emailActivityTypeId = pyEnv['mail.activity.type'].search([['name', '=', 'Email']])[0];
-    pyEnv['mail.activity'].create({
-        activity_category: 'default',
-        activity_type_id: emailActivityTypeId,
-        can_write: true,
-        note: `<p><a href="#" data-oe-id="250" data-oe-model="some.model">some.model_250</a></p>`,
-        res_id: resPartnerId1,
-        res_model: 'res.partner',
-    });
-    const { createChatterContainerComponent } = await start({ data: this.data, env: { bus } });
     await createChatterContainerComponent({
         threadId: resPartnerId1,
         threadModel: 'res.partner',
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/attachment_list_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/attachment_list_tests.js
index 3fa20c72f99..6cf7bbeaea8 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/attachment_list_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/attachment_list_tests.js
@@ -81,7 +81,6 @@ QUnit.test('simplest layout + editable', async function (assert) {
                     "should fetch image with 200x200 pixels ratio");
                 assert.step('fetch_image');
             }
-            return this._super(...arguments);
         },
     });
     const attachment = messaging.models['Attachment'].create({
@@ -248,9 +247,7 @@ QUnit.test('clicking on the delete attachment button multiple times should do th
         async mockRPC(route, args) {
             if (route === '/mail/attachment/delete') {
                 assert.step('attachment_unlink');
-                return;
             }
-            return this._super(...arguments);
         },
     });
     const attachment = messaging.models['Attachment'].create({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/chat_window_manager_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/chat_window_manager_tests.js
index fc249484b7b..476e27b6f63 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/chat_window_manager_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/chat_window_manager_tests.js
@@ -10,6 +10,7 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
+import { makeFakeLocalizationService } from "@web/../tests/helpers/mock_services";
 import { file, dom } from 'web.test_utils';
 const { createFile, inputFiles } = file;
 const { triggerEvent } = dom;
@@ -231,12 +232,10 @@ QUnit.test('open chat from "new message" chat window should open chat in place o
     const imSearchDef = makeDeferred();
     patchUiSize({ width: 1920 });
     const { click, createMessagingMenuComponent } = await start({
-        async mockRPC(route, args) {
-            const res = await this._super(...arguments);
+        mockRPC(route, args) {
             if (args.method === 'im_search') {
                 imSearchDef.resolve();
             }
-            return res;
         }
     });
     await createMessagingMenuComponent();
@@ -381,12 +380,10 @@ QUnit.test('new message autocomplete should automatically select first result',
     pyEnv['res.users'].create({ partner_id: resPartnerId1 });
     const imSearchDef = makeDeferred();
     const { click, createMessagingMenuComponent } = await start({
-        async mockRPC(route, args) {
-            const res = await this._super(...arguments);
+        mockRPC(route, args) {
             if (args.method === 'im_search') {
                 imSearchDef.resolve();
             }
-            return res;
         },
     });
     await createMessagingMenuComponent();
@@ -509,7 +506,6 @@ QUnit.test('chat window: fold', async function (assert) {
             if (args.method === 'channel_fold') {
                 assert.step(`rpc:${args.method}/${args.kwargs.state}`);
             }
-            return this._super(...arguments);
         },
     });
     await createMessagingMenuComponent();
@@ -561,7 +557,6 @@ QUnit.test('chat window: open / close', async function (assert) {
             if (args.method === 'channel_fold') {
                 assert.step(`rpc:channel_fold/${args.kwargs.state}`);
             }
-            return this._super(...arguments);
         },
     });
     await createMessagingMenuComponent();
@@ -732,7 +727,6 @@ QUnit.test('chat window: close on ESCAPE', async function (assert) {
             if (args.method === 'channel_fold') {
                 assert.step(`rpc:channel_fold/${args.kwargs.state}`);
             }
-            return this._super(...arguments);
         },
     });
     assert.containsOnce(
@@ -2013,7 +2007,6 @@ QUnit.test('chat window does not fetch messages if hidden', async function (asse
                 const { channel_id } = args;
                 assert.step(`rpc:/mail/channel/messages:${channel_id}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -2280,21 +2273,16 @@ QUnit.test('Textual representations of shift previous/next operations are correc
         },
     ]);
     await start({
-        env: {
-            _t: Object.assign((s => s), {
-                database: {
-                    parameters: {
-                        code: "en_US",
-                        date_format: '%m/%d/%Y',
-                        decimal_point: ".",
-                        direction: 'rtl',
-                        grouping: [],
-                        thousands_sep: ",",
-                        time_format: '%H:%M:%S',
-                    },
-                },
+        services: {
+            localization: makeFakeLocalizationService({
+                dateFormat: '%m/%d/%Y',
+                timeFormat: '%H:%M:%S',
+                direction: 'rtl',
+                grouping: [],
+                thousandsSep: ',',
+                decimalPoint: '.',
             }),
-        }
+        },
     });
 
     assert.strictEqual(
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/chatter_suggested_recipient_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/chatter_suggested_recipient_tests.js
index 5840b8cbf50..7dcde918118 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/chatter_suggested_recipient_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/chatter_suggested_recipient_tests.js
@@ -235,7 +235,6 @@ QUnit.test("suggested recipients should not be notified when posting an internal
                     "post data should not contain suggested recipients when posting an internal note"
                 );
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/chatter_topbar_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/chatter_topbar_tests.js
index ef1cb38dd0c..c3682aa0731 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/chatter_topbar_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/chatter_topbar_tests.js
@@ -118,7 +118,6 @@ QUnit.test('attachment loading is delayed', async function (assert) {
             if (route.includes('/mail/thread/data')) {
                 await makeTestPromise(); // simulate long loading
             }
-            return this._super(...arguments);
         }
     });
     await createChatterContainerComponent({
@@ -160,7 +159,6 @@ QUnit.test('attachment counter while loading attachments', async function (asser
             if (route.includes('/mail/thread/data')) {
                 await makeTestPromise(); // simulate long loading
             }
-            return this._super(...arguments);
         }
     });
     await createChatterContainerComponent({
@@ -198,11 +196,9 @@ QUnit.test('attachment counter transition when attachments become loaded)', asyn
     const attachmentPromise = makeTestPromise();
     const { createChatterContainerComponent } = await start({
         async mockRPC(route) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
             if (route.includes('/mail/thread/data')) {
                 await attachmentPromise;
             }
-            return _super();
         },
     });
     await createChatterContainerComponent({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/composer_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/composer_tests.js
index 6f66c5208d2..de68ab2b36e 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/composer_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/composer_tests.js
@@ -11,7 +11,6 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import FormView from 'web.FormView';
 import {
     file,
     makeTestPromise,
@@ -21,32 +20,7 @@ const { createFile, inputFiles } = file;
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
-QUnit.module('composer_tests.js', {
-    beforeEach() {
-        // FIXME archs could be removed once task-2248306 is done
-        // The mockServer will try to get the list view
-        // of every relational fields present in the main view.
-        // In the case of mail fields, we don't really need them,
-        // but they still need to be defined.
-        this.createView = async (viewParams, ...args) => {
-            const startResult = makeTestPromise();
-            await afterNextRender(async () => {
-                const viewArgs = Object.assign(
-                    {
-                        archs: {
-                            'mail.activity,false,list': '<tree/>',
-                            'mail.followers,false,list': '<tree/>',
-                            'mail.message,false,list': '<tree/>',
-                        },
-                    },
-                    viewParams,
-                );
-                startResult.resolve(await start(viewArgs, ...args));
-            });
-            return startResult;
-        };
-    },
-});
+QUnit.module('composer_tests.js');
 
 QUnit.test('composer text input: basic rendering when posting a message', async function (assert) {
     assert.expect(5);
@@ -613,7 +587,6 @@ QUnit.test('do not send typing notification on typing "/" command', async functi
             if (args.method === 'notify_typing') {
                 assert.step(`notify_typing:${args.kwargs.is_typing}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -637,7 +610,6 @@ QUnit.test('do not send typing notification on typing after selecting suggestion
             if (args.method === 'notify_typing') {
                 assert.step(`notify_typing:${args.kwargs.is_typing}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -1050,7 +1022,6 @@ QUnit.test('composer text input cleared on message post', async function (assert
             if (route === '/mail/message/post') {
                 assert.step('message_post');
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1122,7 +1093,6 @@ QUnit.test('current partner notify is typing to other thread members', async fun
             if (args.method === 'notify_typing') {
                 assert.step(`notify_typing:${args.kwargs.is_typing}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -1152,7 +1122,6 @@ QUnit.test('current partner is typing should not translate on textual typing sta
             if (args.method === 'notify_typing') {
                 assert.step(`notify_typing:${args.kwargs.is_typing}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -1190,7 +1159,6 @@ QUnit.test('current partner notify no longer is typing to thread members after 5
             if (args.method === 'notify_typing') {
                 assert.step(`notify_typing:${args.kwargs.is_typing}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -1227,7 +1195,6 @@ QUnit.test('current partner notify is typing again to other members every 50s of
             if (args.method === 'notify_typing') {
                 assert.step(`notify_typing:${args.kwargs.is_typing}`);
             }
-            return this._super(...arguments);
         },
     });
 
@@ -1259,12 +1226,10 @@ QUnit.test('composer: send button is disabled if attachment upload is not finish
     const attachmentUploadedPromise = makeTestPromise();
     const mailChannelId1 = pyEnv['mail.channel'].create();
     const { createComposerComponent, messaging } = await start({
-        async mockFetch(resource, init) {
-            const res = this._super(...arguments);
-            if (resource === '/mail/attachment/upload') {
+        async mockRPC(route) {
+            if (route === '/mail/attachment/upload') {
                 await attachmentUploadedPromise;
             }
-            return res;
         }
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1373,13 +1338,11 @@ QUnit.test('remove an uploading attachment', async function (assert) {
     const pyEnv = await startServer();
     const mailChannelId1 = pyEnv['mail.channel'].create();
     const { click, createComposerComponent, messaging } = await start({
-        async mockFetch(resource, init) {
-            const res = this._super(...arguments);
-            if (resource === '/mail/attachment/upload') {
+        async mockRPC(route) {
+            if (route === '/mail/attachment/upload') {
                 // simulates uploading indefinitely
                 await new Promise(() => {});
             }
-            return res;
         }
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1428,13 +1391,11 @@ QUnit.test('remove an uploading attachment aborts upload', async function (asser
     const pyEnv = await startServer();
     const mailChannelId1 = pyEnv['mail.channel'].create();
     const { afterEvent, createComposerComponent, messaging } = await start({
-        async mockFetch(resource, init) {
-            const res = this._super(...arguments);
-            if (resource === '/mail/attachment/upload') {
+        async mockRPC(route) {
+            if (route === '/mail/attachment/upload') {
                 // simulates uploading indefinitely
                 await new Promise(() => {});
             }
-            return res;
         }
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1477,13 +1438,9 @@ QUnit.test("Show a default status in the recipient status text when the thread d
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create();
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -1491,9 +1448,15 @@ QUnit.test("Show a default status in the recipient status text when the thread d
                     <field name="message_follower_ids"/>
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { click, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     await click('.o_ChatterTopbar_buttonSendMessage');
     assert.strictEqual(
@@ -1508,13 +1471,9 @@ QUnit.test("Show a thread name in the recipient status text.", async function (a
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create({ name: "test name" });
-    const { click, messaging } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -1522,9 +1481,15 @@ QUnit.test("Show a thread name in the recipient status text.", async function (a
                     <field name="message_follower_ids"/>
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { click, messaging, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     // hack: provide awareness of name (not received in usual chatter flow)
     messaging.models['Thread'].insert({ id: resPartnerId1, model: 'res.partner', name: "test name" });
@@ -1546,7 +1511,6 @@ QUnit.test('send message only once when button send is clicked twice quickly', a
             if (route === '/mail/message/post') {
                 assert.step('message_post');
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1578,12 +1542,10 @@ QUnit.test('[technical] does not crash when an attachment is removed before its
     const uploadPromise = makeTestPromise();
     const mailChannelId1 = pyEnv['mail.channel'].create();
     const { createComposerComponent, messaging } = await start({
-        async mockFetch(resource) {
-            const _super = this._super.bind(this, ...arguments);
-            if (resource === '/mail/attachment/upload') {
+        async mockRPC(route) {
+            if (route === '/mail/attachment/upload') {
                 await uploadPromise;
             }
-            return _super();
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/discuss_inbox_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/discuss_inbox_tests.js
index 58798fb52d1..289dabb8390 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/discuss_inbox_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/discuss_inbox_tests.js
@@ -7,7 +7,7 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -348,7 +348,6 @@ QUnit.test('"reply to" composer should log note if message replied to is a note'
                     "should set subtype_xmlid as 'note'"
                 );
             }
-            return this._super(...arguments);
         },
         waitUntilEvent: {
             eventName: 'o-thread-view-hint-processed',
@@ -415,7 +414,6 @@ QUnit.test('"reply to" composer should send message if message replied to is not
                     "should set subtype_xmlid as 'comment'"
                 );
             }
-            return this._super(...arguments);
         },
         waitUntilEvent: {
             eventName: 'o-thread-view-hint-processed',
@@ -601,8 +599,21 @@ QUnit.test('click on (non-channel/non-partner) origin thread link should redirec
         notification_type: 'inbox',
         res_partner_id: pyEnv.currentPartnerId,
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { env } = await this.start({
+        waitUntilEvent: {
+            eventName: 'o-thread-view-hint-processed',
+            message: "should wait until inbox displayed its messages",
+            predicate: ({ hint, threadViewer }) => {
+                return (
+                    hint.type === 'messages-loaded' &&
+                    threadViewer.thread.model === 'mail.box' &&
+                    threadViewer.thread.id === 'inbox'
+                );
+            },
+        },
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             // Callback of doing an action (action manager).
             // Expected to be called on click on origin thread link,
             // which redirects to form view of record related to origin thread
@@ -627,21 +638,7 @@ QUnit.test('click on (non-channel/non-partner) origin thread link should redirec
                 resFakeId1,
                 "action should open view with id of resFake1 (id of message origin thread)"
             );
-    });
-    await this.start({
-        env: {
-            bus,
-        },
-        waitUntilEvent: {
-            eventName: 'o-thread-view-hint-processed',
-            message: "should wait until inbox displayed its messages",
-            predicate: ({ hint, threadViewer }) => {
-                return (
-                    hint.type === 'messages-loaded' &&
-                    threadViewer.thread.model === 'mail.box' &&
-                    threadViewer.thread.id === 'inbox'
-                );
-            },
+            return Promise.resolve();
         },
     });
     assert.containsOnce(
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/discuss_pinned_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/discuss_pinned_tests.js
index f1d66f75f9e..f807539a895 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/discuss_pinned_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/discuss_pinned_tests.js
@@ -78,7 +78,6 @@ QUnit.test('sidebar: pinned channel 3: open channel and leave it', async functio
                     "The right id is sent to the server to remove"
                 );
             }
-            return this._super(...arguments);
         },
     });
 
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/discuss_sidebar_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/discuss_sidebar_tests.js
index 878daa9cc31..d96ebc02aab 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/discuss_sidebar_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/discuss_sidebar_tests.js
@@ -25,11 +25,9 @@ QUnit.test('sidebar find shows channels matching search term', async function (a
     const { click } = await start({
         autoOpenDiscuss: true,
         async mockRPC(route, args) {
-            const res = await this._super(...arguments);
             if (args.method === 'search_read') {
                 searchReadDef.resolve();
             }
-            return res;
         },
     });
     await click(`.o_DiscussSidebarCategory_commandAdd`);
@@ -78,11 +76,9 @@ QUnit.test('sidebar find shows channels matching search term even when user is m
     const { click } = await start({
         autoOpenDiscuss: true,
         async mockRPC(route, args) {
-            const res = await this._super(...arguments);
             if (args.method === 'search_read') {
                 searchReadDef.resolve();
             }
-            return res;
         },
     });
     await click(`.o_DiscussSidebarCategory_commandAdd`);
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/discuss_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/discuss_tests.js
index dfdcbd8f0bd..4de8ade642f 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/discuss_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/discuss_tests.js
@@ -10,7 +10,9 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { makeFakeNotificationService } from "@web/../tests/helpers/mock_services";
+import { destroy } from '@web/../tests/helpers/utils';
+
 import { makeTestPromise, file } from 'web.test_utils';
 
 const { createFile, inputFiles } = file;
@@ -59,9 +61,9 @@ QUnit.test('discuss should be marked as opened if the component is already rende
 QUnit.test('discuss should be marked as closed when the component is unmounted', async function (assert) {
     assert.expect(1);
 
-    const { messaging, widget } = await this.start();
+    const { messaging, webClient } = await this.start();
 
-    await afterNextRender(() => widget.destroy());
+    await afterNextRender(() => destroy(webClient));
     assert.notOk(
         messaging.discuss.discussView,
         "discuss should be marked as closed when the component is unmounted"
@@ -73,11 +75,9 @@ QUnit.test('messaging not initialized', async function (assert) {
 
     await this.start({
         async mockRPC(route) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
             if (route === '/mail/init_messaging') {
                 await makeTestPromise(); // simulate messaging never initialized
             }
-            return _super();
         },
         waitUntilMessagingCondition: 'created',
     });
@@ -95,11 +95,9 @@ QUnit.test('messaging becomes initialized', async function (assert) {
 
     await this.start({
         async mockRPC(route) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
             if (route === '/mail/init_messaging') {
                 await messagingInitializedProm;
             }
-            return _super();
         },
         waitUntilMessagingCondition: 'created',
     });
@@ -1022,7 +1020,6 @@ QUnit.test('initially load messages from inbox', async function (assert) {
                     "should fetch up to 30 messages"
                 );
             }
-            return this._super(...arguments);
         },
     });
     assert.verifySteps(['/mail/channel/messages']);
@@ -1093,7 +1090,6 @@ QUnit.test('load single message from channel initially', async function (assert)
                     "should fetch up to 30 messages"
                 );
             }
-            return this._super(...arguments);
         },
     });
     assert.strictEqual(
@@ -1506,7 +1502,6 @@ QUnit.test('load all messages from channel initially, less than fetch limit (29
             if (route === '/mail/channel/messages') {
                 assert.strictEqual(args.limit, 30, "should fetch up to 30 messages");
             }
-            return this._super(...arguments);
         },
     });
     assert.strictEqual(
@@ -2442,7 +2437,6 @@ QUnit.test('toggle_star message', async function (assert) {
                     "should have message Id in args"
                 );
             }
-            return this._super(...arguments);
         },
     });
     assert.strictEqual(
@@ -2654,7 +2648,6 @@ QUnit.test('post a simple message', async function (assert) {
 
     const pyEnv = await startServer();
     const mailChannelId1 = pyEnv['mail.channel'].create();
-    let postedMessageId;
     const { click, insertText, messaging } = await this.start({
         discuss: {
             params: {
@@ -2662,7 +2655,6 @@ QUnit.test('post a simple message', async function (assert) {
             },
         },
         async mockRPC(route, args) {
-            const res = await this._super(...arguments);
             if (route === '/mail/message/post') {
                 assert.step('message_post');
                 assert.strictEqual(
@@ -2690,9 +2682,7 @@ QUnit.test('post a simple message', async function (assert) {
                     "mail.mt_comment",
                     "should set subtype_xmlid as 'comment'"
                 );
-                postedMessageId = res.id;
             }
-            return res;
         },
     });
     assert.strictEqual(
@@ -2731,6 +2721,7 @@ QUnit.test('post a simple message', async function (assert) {
         1,
         "should display a message after posting message"
     );
+    const [postedMessageId] = pyEnv['mail.message'].search([], { order: 'id DESC' });
     const message = document.querySelector(`.o_Message`);
     assert.strictEqual(
         message.dataset.messageLocalId,
@@ -3127,22 +3118,19 @@ QUnit.test('reply to message from inbox (message linked to document)', async fun
                     "should set message type as 'comment'"
                 );
             }
-            return this._super(...arguments);
         },
         services: {
-            notification: {
-                notify(notification) {
-                    assert.ok(
-                        true,
-                        "should display a notification after posting reply"
-                    );
-                    assert.strictEqual(
-                        notification.message,
-                        "Message posted on \"Refactoring\"",
-                        "notification should tell that message has been posted to the record 'Refactoring'"
-                    );
-                }
-            }
+            notification: makeFakeNotificationService(notification => {
+                assert.ok(
+                    true,
+                    "should display a notification after posting reply"
+                );
+                assert.strictEqual(
+                    notification,
+                    "Message posted on \"Refactoring\"",
+                    "notification should tell that message has been posted to the record 'Refactoring'"
+                );
+            }),
         },
     });
     assert.strictEqual(
@@ -3531,15 +3519,8 @@ QUnit.test('receive new chat message: out of odoo focus (notification, channel)'
 
     const pyEnv = await startServer();
     const mailChannelId1 = pyEnv['mail.channel'].create({ channel_type: 'chat' });
-    const bus = new Bus();
-    bus.on('set_title_part', null, payload => {
-        assert.step('set_title_part');
-        assert.strictEqual(payload.part, '_chat');
-        assert.strictEqual(payload.title, "1 Message");
-    });
-    await this.start({
-        env: { bus },
-        services: {
+    const { env } = await this.start({
+        legacyServices: {
             bus_service: BusService.extend({
                 _beep() {}, // Do nothing
                 _poll() {}, // Do nothing
@@ -3549,6 +3530,11 @@ QUnit.test('receive new chat message: out of odoo focus (notification, channel)'
             }),
         },
     });
+    env.bus.on('set_title_part', null, payload => {
+        assert.step('set_title_part');
+        assert.strictEqual(payload.part, '_chat');
+        assert.strictEqual(payload.title, "1 Message");
+    });
 
     const mailChannel1 = pyEnv['mail.channel'].searchRead([['id', '=', mailChannelId1]])[0];
     // simulate receiving a new message with odoo focused
@@ -3570,15 +3556,8 @@ QUnit.test('receive new chat message: out of odoo focus (notification, chat)', a
 
     const pyEnv = await startServer();
     const mailChannelId1 = pyEnv['mail.channel'].create({ channel_type: "chat" });
-    const bus = new Bus();
-    bus.on('set_title_part', null, payload => {
-        assert.step('set_title_part');
-        assert.strictEqual(payload.part, '_chat');
-        assert.strictEqual(payload.title, "1 Message");
-    });
-    await this.start({
-        env: { bus },
-        services: {
+    const { env } = await this.start({
+        legacyServices: {
             bus_service: BusService.extend({
                 _beep() {}, // Do nothing
                 _poll() {}, // Do nothing
@@ -3588,6 +3567,11 @@ QUnit.test('receive new chat message: out of odoo focus (notification, chat)', a
             }),
         },
     });
+    env.bus.on('set_title_part', null, payload => {
+        assert.step('set_title_part');
+        assert.strictEqual(payload.part, '_chat');
+        assert.strictEqual(payload.title, "1 Message");
+    });
 
     const mailChannel1 = pyEnv['mail.channel'].searchRead([['id', '=', mailChannelId1]])[0];
     // simulate receiving a new message with odoo focused
@@ -3613,8 +3597,18 @@ QUnit.test('receive new chat messages: out of odoo focus (tab title)', async fun
         { channel_type: 'chat', public: 'private' },
         { channel_type: 'chat', public: 'private' },
     ]);
-    const bus = new Bus();
-    bus.on('set_title_part', null, payload => {
+    const { env } = await this.start({
+        legacyServices: {
+            bus_service: BusService.extend({
+                _beep() {}, // Do nothing
+                _poll() {}, // Do nothing
+                _registerWindowUnload() {}, // Do nothing
+                isOdooFocused: () => false,
+                updateOption() {},
+            }),
+        },
+    });
+    env.bus.on('set_title_part', null, payload => {
         step++;
         assert.step('set_title_part');
         assert.strictEqual(payload.part, '_chat');
@@ -3628,18 +3622,6 @@ QUnit.test('receive new chat messages: out of odoo focus (tab title)', async fun
             assert.strictEqual(payload.title, "3 Messages");
         }
     });
-    await this.start({
-        env: { bus },
-        services: {
-            bus_service: BusService.extend({
-                _beep() {}, // Do nothing
-                _poll() {}, // Do nothing
-                _registerWindowUnload() {}, // Do nothing
-                isOdooFocused: () => false,
-                updateOption() {},
-            }),
-        },
-    });
 
     const mailChannel1 = pyEnv['mail.channel'].searchRead([['id', '=', mailChannelId1]])[0];
     // simulate receiving a new message in chat 1 with odoo focused
@@ -3885,30 +3867,26 @@ QUnit.test('warning on send with shortcut when attempting to post message with s
                 active_id: `mail.channel_${mailChannelId1}`,
             },
         },
-        async mockFetch(resource, init) {
-            const res = this._super(...arguments);
-            if (resource === '/mail/attachment/upload') {
+        async mockRPC(route) {
+            if (route === '/mail/attachment/upload') {
                 // simulates attachment is never finished uploading
                 await new Promise(() => {});
             }
-            return res;
         },
         services: {
-            notification: {
-                notify(params) {
-                    assert.strictEqual(
-                        params.message,
-                        "Please wait while the file is uploading.",
-                        "notification content should be about the uploading file"
-                    );
-                    assert.strictEqual(
-                        params.type,
-                        'warning',
-                        "notification should be a warning"
-                    );
-                    assert.step('notification');
-                }
-            }
+            notification: makeFakeNotificationService((message, options) => {
+                assert.strictEqual(
+                    message,
+                    "Please wait while the file is uploading.",
+                    "notification content should be about the uploading file"
+                );
+                assert.strictEqual(
+                    options.type,
+                    'warning',
+                    "notification should be a warning"
+                );
+                assert.step('notification');
+            }),
         },
     });
     const file = await createFile({
@@ -3963,7 +3941,6 @@ QUnit.test('send message only once when enter is pressed twice quickly', async f
             if (route === '/mail/message/post') {
                 assert.step('message_post');
             }
-            return this._super(...arguments);
         },
     });
     // Type message
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/follow_button_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/follow_button_tests.js
index bbd2ddbb6ee..df459d8b544 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/follow_button_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/follow_button_tests.js
@@ -1,54 +1,21 @@
 /** @odoo-module **/
 
-import { makeDeferred } from '@mail/utils/deferred';
 import {
     afterNextRender,
     start,
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import FormView from 'web.FormView';
-
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
-QUnit.module('follow_button_tests.js', {
-    beforeEach() {
-        // FIXME archs could be removed once task-2248306 is done
-        // The mockServer will try to get the list view
-        // of every relational fields present in the main view.
-        // In the case of mail fields, we don't really need them,
-        // but they still need to be defined.
-        this.createView = async (viewParams, ...args) => {
-            const startResult = makeDeferred();
-            await afterNextRender(async () => {
-                const viewArgs = Object.assign(
-                    {
-                        archs: {
-                            'mail.activity,false,list': '<tree/>',
-                            'mail.followers,false,list': '<tree/>',
-                            'mail.message,false,list': '<tree/>',
-                        },
-                    },
-                    viewParams,
-                );
-                startResult.resolve(await start(viewArgs, ...args));
-            });
-            return startResult;
-        };
-    },
-});
+QUnit.module('follow_button_tests.js');
 
 QUnit.test('base rendering not editable', async function (assert) {
     assert.expect(2);
 
-    const pyEnv = await startServer();
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -56,9 +23,15 @@ QUnit.test('base rendering not editable', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView, pyEnv } = await start({
+        serverData: { views },
+    });
+    await openView({
         res_id: pyEnv.currentPartnerId,
+        res_model: 'res.partner',
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -86,13 +59,9 @@ QUnit.test('hover following button', async function (assert) {
     pyEnv['res.partner'].write([pyEnv.currentPartnerId], {
         message_follower_ids: [followerId],
     });
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -100,9 +69,15 @@ QUnit.test('hover following button', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
         res_id: pyEnv.currentPartnerId,
+        res_model: 'res.partner',
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -156,14 +131,9 @@ QUnit.test('hover following button', async function (assert) {
 QUnit.test('click on "follow" button', async function (assert) {
     assert.expect(6);
 
-    const pyEnv = await startServer();
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -171,15 +141,20 @@ QUnit.test('click on "follow" button', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
-        res_id: pyEnv.currentPartnerId,
+            </form>`,
+    };
+    const { click, openView, pyEnv } = await start({
         async mockRPC(route, args) {
             if (route.includes('message_subscribe')) {
                 assert.step('rpc:message_subscribe');
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_id: pyEnv.currentPartnerId,
+        res_model: 'res.partner',
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -222,13 +197,9 @@ QUnit.test('click on "unfollow" button', async function (assert) {
     pyEnv['res.partner'].write([pyEnv.currentPartnerId], {
         message_follower_ids: [followerId],
     });
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -236,15 +207,20 @@ QUnit.test('click on "unfollow" button', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
-        res_id: pyEnv.currentPartnerId,
+            </form>`,
+    };
+    const { click, openView } = await start({
         async mockRPC(route, args) {
             if (route.includes('message_unsubscribe')) {
                 assert.step('rpc:message_unsubscribe');
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_id: pyEnv.currentPartnerId,
+        res_model: 'res.partner',
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/follower_list_menu_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/follower_list_menu_tests.js
index ce22535382d..76c428414f4 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/follower_list_menu_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/follower_list_menu_tests.js
@@ -1,55 +1,23 @@
 /** @odoo-module **/
 
-import { makeDeferred } from '@mail/utils/deferred';
 import {
-    afterNextRender,
     start,
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
 import { nextTick } from 'web.test_utils';
-import FormView from 'web.FormView';
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
-QUnit.module('follower_list_menu_tests.js', {
-    async beforeEach() {
-        // FIXME archs could be removed once task-2248306 is done
-        // The mockServer will try to get the list view
-        // of every relational fields present in the main view.
-        // In the case of mail fields, we don't really need them,
-        // but they still need to be defined.
-        this.createView = async (viewParams, ...args) => {
-            const startResult = makeDeferred();
-            await afterNextRender(async () => {
-                const viewArgs = Object.assign(
-                    {
-                        archs: {
-                            'mail.activity,false,list': '<tree/>',
-                            'mail.followers,false,list': '<tree/>',
-                            'mail.message,false,list': '<tree/>',
-                        },
-                    },
-                    viewParams,
-                );
-                startResult.resolve(await start(viewArgs, ...args));
-            });
-            return startResult;
-        };
-    },
-});
+QUnit.module('follower_list_menu_tests.js');
 
 QUnit.test('base rendering not editable', async function (assert) {
     assert.expect(5);
 
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -57,12 +25,18 @@ QUnit.test('base rendering not editable', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
-        viewOptions: {
-            mode: 'edit',
-        },
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
     });
+    await openView(
+        {
+            res_model: 'res.partner',
+            views: [[false, 'form']],
+        },
+        { mode: 'edit' },
+    );
     assert.containsOnce(
         document.body,
         '.o_FollowerListMenu',
@@ -99,14 +73,13 @@ QUnit.test('base rendering editable', async function (assert) {
     const resPartnerId1 = pyEnv['res.partner'].create();
 
     const { click, createChatterContainerComponent } = await start({
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(route, args);
                 res['hasWriteAccess'] = true;
                 return res;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -159,8 +132,19 @@ QUnit.test('click on "add followers" button', async function (assert) {
         res_id: resPartnerId1,
         res_model: 'res.partner',
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action, options }) => {
+
+    const { click, createChatterContainerComponent, env } = await start({
+        async mockRPC(route, args, performRPC) {
+            if (route === '/mail/thread/data') {
+                // mimic user with write access
+                const res = await performRPC(route, args);
+                res['hasWriteAccess'] = true;
+                return res;
+            }
+        },
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('action:open_view');
             assert.strictEqual(
                 action.context.default_res_model,
@@ -190,19 +174,7 @@ QUnit.test('click on "add followers" button', async function (assert) {
                 res_id: resPartnerId1,
                 res_model: 'res.partner',
             });
-            options.on_close();
-    });
-
-    const { click, createChatterContainerComponent } = await start({
-        env: { bus },
-        async mockRPC(route, args) {
-            if (route === '/mail/thread/data') {
-                // mimic user with write access
-                const res = await this._super(...arguments);
-                res['hasWriteAccess'] = true;
-                return res;
-            }
-            return this._super(...arguments);
+            options.onClose();
         },
     });
     await createChatterContainerComponent({
@@ -284,10 +256,10 @@ QUnit.test('click on remove follower', async function (assert) {
         res_model: 'res.partner',
     });
     const { click, createChatterContainerComponent } = await start({
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(route, args);
                 res['hasWriteAccess'] = true;
                 return res;
             }
@@ -299,7 +271,6 @@ QUnit.test('click on remove follower', async function (assert) {
                     "message_unsubscribe should be called with right argument"
                 );
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -353,14 +324,13 @@ QUnit.test('Hide "Add follower" and subtypes edition/removal buttons except own
         },
     ]);
     const { click, createChatterContainerComponent } = await start({
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with no write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(route, args);
                 res['hasWriteAccess'] = false;
                 return res;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -419,14 +389,13 @@ QUnit.test('Show "Add follower" and subtypes edition/removal buttons on all foll
         },
     ]);
     const { click, createChatterContainerComponent } = await start({
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(...arguments);
                 res['hasWriteAccess'] = true;
                 return res;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -470,14 +439,13 @@ QUnit.test('Show "No Followers" dropdown-item if there are no followers and user
 
     const resPartnerId1 = pyEnv['res.partner'].create();
     const { click, createChatterContainerComponent } = await start({
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user without write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(route, args);
                 res['hasWriteAccess'] = false;
                 return res;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/follower_subtype_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/follower_subtype_tests.js
index e067d671505..3c996a17962 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/follower_subtype_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/follower_subtype_tests.js
@@ -1,42 +1,13 @@
 /** @odoo-module **/
 
-import { makeDeferred } from '@mail/utils/deferred';
 import {
-    afterNextRender,
     start,
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import FormView from 'web.FormView';
-
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
-QUnit.module('follower_subtype_tests.js', {
-    beforeEach() {
-        // FIXME archs could be removed once task-2248306 is done
-        // The mockServer will try to get the list view
-        // of every relational fields present in the main view.
-        // In the case of mail fields, we don't really need them,
-        // but they still need to be defined.
-        this.createView = async (viewParams, ...args) => {
-            const startResult = makeDeferred();
-            await afterNextRender(async () => {
-                const viewArgs = Object.assign(
-                    {
-                        archs: {
-                            'mail.activity,false,list': '<tree/>',
-                            'mail.followers,false,list': '<tree/>',
-                            'mail.message,false,list': '<tree/>',
-                        },
-                    },
-                    viewParams,
-                );
-                startResult.resolve(await start(viewArgs, ...args));
-            });
-            return startResult;
-        };
-    },
-});
+QUnit.module('follower_subtype_tests.js');
 
 QUnit.test('simplest layout of a followed subtype', async function (assert) {
     assert.expect(5);
@@ -56,13 +27,9 @@ QUnit.test('simplest layout of a followed subtype', async function (assert) {
     pyEnv['res.partner'].write([pyEnv.currentPartnerId], {
         message_follower_ids: [followerId],
     });
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -70,19 +37,24 @@ QUnit.test('simplest layout of a followed subtype', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
-        res_id: pyEnv.currentPartnerId,
+            </form>`,
+    };
+    const { click, openView } = await start({
         // FIXME: should adapt mock server code to provide `hasWriteAccess`
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(...arguments);
                 res['hasWriteAccess'] = true;
                 return res;
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
+        res_id: pyEnv.currentPartnerId,
+        views: [[false, 'form']],
     });
     await click('.o_FollowerListMenu_buttonFollowers');
     await click('.o_Follower_editButton');
@@ -129,13 +101,9 @@ QUnit.test('simplest layout of a not followed subtype', async function (assert)
     pyEnv['res.partner'].write([pyEnv.currentPartnerId], {
         message_follower_ids: [followerId],
     });
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -143,19 +111,24 @@ QUnit.test('simplest layout of a not followed subtype', async function (assert)
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
-        res_id: pyEnv.currentPartnerId,
+            </form>`,
+    };
+    const { click, openView } = await start({
         // FIXME: should adapt mock server code to provide `hasWriteAccess`
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(...arguments);
                 res['hasWriteAccess'] = true;
                 return res;
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
+        res_id: pyEnv.currentPartnerId,
+        views: [[false, 'form']],
     });
     await click('.o_FollowerListMenu_buttonFollowers');
     await click('.o_Follower_editButton');
@@ -182,13 +155,9 @@ QUnit.test('toggle follower subtype checkbox', async function (assert) {
     pyEnv['res.partner'].write([pyEnv.currentPartnerId], {
         message_follower_ids: [followerId],
     });
-    const { click, messaging } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -196,19 +165,24 @@ QUnit.test('toggle follower subtype checkbox', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
-        res_id: pyEnv.currentPartnerId,
+            </form>`,
+    };
+    const { click, messaging, openView } = await start({
         // FIXME: should adapt mock server code to provide `hasWriteAccess`
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRPC) {
             if (route === '/mail/thread/data') {
                 // mimic user with write access
-                const res = await this._super(...arguments);
+                const res = await performRPC(...arguments);
                 res['hasWriteAccess'] = true;
                 return res;
             }
-            return this._super(...arguments);
         },
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
+        res_id: pyEnv.currentPartnerId,
+        views: [[false, 'form']],
     });
     await click('.o_FollowerListMenu_buttonFollowers');
     await click('.o_Follower_editButton');
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/follower_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/follower_tests.js
index a5828178ee7..b2d0bdb828b 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/follower_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/follower_tests.js
@@ -3,7 +3,7 @@
 import { makeDeferred } from '@mail/utils/deferred';
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -21,14 +21,13 @@ QUnit.test('base rendering not editable', async function (assert) {
         res_model: 'res.partner',
     });
     const { click, createChatterContainerComponent } = await start({
-        async mockRPC(route, args) {
+        async mockRPC(route, args, performRpc) {
             if (route === '/mail/thread/data') {
                 // mimic user without write access
-                const res = await this._super(...arguments);
+                const res = await performRpc(...arguments);
                 res['hasWriteAccess'] = false;
                 return res;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -124,8 +123,13 @@ QUnit.test('click on partner follower details', async function (assert) {
         res_model: 'res.partner',
     });
     const openFormDef = makeDeferred();
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { click, createChatterContainerComponent, env } = await start();
+    await createChatterContainerComponent({
+        threadId,
+        threadModel: 'res.partner',
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.res_id,
@@ -143,11 +147,7 @@ QUnit.test('click on partner follower details', async function (assert) {
                 "The redirect action should be of type 'ir.actions.act_window'"
             );
             openFormDef.resolve();
-    });
-    const { click, createChatterContainerComponent } = await start({ env: { bus } });
-    await createChatterContainerComponent({
-        threadId,
-        threadModel: 'res.partner',
+        },
     });
     await click('.o_FollowerListMenu_buttonFollowers');
     assert.containsOnce(
@@ -185,7 +185,6 @@ QUnit.test('click on edit follower', async function (assert) {
             if (route.includes('/mail/read_subscription_data')) {
                 assert.step('fetch_subtypes');
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].create({
@@ -245,7 +244,6 @@ QUnit.test('edit follower and close subtype dialog', async function (assert) {
                     res_model: 'res.partner'
                 }];
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/message_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/message_tests.js
index f3c7c1333c7..86439f030ff 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/message_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/message_tests.js
@@ -9,7 +9,7 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -188,8 +188,9 @@ QUnit.test('Notification Error', async function (assert) {
         res_partner_id: resPartnerId1,
     });
     const openResendActionDef = makeDeferred();
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action, options }) => {
+    const { createThreadViewComponent, env, messaging } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('do_action');
             assert.strictEqual(
                 action,
@@ -202,8 +203,8 @@ QUnit.test('Notification Error', async function (assert) {
                 "action should have correct message id"
             );
             openResendActionDef.resolve();
+        },
     });
-    const { createThreadViewComponent, messaging } = await start({ env: { bus } });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
         id: mailChannelId1,
         model: 'mail.channel',
@@ -744,8 +745,9 @@ QUnit.test('subtype description should not be displayed if it is similar to body
 QUnit.test('data-oe-id & data-oe-model link redirection on click', async function (assert) {
     assert.expect(7);
 
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { createMessageComponent, env, messaging } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.strictEqual(
                 action.type,
                 'ir.actions.act_window',
@@ -762,8 +764,8 @@ QUnit.test('data-oe-id & data-oe-model link redirection on click', async functio
                 "action should open view on 250"
             );
             assert.step('do-action:openFormView_some.model_250');
+        },
     });
-    const { createMessageComponent, messaging } = await start({ env: { bus } });
     const message = messaging.models['Message'].create({
         body: `<p><a href="#" data-oe-id="250" data-oe-model="some.model">some.model_250</a></p>`,
         id: 100,
@@ -961,7 +963,11 @@ QUnit.test('message should not be considered as "clicked" after clicking on noti
         notification_status: 'exception',
         notification_type: 'email',
     });
-    const { createThreadViewComponent, messaging } = await start();
+    const { createThreadViewComponent, env, messaging } = await start();
+    patchWithCleanup(env.services.action, {
+        // intercept the action: this action is not relevant in the context of this test.
+        doAction() {},
+    });
     const threadViewer = messaging.models['ThreadViewer'].create({
         hasThreadView: true,
         qunitTest: insertAndReplace(),
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/messaging_menu_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/messaging_menu_tests.js
index 788a72075f2..5cf90e078ea 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/messaging_menu_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/messaging_menu_tests.js
@@ -7,7 +7,8 @@ import {
 } from '@mail/../tests/helpers/test_utils';
 
 import { browser } from '@web/core/browser/browser';
-import { patchWithCleanup } from '@web/../tests/helpers/utils';
+import { makeFakeNotificationService } from "@web/../tests/helpers/mock_services";
+import { patchWithCleanup } from "@web/../tests/helpers/utils";
 
 import { makeTestPromise } from 'web.test_utils';
 
@@ -56,7 +57,6 @@ QUnit.test('messaging not initialized', async function (assert) {
                 // simulate messaging never initialized
                 return new Promise(resolve => {});
             }
-            return this._super(...arguments);
         },
         waitUntilMessagingCondition: 'created',
     });
@@ -82,11 +82,9 @@ QUnit.test('messaging becomes initialized', async function (assert) {
 
     const { click, createMessagingMenuComponent } = await start({
         async mockRPC(route) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
             if (route === '/mail/init_messaging') {
                 await messagingInitializedProm;
             }
-            return _super();
         },
         waitUntilMessagingCondition: 'created',
     });
@@ -403,7 +401,7 @@ QUnit.test('new message', async function (assert) {
 QUnit.test('no new message when discuss is open', async function (assert) {
     assert.expect(3);
 
-    const { click, discussWidget, createMessagingMenuComponent } = await start({
+    const { click, createMessagingMenuComponent, openDiscuss, openView } = await start({
         autoOpenDiscuss: true,
     });
     await createMessagingMenuComponent();
@@ -415,16 +413,18 @@ QUnit.test('no new message when discuss is open', async function (assert) {
         "should not have 'new message' when discuss is open"
     );
 
-    // simulate closing discuss app
-    await afterNextRender(() => discussWidget.on_detach_callback());
+    await openView({
+        res_model: 'res.partner',
+        views: [[false, 'form']],
+    });
+
     assert.strictEqual(
         document.querySelectorAll(`.o_MessagingMenu_newMessageButton`).length,
         1,
         "should have 'new message' when discuss is closed"
     );
 
-    // simulate opening discuss app
-    await afterNextRender(() => discussWidget.on_attach_callback());
+    await openDiscuss();
     assert.strictEqual(
         document.querySelectorAll(`.o_MessagingMenu_newMessageButton`).length,
         0,
@@ -916,16 +916,12 @@ QUnit.test('respond to notification prompt (denied)', async function (assert) {
         },
     });
     const { click, createMessagingMenuComponent } = await start({
-        env: {
-            services: {
-                notification: {
-                    notify() {
-                        assert.step(
-                            "should display a toast notification with the deny confirmation"
-                        );
-                    }
-                }
-            }
+        services: {
+            notification: makeFakeNotificationService(() => {
+                assert.step(
+                    "should display a toast notification with the deny confirmation"
+                );
+            }),
         },
     });
     await createMessagingMenuComponent();
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
index 286cd7eae7b..6d29043052d 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
@@ -2,7 +2,7 @@
 
 import { afterNextRender, start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -225,8 +225,10 @@ QUnit.test('grouped notifications by document model', async function (assert) {
             notification_type: 'email', // expected failure type for email message
         },
     ]);
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+
+    const { createNotificationListComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.name,
@@ -263,9 +265,8 @@ QUnit.test('grouped notifications by document model', async function (assert) {
                 JSON.stringify([['message_has_error', '=', true]]),
                 "action should have 'message_has_error' as domain"
             );
+        },
     });
-
-    const { createNotificationListComponent } = await start({ env: { bus } });
     await createNotificationListComponent();
 
     assert.containsOnce(
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/thread_needaction_preview_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/thread_needaction_preview_tests.js
index 7bd70f73b86..bd659c7c8d3 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/thread_needaction_preview_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/thread_needaction_preview_tests.js
@@ -2,7 +2,7 @@
 
 import { afterNextRender, start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('mail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -38,7 +38,6 @@ QUnit.test('mark as read', async function (assert) {
                     "should mark all as read the correct thread"
                 );
             }
-            return this._super(...arguments);
         },
     });
     await createMessagingMenuComponent();
@@ -98,7 +97,6 @@ QUnit.test('click on preview should mark as read and open the thread', async fun
                     "should mark all as read the correct thread"
                 );
             }
-            return this._super(...arguments);
         },
     });
     await createMessagingMenuComponent();
@@ -150,8 +148,9 @@ QUnit.test('click on expand from chat window should close the chat window and op
         notification_type: 'inbox',
         res_partner_id: pyEnv.currentPartnerId,
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { afterEvent, click, createMessagingMenuComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.res_id,
@@ -163,9 +162,7 @@ QUnit.test('click on expand from chat window should close the chat window and op
                 'res.partner',
                 "should redirect to the model of the thread"
             );
-    });
-    const { afterEvent, click, createMessagingMenuComponent } = await start({
-        env: { bus },
+        },
     });
     await createMessagingMenuComponent();
     await afterNextRender(() => afterEvent({
@@ -233,7 +230,6 @@ QUnit.test('[technical] opening a non-channel chat window should not call channe
                 console.error(message);
                 throw Error(message);
             }
-            return this._super(...arguments);
         },
     });
     await createMessagingMenuComponent();
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/thread_preview_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/thread_preview_tests.js
index 9c070589ff8..c5c4614eb40 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/thread_preview_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/thread_preview_tests.js
@@ -34,7 +34,6 @@ QUnit.test('mark as read', async function (assert) {
             if (route.includes('set_last_seen_message')) {
                 assert.step('set_last_seen_message');
             }
-            return this._super(...arguments);
         },
     });
     await createMessagingMenuComponent();
diff --git a/addons/mail/static/tests/qunit_suite_tests/components/thread_view_tests.js b/addons/mail/static/tests/qunit_suite_tests/components/thread_view_tests.js
index 091683fb183..e9e6b29037a 100644
--- a/addons/mail/static/tests/qunit_suite_tests/components/thread_view_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/components/thread_view_tests.js
@@ -252,7 +252,6 @@ QUnit.test('mark channel as fetched when a new message is loaded and as seen whe
                 );
                 assert.step('rpc:set_last_seen_message');
             }
-            return this._super(...arguments);
         }
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -307,7 +306,6 @@ QUnit.test('mark channel as fetched and seen when a new message is loaded if com
     });
     const mailChannelId1 = pyEnv['mail.channel'].create({});
     const { afterEvent, createThreadViewComponent, messaging } = await start({
-        data: this.data,
         mockRPC(route, args) {
             if (args.method === 'channel_fetched' && args.args[0] === mailChannelId1) {
                 throw new Error("'channel_fetched' RPC must not be called for created channel as message is directly seen");
@@ -319,7 +317,6 @@ QUnit.test('mark channel as fetched and seen when a new message is loaded if com
                 );
                 assert.step('rpc:set_last_seen_message');
             }
-            return this._super(...arguments);
         }
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -774,25 +771,20 @@ QUnit.test('should scroll to bottom on receiving new message if the list is init
             res_id: mailChannelId1,
         });
     }
-    const { afterEvent, createThreadViewComponent, messaging } = await start();
+    const { afterEvent, click, createMessagingMenuComponent, messaging } = await start();
     const thread = messaging.models['Thread'].findFromIdentifyingData({
         id: mailChannelId1,
         model: 'mail.channel'
     });
-    const threadViewer = messaging.models['ThreadViewer'].create({
-        hasThreadView: true,
-        qunitTest: insertAndReplace(),
-        thread: replace(thread),
-    });
+    await createMessagingMenuComponent();
+    await click(`.o_MessagingMenu_toggler`);
     await afterEvent({
         eventName: 'o-component-message-list-scrolled',
-        func: () => createThreadViewComponent(
-            threadViewer.threadView,
-            undefined,
-            { isFixedSize: true },
-        ),
-        message: "should wait until channel 20 scrolled initially",
-        predicate: data => threadViewer === data.threadViewer,
+        async func() {
+            await click(`.o_NotificationList_preview`);
+        },
+        message: "should wait until channel scrolled initially",
+        predicate: data => thread === data.threadViewer.thread,
     });
     const initialMessageList = document.querySelector('.o_ThreadView_messageList');
     assert.ok(
@@ -814,8 +806,8 @@ QUnit.test('should scroll to bottom on receiving new message if the list is init
                     uuid: thread.uuid,
                 },
             }),
-        message: "should wait until channel 20 scrolled after receiving a message",
-        predicate: data => threadViewer === data.threadViewer,
+        message: "should wait until channel scrolled after receiving a message",
+        predicate: data => thread === data.threadViewer.thread,
     });
     const messageList = document.querySelector('.o_ThreadView_messageList');
     assert.ok(
@@ -844,25 +836,21 @@ QUnit.test('should not scroll on receiving new message if the list is initially
             res_id: mailChannelId1,
         });
     }
-    const { afterEvent, createThreadViewComponent, messaging } = await start();
+    const { afterEvent, click, createMessagingMenuComponent, messaging } = await start();
     const thread = messaging.models['Thread'].findFromIdentifyingData({
         id: mailChannelId1,
         model: 'mail.channel'
     });
-    const threadViewer = messaging.models['ThreadViewer'].create({
-        hasThreadView: true,
-        qunitTest: insertAndReplace(),
-        thread: replace(thread),
-    });
+
+    await createMessagingMenuComponent();
+    await click(`.o_MessagingMenu_toggler`);
     await afterEvent({
         eventName: 'o-component-message-list-scrolled',
-        func: () => createThreadViewComponent(
-            threadViewer.threadView,
-            undefined,
-            { isFixedSize: true },
-        ),
-        message: "should wait until channel 1 scrolled initially",
-        predicate: data => threadViewer === data.threadViewer,
+        async func() {
+            await click(`.o_NotificationList_preview`);
+        },
+        message: "should wait until channel scrolled initially",
+        predicate: data => thread === data.threadViewer.thread,
     });
     const initialMessageList = document.querySelector('.o_ThreadView_messageList');
     assert.ok(
@@ -874,7 +862,7 @@ QUnit.test('should not scroll on receiving new message if the list is initially
         eventName: 'o-component-message-list-scrolled',
         func: () => initialMessageList.scrollTop = 0,
         message: "should wait until channel 1 processed manual scroll",
-        predicate: data => threadViewer === data.threadViewer,
+        predicate: data => thread === data.threadViewer.thread,
     });
     assert.strictEqual(
         initialMessageList.scrollTop,
@@ -896,8 +884,8 @@ QUnit.test('should not scroll on receiving new message if the list is initially
                     uuid: thread.uuid,
                 },
             }),
-        message: "should wait until channel 20 processed new message hint",
-        predicate: data => threadViewer === data.threadViewer && data.hint.type === 'message-received',
+        message: "should wait until channel processed new message hint",
+        predicate: data => thread === data.threadViewer.thread && data.hint.type === 'message-received',
     });
     assert.strictEqual(
         document.querySelector('.o_ThreadView_messageList').scrollTop,
@@ -1596,9 +1584,8 @@ QUnit.test('failure on loading messages should display error', async function (a
     const { createThreadViewComponent, messaging } = await start({
         async mockRPC(route, args) {
             if (route === '/mail/channel/messages') {
-                throw new Error();
+                return Promise.reject();
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1630,9 +1617,8 @@ QUnit.test('failure on loading messages should prompt retry button', async funct
     const { createThreadViewComponent, messaging } = await start({
         async mockRPC(route, args) {
             if (route === '/mail/channel/messages') {
-                throw new Error();
+                return Promise.reject();
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1679,7 +1665,6 @@ QUnit.test('failure on loading more messages should not alter message list displ
                     throw new Error();
                 }
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1729,7 +1714,6 @@ QUnit.test('failure on loading more messages should display error and prompt ret
                     throw new Error();
                 }
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
@@ -1785,10 +1769,9 @@ QUnit.test('Retry loading more messages on failed load more messages should load
         async mockRPC(route, args) {
             if (route === '/mail/channel/messages') {
                 if (messageFetchShouldFail) {
-                    throw new Error();
+                    return Promise.reject();
                 }
             }
-            return this._super(...arguments);
         },
     });
     const thread = messaging.models['Thread'].findFromIdentifyingData({
diff --git a/addons/mail/static/tests/qunit_suite_tests/m2x_avatar_user_tests.js b/addons/mail/static/tests/qunit_suite_tests/m2x_avatar_user_tests.js
index 57404962f14..2e698c2a938 100644
--- a/addons/mail/static/tests/qunit_suite_tests/m2x_avatar_user_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/m2x_avatar_user_tests.js
@@ -3,13 +3,9 @@
 import { Many2OneAvatarUser } from '@mail/js/m2x_avatar_user';
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 import { click, getFixture, legacyExtraNextTick, patchWithCleanup, triggerHotkey } from "@web/../tests/helpers/utils";
-import { doAction } from '@web/../tests/webclient/helpers';
 import { registry } from "@web/core/registry";
 import { makeLegacyCommandService } from "@web/legacy/utils";
 import core from 'web.core';
-import FormView from 'web.FormView';
-import KanbanView from 'web.KanbanView';
-import ListView from 'web.ListView';
 import session from 'web.session';
 import makeTestEnvironment from "web.test_env";
 import { dom, nextTick } from 'web.test_utils';
@@ -32,14 +28,18 @@ QUnit.module('mail', {}, function () {
         const resPartnerId1 = pyEnv['res.partner'].create({ display_name: 'Partner 1' });
         const resUsersId1 = pyEnv['res.users'].create({ name: "Mario", partner_id: resPartnerId1 });
         pyEnv['m2x.avatar.user'].create({ user_id: resUsersId1 });
-        const { widget: list } = await start({
-            hasView: true,
-            View: ListView,
-            model: 'm2x.avatar.user',
-            arch: '<tree><field name="user_id" widget="many2one_avatar_user"/></tree>',
+        const views = {
+            'm2x.avatar.user,false,list': '<tree><field name="user_id" widget="many2one_avatar_user"/></tree>',
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.user',
+            views: [[false, "list"]],
         });
 
-        await dom.click(list.$('.o_data_cell:nth(0) .o_m2o_avatar > img'));
+        await dom.click(document.querySelector('.o_data_cell .o_m2o_avatar > img'));
         assert.containsOnce(document.body, '.o_ChatWindow', 'Chat window should be opened');
         assert.strictEqual(
             document.querySelector('.o_ChatWindowHeader_name').textContent,
@@ -55,12 +55,16 @@ QUnit.module('mail', {}, function () {
         const resPartnerId1 = pyEnv['res.partner'].create({ display_name: 'Partner 1' });
         const resUsersId1 = pyEnv['res.users'].create({ name: "Mario", partner_id: resPartnerId1 });
         const m2xAvatarUserId1 = pyEnv['m2x.avatar.user'].create({ user_ids: [resUsersId1] });
-        await start({
-            hasView: true,
-            View: FormView,
-            model: 'm2x.avatar.user',
-            arch: '<form><field name="user_ids" widget="many2many_avatar_user"/></form>',
+        const views = {
+            'm2x.avatar.user,false,form': '<form><field name="user_ids" widget="many2many_avatar_user"/></form>',
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.user',
             res_id: m2xAvatarUserId1,
+            views: [[false, 'form']],
         });
 
         await dom.click(document.querySelector('.o_field_many2manytags.avatar .badge .o_m2m_avatar'));
@@ -80,13 +84,9 @@ QUnit.module('mail', {}, function () {
             [{ name: "Mario" }, { name: "Yoshi" }, { name: "Luigi" }, { name: "Tapu" }],
         );
         pyEnv['m2x.avatar.user'].create({ user_ids: resUsersIds });
-
-        await start({
-            hasView: true,
-            View: KanbanView,
-            model: 'm2x.avatar.user',
-            arch: `
-                <kanban>
+        const views = {
+            'm2x.avatar.user,false,kanban':
+                `<kanban>
                     <templates>
                         <t t-name="kanban-box">
                             <div>
@@ -102,6 +102,13 @@ QUnit.module('mail', {}, function () {
                         </t>
                     </templates>
                 </kanban>`,
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.user',
+            views: [[false, 'kanban']],
         });
 
         assert.containsOnce(document.body, '.o_kanban_record .o_field_many2manytags .o_m2m_avatar_empty',
@@ -131,10 +138,9 @@ QUnit.module('mail', {}, function () {
 
         const views = {
             'm2x.avatar.user,false,form': '<form><field name="user_id" widget="many2one_avatar_user"/></form>',
-            'm2x.avatar.user,false,search': '<search></search>',
         };
-        const { widget: webClient } = await start({ hasWebClient: true, serverData: { views } });
-        await doAction(webClient, {
+        const { openView } = await start({ serverData: { views } });
+        await openView({
             res_id: m2xAvatarUserId1,
             type: 'ir.actions.act_window',
             target: 'current',
@@ -176,10 +182,9 @@ QUnit.module('mail', {}, function () {
 
         const views = {
             'm2x.avatar.user,false,form': '<form><field name="user_id" widget="many2one_avatar_user"/></form>',
-            'm2x.avatar.user,false,search': '<search></search>',
         };
-        const { widget: webClient } = await start({ hasWebClient: true, serverData: { views } });
-        await doAction(webClient, {
+        const { openView } = await start({ serverData: { views } });
+        await openView({
             res_id: m2xAvatarUserId1,
             type: 'ir.actions.act_window',
             target: 'current',
@@ -220,10 +225,9 @@ QUnit.module('mail', {}, function () {
 
         const views = {
             'm2x.avatar.user,false,form': '<form><field name="user_ids" widget="many2many_avatar_user"/></form>',
-            'm2x.avatar.user,false,search': '<search></search>',
         };
-        const { widget: webClient } = await start({ hasWebClient: true, serverData: { views } });
-        await doAction(webClient, {
+        const { openView } = await start({ serverData: { views } });
+        await openView({
             res_id: m2xAvatarUserId1,
             type: 'ir.actions.act_window',
             target: 'current',
@@ -268,10 +272,9 @@ QUnit.module('mail', {}, function () {
 
         const views = {
             'm2x.avatar.user,false,form': '<form><field name="user_ids" widget="many2many_avatar_user"/></form>',
-            'm2x.avatar.user,false,search': '<search></search>',
         };
-        const { widget: webClient } = await start({ hasWebClient: true, serverData: { views } });
-        await doAction(webClient, {
+        const { openView } = await start({ serverData: { views } });
+        await openView({
             res_id: m2xAvatarUserId1,
             type: 'ir.actions.act_window',
             target: 'current',
@@ -308,12 +311,16 @@ QUnit.module('mail', {}, function () {
         const pyEnv = await startServer();
         const resUsersId1 = pyEnv['res.users'].create({ name: "Mario" });
         const m2xAvatarUserId1 = pyEnv['m2x.avatar.user'].create({ user_id: resUsersId1 });
-        await start({
-            hasView: true,
-            View: ListView,
-            model: 'm2x.avatar.user',
-            arch: '<tree><field name="user_id" widget="many2one_avatar_user"/></tree>',
+        const views = {
+            'm2x.avatar.user,false,list': '<tree><field name="user_id" widget="many2one_avatar_user"/></tree>',
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.user',
             res_id: m2xAvatarUserId1,
+            views: [[false, 'list']],
         });
         assert.strictEqual(
             document.querySelector('.o_m2o_avatar > img').getAttribute('data-src'),
@@ -328,20 +335,25 @@ QUnit.module('mail', {}, function () {
         const pyEnv = await startServer();
         const resUsersId1 = pyEnv['res.users'].create({ name: "Mario" });
         const m2xAvatarUserId1 = pyEnv['m2x.avatar.user'].create({ user_id: resUsersId1 });
-        await start({
-            hasView: true,
-            View: KanbanView,
-            model: 'm2x.avatar.user',
-            arch: `<kanban>
-                        <templates>
-                            <t t-name="kanban-box">
-                                <div>
-                                    <field name="user_id" widget="many2one_avatar_user"/>
-                                </div>
-                            </t>
-                        </templates>
-                    </kanban>`,
+        const views = {
+            'm2x.avatar.user,false,kanban':
+                `<kanban>
+                    <templates>
+                        <t t-name="kanban-box">
+                            <div>
+                                <field name="user_id" widget="many2one_avatar_user"/>
+                            </div>
+                        </t>
+                    </templates>
+                </kanban>`,
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.user',
             res_id: m2xAvatarUserId1,
+            views: [[false, 'kanban']],
         });
         assert.strictEqual(
             document.querySelector('.o_m2o_avatar > img').getAttribute('data-src'),
@@ -356,12 +368,16 @@ QUnit.module('mail', {}, function () {
         const pyEnv = await startServer();
         const resUsersId1 = pyEnv['res.users'].create({ name: "Mario" });
         const m2xAvatarUserId1 = pyEnv['m2x.avatar.user'].create({ user_ids: [resUsersId1] });
-        await start({
-            hasView: true,
-            View: FormView,
-            model: 'm2x.avatar.user',
-            arch: '<form><field name="user_ids" widget="many2many_avatar_user"/></form>',
+        const views = {
+            'm2x.avatar.user,false,form': '<form><field name="user_ids" widget="many2many_avatar_user"/></form>',
+        };
+        const { openView } = await start({
+            serverData: { views },
+        });
+        await openView({
+            res_model: 'm2x.avatar.user',
             res_id: m2xAvatarUserId1,
+            views: [[false, 'form']],
         });
         assert.strictEqual(
             document.querySelector('.o_field_many2manytags.avatar.o_field_widget .badge img').getAttribute('data-src'),
diff --git a/addons/mail/static/tests/qunit_suite_tests/models/messaging_tests.js b/addons/mail/static/tests/qunit_suite_tests/models/messaging_tests.js
index 6fdb47a2f4f..37b15b676e6 100644
--- a/addons/mail/static/tests/qunit_suite_tests/models/messaging_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/models/messaging_tests.js
@@ -2,6 +2,8 @@
 
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 
+import { makeFakeNotificationService } from "@web/../tests/helpers/mock_services";
+
 QUnit.module('mail', {}, function () {
 QUnit.module('models', {}, function () {
 QUnit.module('messaging_tests.js', {}, function () {
@@ -13,19 +15,17 @@ QUnit.test('openChat: display notification for partner without user', async func
     const resPartnerId1 = pyEnv['res.partner'].create();
     const { messaging } = await start({
         services: {
-            notification: {
-                notify(notification) {
-                    assert.ok(
-                        true,
-                        "should display a toast notification after failing to open chat"
-                    );
-                    assert.strictEqual(
-                        notification.message,
-                        "You can only chat with partners that have a dedicated user.",
-                        "should display the correct information in the notification"
-                    );
-                },
-            },
+            notification: makeFakeNotificationService(message => {
+                assert.ok(
+                    true,
+                    "should display a toast notification after failing to open chat"
+                );
+                assert.strictEqual(
+                    message,
+                    "You can only chat with partners that have a dedicated user.",
+                    "should display the correct information in the notification"
+                );
+            }),
         },
     });
 
@@ -39,19 +39,17 @@ QUnit.test('openChat: display notification for wrong user', async function (asse
     pyEnv['res.users'].create();
     const { messaging } = await start({
         services: {
-            notification: {
-                notify(notification) {
-                    assert.ok(
-                        true,
-                        "should display a toast notification after failing to open chat"
-                    );
-                    assert.strictEqual(
-                        notification.message,
-                        "You can only chat with existing users.",
-                        "should display the correct information in the notification"
-                    );
-                },
-            },
+            notification: makeFakeNotificationService(message => {
+                assert.ok(
+                    true,
+                    "should display a toast notification after failing to open chat"
+                );
+                assert.strictEqual(
+                    message,
+                    "You can only chat with existing users.",
+                    "should display the correct information in the notification"
+                );
+            }),
         },
     });
 
diff --git a/addons/mail/static/tests/qunit_suite_tests/webclient/commands/mail_providers_tests.js b/addons/mail/static/tests/qunit_suite_tests/webclient/commands/mail_providers_tests.js
index 5d4832284d8..3c2e86da808 100644
--- a/addons/mail/static/tests/qunit_suite_tests/webclient/commands/mail_providers_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/webclient/commands/mail_providers_tests.js
@@ -28,7 +28,6 @@ QUnit.module('mail', {}, function () {
 
         const target = getFixture();
         await start({
-            hasWebClient: true,
             target,
         });
         triggerHotkey("control+k");
@@ -53,7 +52,6 @@ QUnit.module('mail', {}, function () {
         });
         const target = getFixture();
         await start({
-            hasWebClient: true,
             target,
         });
         triggerHotkey("control+k");
diff --git a/addons/mail/static/tests/qunit_suite_tests/widgets/form_renderer_tests.js b/addons/mail/static/tests/qunit_suite_tests/widgets/form_renderer_tests.js
index 2f9a9a56989..848a07a0e8a 100644
--- a/addons/mail/static/tests/qunit_suite_tests/widgets/form_renderer_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/widgets/form_renderer_tests.js
@@ -11,7 +11,6 @@ import {
 } from '@mail/../tests/helpers/test_utils';
 
 import fieldRegistry from 'web.field_registry';
-import FormView from 'web.FormView';
 import { dom, nextTick } from 'web.test_utils';
 import { registerCleanup } from "@web/../tests/helpers/cleanup";
 
@@ -19,32 +18,7 @@ const { triggerEvent } = dom;
 
 QUnit.module('mail', {}, function () {
 QUnit.module('widgets', {}, function () {
-QUnit.module('form_renderer_tests.js', {
-    async beforeEach() {
-        // FIXME archs could be removed once task-2248306 is done
-        // The mockServer will try to get the list view
-        // of every relational fields present in the main view.
-        // In the case of mail fields, we don't really need them,
-        // but they still need to be defined.
-        this.createView = async (viewParams, ...args) => {
-            const startResult = makeDeferred();
-            await afterNextRender(async () => {
-                const viewArgs = Object.assign(
-                    {
-                        archs: {
-                            'mail.activity,false,list': '<tree/>',
-                            'mail.followers,false,list': '<tree/>',
-                            'mail.message,false,list': '<tree/>',
-                        },
-                    },
-                    viewParams,
-                );
-                startResult.resolve(await start(viewArgs, ...args));
-            });
-            return startResult;
-        };
-    },
-});
+QUnit.module('form_renderer_tests.js');
 
 QUnit.test('[technical] spinner when messaging is not created', async function (assert) {
     /**
@@ -61,22 +35,24 @@ QUnit.test('[technical] spinner when messaging is not created', async function (
     const resPartnerId1 = pyEnv['res.partner'].create({
         display_name: "second partner",
     });
-    await this.createView({
-        hasView: true,
-        messagingBeforeCreationDeferred: makeDeferred(), // block messaging creation
-        waitUntilMessagingCondition: 'none',
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter"></div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        messagingBeforeCreationDeferred: makeDeferred(), // block messaging creation
+        serverData: { views },
+        waitUntilMessagingCondition: 'none',
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -111,29 +87,29 @@ QUnit.test('[technical] keep spinner on transition from messaging non-created to
     const resPartnerId1 = pyEnv['res.partner'].create({
         display_name: "second partner",
     });
-    await this.createView({
-        hasView: true,
-        messagingBeforeCreationDeferred,
-        async mockRPC(route, args) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
-            if (route === '/mail/init_messaging') {
-                await new Promise(() => {}); // simulate messaging never initialized
-            }
-            return _super();
-        },
-        waitUntilMessagingCondition: 'none',
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter"></div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        messagingBeforeCreationDeferred,
+        async mockRPC(route, args) {
+            if (route === '/mail/init_messaging') {
+                await new Promise(() => {}); // simulate messaging never initialized
+            }
+        },
+        serverData: { views },
+        waitUntilMessagingCondition: 'none',
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.strictEqual(
         document.querySelector('.o_ChatterContainer').textContent,
@@ -168,28 +144,28 @@ QUnit.test('spinner when messaging is created but not initialized', async functi
     const resPartnerId1 = pyEnv['res.partner'].create({
         display_name: "second partner",
     });
-    await this.createView({
-        hasView: true,
-        async mockRPC(route, args) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
-            if (route === '/mail/init_messaging') {
-                await new Promise(() => {}); // simulate messaging never initialized
-            }
-            return _super();
-        },
-        waitUntilMessagingCondition: 'created',
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter"></div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        async mockRPC(route, args) {
+            if (route === '/mail/init_messaging') {
+                await new Promise(() => {}); // simulate messaging never initialized
+            }
+        },
+        serverData: { views },
+        waitUntilMessagingCondition: 'created',
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -216,28 +192,28 @@ QUnit.test('transition non-initialized messaging to initialized messaging: displ
     const resPartnerId1 = pyEnv['res.partner'].create({
         display_name: "second partner",
     });
-    await this.createView({
-        hasView: true,
-        async mockRPC(route, args) {
-            const _super = this._super.bind(this, ...arguments); // limitation of class.js
-            if (route === '/mail/init_messaging') {
-                await messagingBeforeInitializationDeferred;
-            }
-            return _super();
-        },
-        waitUntilMessagingCondition: 'created',
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter"></div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        async mockRPC(route, args) {
+            if (route === '/mail/init_messaging') {
+                await messagingBeforeInitializationDeferred;
+            }
+        },
+        serverData: { views },
+        waitUntilMessagingCondition: 'created',
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.strictEqual(
         document.querySelector('.o_ChatterContainer').textContent,
@@ -264,20 +240,22 @@ QUnit.test('basic chatter rendering', async function (assert) {
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create({ display_name: "second partner" });
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter"></div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.strictEqual(
         document.querySelectorAll(`.o_Chatter`).length,
@@ -291,13 +269,9 @@ QUnit.test('basic chatter rendering without followers', async function (assert)
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create({ display_name: "second partner" });
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -305,9 +279,15 @@ QUnit.test('basic chatter rendering without followers', async function (assert)
                     <field name="activity_ids"/>
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -346,13 +326,9 @@ QUnit.test('basic chatter rendering without activities', async function (assert)
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create({ display_name: "second partner" });
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -360,9 +336,15 @@ QUnit.test('basic chatter rendering without activities', async function (assert)
                     <field name="message_follower_ids"/>
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -401,13 +383,9 @@ QUnit.test('basic chatter rendering without messages', async function (assert) {
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create({ display_name: "second partner" });
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
@@ -415,9 +393,15 @@ QUnit.test('basic chatter rendering without messages', async function (assert) {
                     <field name="message_follower_ids"/>
                     <field name="activity_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
         res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -460,37 +444,36 @@ QUnit.test('chatter updating', async function (assert) {
         { display_name: "second partner" },
     ]);
     pyEnv['mail.message'].create({ body: "not empty", model: 'res.partner', res_id: resPartnerId2 });
-    const { afterEvent } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        res_id: resPartnerId1,
-        viewOptions: {
-            ids: [resPartnerId1, resPartnerId2],
-            index: 0,
-        },
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
-        waitUntilEvent: {
-            eventName: 'o-thread-view-hint-processed',
-            message: "should wait until partner 11 thread loaded messages initially",
-            predicate: ({ hint, threadViewer }) => {
-                return (
-                    hint.type === 'messages-loaded' &&
-                    threadViewer.thread.model === 'res.partner' &&
-                    threadViewer.thread.id === resPartnerId1
-                );
-            },
-        }
+            </form>`,
+    };
+    const { afterEvent, openView } = await start({
+        serverData: { views },
+    });
+    const openViewAction = {
+        res_model: 'res.partner',
+        res_id: resPartnerId1,
+        views: [[false, 'form']],
+    };
+    await afterEvent({
+        eventName: 'o-thread-view-hint-processed',
+        func: () => openView(openViewAction, { resIds: [resPartnerId1, resPartnerId2] }),
+        message: "should wait until partner 11 thread loaded messages initially",
+        predicate: ({ hint, threadViewer }) => {
+            return (
+                hint.type === 'messages-loaded' &&
+                threadViewer.thread.model === 'res.partner' &&
+                threadViewer.thread.id === resPartnerId1
+            );
+        },
     });
     await afterNextRender(() => afterEvent({
         eventName: 'o-thread-view-hint-processed',
@@ -514,24 +497,23 @@ QUnit.test('chatter updating', async function (assert) {
 QUnit.test('chatter should become enabled when creation done', async function (assert) {
     assert.expect(10);
 
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
-        viewOptions: {
-            mode: 'edit',
-        },
+            </form>`,
+    };
+    const { click, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
+        views: [[false, 'form']],
     });
     assert.containsOnce(
         document.body,
@@ -606,27 +588,30 @@ QUnit.test('read more/less links are not duplicated when switching from read to
         model: 'res.partner',
         res_id: resPartnerId1,
     });
-    const { afterEvent } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        res_id: resPartnerId1,
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
-        waitUntilEvent: {
-            eventName: 'o-component-message-read-more-less-inserted',
-            message: "should wait until read more/less is inserted initially",
-            predicate: ({ message }) => message.id === mailMessageId1,
-        },
+            </form>`,
+    };
+    const { afterEvent, openView } = await start({
+        serverData: { views },
+    });
+    const openViewAction = {
+        res_model: 'res.partner',
+        res_id: resPartnerId1,
+        views: [[false, 'form']],
+    };
+    await afterEvent({
+        func: () => openView(openViewAction),
+        eventName: 'o-component-message-read-more-less-inserted',
+        message: "should wait until read more/less is inserted initially",
+        predicate: ({ message }) => message.id === mailMessageId1,
     });
     assert.containsOnce(
         document.body,
@@ -691,27 +676,30 @@ QUnit.test('read more links becomes read less after being clicked', async functi
         model: 'res.partner',
         res_id: resPartnerId1,
     }]);
-    const { afterEvent } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        res_id: resPartnerId1,
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
-        waitUntilEvent: {
-            eventName: 'o-component-message-read-more-less-inserted',
-            message: "should wait until read more/less is inserted initially",
-            predicate: ({ message }) => message.id === mailMessageId1,
-        },
+            </form>`,
+    };
+    const { afterEvent, openView } = await start({
+        serverData: { views },
+    });
+    const openViewAction = {
+        res_model: 'res.partner',
+        res_id: resPartnerId1,
+        views: [[false, 'form']],
+    };
+    await afterEvent({
+        func: () => openView(openViewAction),
+        eventName: 'o-component-message-read-more-less-inserted',
+        message: "should wait until read more/less is inserted initially",
+        predicate: ({ message }) => message.id === mailMessageId1,
     });
     assert.containsOnce(
         document.body,
@@ -775,15 +763,9 @@ QUnit.test('Form view not scrolled when switching record', async function (asser
         };
     });
     pyEnv['mail.message'].create(messages);
-
-    patchUiSize({ size: SIZES.LG });
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                     <field name="description"/>
@@ -791,13 +773,22 @@ QUnit.test('Form view not scrolled when switching record', async function (asser
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
-        viewOptions: {
-            currentId: resPartnerId1,
-            ids: [resPartnerId1, resPartnerId2],
-        },
+            </form>`,
+    };
+    patchUiSize({ size: SIZES.LG });
+    const { click, openView } = await start({
+        serverData: { views },
     });
+    await openView(
+        {
+            res_model: 'res.partner',
+            res_id: resPartnerId1,
+            views: [[false, 'form']],
+        },
+        {
+            resIds: [resPartnerId1, resPartnerId2],
+        }
+    );
 
     const controllerContentEl = document.querySelector('.o_content');
 
@@ -861,27 +852,31 @@ QUnit.test('Attachments that have been unlinked from server should be visually u
             res_model: 'res.partner',
         },
     ]);
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        res_id: resPartnerId1,
-        viewOptions: {
-            ids: [resPartnerId1, resPartnerId2],
-            index: 0,
-        },
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { click, openView } = await start({
+        serverData: { views },
     });
+    await openView(
+        {
+            res_model: 'res.partner',
+            res_id: resPartnerId1,
+            views: [[false, 'form']],
+        },
+        {
+            currentId: resPartnerId1,
+            resIds: [resPartnerId1, resPartnerId2],
+        },
+    );
     assert.strictEqual(
         document.querySelector('.o_ChatterTopbar_buttonCount').textContent,
         '2',
@@ -906,18 +901,24 @@ QUnit.test('chatter just contains "creating a new record" message during the cre
 
     const pyEnv = await startServer();
     const resPartnerId1 = pyEnv['res.partner'].create();
-    const { click } = await this.createView({
-        hasView: true,
-        View: FormView,
-        model: 'res.partner',
-        res_id: resPartnerId1,
-        arch: `
-            <form>
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
+                <sheet>
+                    <field name="name"/>
+                </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { click, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
+        res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
 
     await click('.o_form_button_create');
@@ -964,22 +965,24 @@ QUnit.test('[TECHNICAL] unfolded read more/less links should not fold on message
         model: 'res.partner',
         res_id: resPartnerId1,
     });
-    const { click } = await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        res_id: resPartnerId1,
-        arch: `
-            <form string="Partners">
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
                     <field name="name"/>
                 </sheet>
                 <div class="oe_chatter">
                     <field name="message_ids"/>
                 </div>
-            </form>
-        `,
+            </form>`,
+    };
+    const { click, openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'res.partner',
+        res_id: resPartnerId1,
+        views: [[false, 'form']],
     });
     assert.strictEqual(
         document.querySelector('.o_Message_readMoreLess').textContent,
@@ -1022,24 +1025,23 @@ QUnit.test('chatter does not flicker when the form view is re-rendered', async f
         delete fieldRegistry.map.async_widget;
     });
 
-    await this.createView({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'res.partner',
-        arch: `
-            <form>
+    const views = {
+        'res.partner,false,form':
+            `<form string="Partners">
                 <sheet>
-                    <field name="name" widget="async_widget"/>
+                    <field name="name"/>
                 </sheet>
                 <div class="oe_chatter"></div>
-            </form>
-        `,
-        viewOptions: {
-            currentId: resPartnerId1,
-            ids: [resPartnerId1, resPartnerId2],
-        },
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
     });
+    await openView({
+        res_model: 'res.partner',
+        res_id: resPartnerId1,
+        views: [[false, 'form']],
+    }, { resIds: [resPartnerId1, resPartnerId2]});
     assert.strictEqual(
         document.querySelectorAll(`.o_Chatter`).length,
         1,
diff --git a/addons/mail/static/tests/qunit_suite_tests/widgets/notification_alert_tests.js b/addons/mail/static/tests/qunit_suite_tests/widgets/notification_alert_tests.js
index d6109aa3a0a..ebd3a67fa3d 100644
--- a/addons/mail/static/tests/qunit_suite_tests/widgets/notification_alert_tests.js
+++ b/addons/mail/static/tests/qunit_suite_tests/widgets/notification_alert_tests.js
@@ -3,36 +3,30 @@
 import { start } from '@mail/../tests/helpers/test_utils';
 
 import { browser } from '@web/core/browser/browser';
-import { patchWithCleanup } from '@web/../tests/helpers/utils';
-
-import FormView from 'web.FormView';
+import { patchWithCleanup } from "@web/../tests/helpers/utils";
 
 QUnit.module('mail', {}, function () {
 QUnit.module('widgets', {}, function () {
 QUnit.module('notification_alert_tests.js');
 
-QUnit.skip('notification_alert widget: display blocked notification alert', async function (assert) {
-    // FIXME: Test should work, but for some reasons OWL always flags the
-    // component as not mounted, even though it is in the DOM and it's state
-    // is good for rendering... task-227947
+QUnit.test('notification_alert widget: display blocked notification alert', async function (assert) {
     assert.expect(1);
 
+    const views = {
+        'mail.message,false,form': `<form><widget name="notification_alert"/></form>`,
+    };
     patchWithCleanup(browser, {
         Notification: {
             ...browser.Notification,
             permission: 'denied',
         },
     });
-    await start({
-        arch: `
-            <form>
-                <widget name="notification_alert"/>
-            </form>
-        `,
-        hasView: true,
-        model: 'mail.message',
-        // View params
-        View: FormView,
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'mail.message',
+        views: [[false, 'form']],
     });
 
     assert.containsOnce(
@@ -45,21 +39,20 @@ QUnit.skip('notification_alert widget: display blocked notification alert', asyn
 QUnit.test('notification_alert widget: no notification alert when granted', async function (assert) {
     assert.expect(1);
 
+    const views = {
+        'mail.message,false,form': `<form><widget name="notification_alert"/></form>`,
+    };
     patchWithCleanup(browser, {
         Notification: {
             permission: 'granted',
         },
     });
-    await start({
-        arch: `
-            <form>
-                <widget name="notification_alert"/>
-            </form>
-        `,
-        hasView: true,
-        model: 'mail.message',
-        // View params
-        View: FormView,
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'mail.message',
+        views: [[false, 'form']],
     });
 
     assert.containsNone(
@@ -72,21 +65,20 @@ QUnit.test('notification_alert widget: no notification alert when granted', asyn
 QUnit.test('notification_alert widget: no notification alert when default', async function (assert) {
     assert.expect(1);
 
+    const views = {
+        'mail.message,false,form': `<form><widget name="notification_alert"/></form>`,
+    };
     patchWithCleanup(browser, {
         Notification: {
             permission: 'default',
         },
     });
-    await start({
-        arch: `
-            <form>
-                <widget name="notification_alert"/>
-            </form>
-        `,
-        hasView: true,
-        model: 'mail.message',
-        // View params
-        View: FormView,
+    const { openView } = await start({
+        serverData: { views },
+    });
+    await openView({
+        res_model: 'mail.message',
+        views: [[false, 'form']],
     });
 
     assert.containsNone(
diff --git a/addons/mail/static/tests/tours/mail_full_composer_test_tour.js b/addons/mail/static/tests/tours/mail_full_composer_test_tour.js
index 2d81a67cf33..7af58fa351c 100644
--- a/addons/mail/static/tests/tours/mail_full_composer_test_tour.js
+++ b/addons/mail/static/tests/tours/mail_full_composer_test_tour.js
@@ -7,8 +7,6 @@ import {
 
 import tour from 'web_tour.tour';
 
-const { Component } = owl;
-
 /**
  * This tour depends on data created by python test in charge of launching it.
  * It is not intended to work when launched from interface. It is needed to test
@@ -33,7 +31,7 @@ tour.register('mail/static/tests/tours/mail_full_composer_test_tour.js', {
             contentType: 'text/plain',
             name: 'text.txt',
         });
-        const messaging = await Component.env.services.messaging.get();
+        const messaging = await odoo.__DEBUG__.messaging;
         const uploaders = messaging.models['FileUploader'].all();
         inputFiles(
             uploaders[0].fileInput,
diff --git a/addons/mail/views/mail_channel_views.xml b/addons/mail/views/mail_channel_views.xml
index a9794d0bda7..5bc0894c7fd 100644
--- a/addons/mail/views/mail_channel_views.xml
+++ b/addons/mail/views/mail_channel_views.xml
@@ -128,8 +128,7 @@
 
     <record id="action_discuss" model="ir.actions.client">
         <field name="name">Discuss</field>
-        <field name="tag">mail.widgets.discuss</field>
-        <field name="res_model">mail.channel</field>
+        <field name="tag">mail.action_discuss</field>
         <field name="params" eval="&quot;{ 'default_active_id': 'mail.box_inbox' }&quot;"/>
     </record>
 
diff --git a/addons/note/static/tests/helpers/mock_server.js b/addons/note/static/tests/helpers/mock_server.js
index b03178d4629..9b41cf2ffa1 100644
--- a/addons/note/static/tests/helpers/mock_server.js
+++ b/addons/note/static/tests/helpers/mock_server.js
@@ -2,10 +2,13 @@
 
 // ensure mail override is applied first.
 import '@mail/../tests/helpers/mock_server';
-import MockServer from 'web.MockServer';
+
+import { patch } from '@web/core/utils/patch';
+import { MockServer } from '@web/../tests/helpers/mock_server';
+
 import { date_to_str } from 'web.time';
 
-MockServer.include({
+patch(MockServer.prototype, 'note', {
     //--------------------------------------------------------------------------
     // Private
     //--------------------------------------------------------------------------
@@ -13,7 +16,7 @@ MockServer.include({
     /**
      * @override
      */
-    async _performRpc(route, args) {
+    async _performRPC(route, args) {
         if (route === '/note/new') {
             return this._mockRouteNoteNew(args);
         }
diff --git a/addons/note/static/tests/systray_activity_menu_tests.js b/addons/note/static/tests/systray_activity_menu_tests.js
index 26c9567ef38..84d838e0daf 100644
--- a/addons/note/static/tests/systray_activity_menu_tests.js
+++ b/addons/note/static/tests/systray_activity_menu_tests.js
@@ -16,7 +16,7 @@ QUnit.test('note activity menu widget: create note from activity menu', async fu
     legacySystrayItems.push(ActivityMenu);
     registerCleanup(() => legacySystrayItems.pop());
 
-    await start({ hasWebClient: true });
+    await start();
     assert.containsOnce(document.body, '.o_mail_systray_item',
         'should contain an instance of widget');
     await testUtils.nextTick();
diff --git a/addons/project/__manifest__.py b/addons/project/__manifest__.py
index 38f3689918a..85e4b1b4c31 100644
--- a/addons/project/__manifest__.py
+++ b/addons/project/__manifest__.py
@@ -113,7 +113,7 @@
 
             # Remove Longpolling bus and packages needed this bus
             ('remove', 'bus/static/src/js/services/assets_watchdog_service.js'),
-            ('remove', 'mail/static/src/services/messaging/messaging.js'),
+            ('remove', 'mail/static/src/services/messaging_service.js'),
 
             ('remove', 'mail/static/src/components/dialog_manager/dialog_manager.js'),
             ('remove', 'mail/static/src/components/chat_window_manager/chat_window_manager.js'),
diff --git a/addons/sms/static/src/models/message.js b/addons/sms/static/src/models/message.js
index b26a1b92e86..1ff1604bac8 100644
--- a/addons/sms/static/src/models/message.js
+++ b/addons/sms/static/src/models/message.js
@@ -10,14 +10,14 @@ patchRecordMethods('Message', {
      */
     openResendAction() {
         if (this.message_type === 'sms') {
-            this.env.bus.trigger('do-action', {
-                action: 'sms.sms_resend_action',
-                options: {
+            this.env.services.action.doAction(
+                'sms.sms_resend_action',
+                {
                     additional_context: {
                         default_mail_message_id: this.id,
                     },
                 },
-            });
+            );
         } else {
             this._super(...arguments);
         }
diff --git a/addons/sms/static/src/models/notification_group.js b/addons/sms/static/src/models/notification_group.js
index cbc3fca0a85..47dba868aa9 100644
--- a/addons/sms/static/src/models/notification_group.js
+++ b/addons/sms/static/src/models/notification_group.js
@@ -12,17 +12,15 @@ patchRecordMethods('NotificationGroup', {
         if (this.notification_type !== 'sms') {
             return this._super(...arguments);
         }
-        this.env.bus.trigger('do-action', {
-            action: {
-                name: this.env._t("SMS Failures"),
-                type: 'ir.actions.act_window',
-                view_mode: 'kanban,list,form',
-                views: [[false, 'kanban'], [false, 'list'], [false, 'form']],
-                target: 'current',
-                res_model: this.res_model,
-                domain: [['message_has_sms_error', '=', true]],
-                context: { create: false },
-            },
+        this.env.services.action.doAction({
+            name: this.env._t("SMS Failures"),
+            type: 'ir.actions.act_window',
+            view_mode: 'kanban,list,form',
+            views: [[false, 'kanban'], [false, 'list'], [false, 'form']],
+            target: 'current',
+            res_model: this.res_model,
+            domain: [['message_has_sms_error', '=', true]],
+            context: { create: false },
         });
         if (this.messaging.device.isSmall) {
             // messaging menu has a higher z-index than views so it must
diff --git a/addons/sms/static/tests/qunit_suite_tests/components/message_tests.js b/addons/sms/static/tests/qunit_suite_tests/components/message_tests.js
index 140424510de..1316023bd85 100644
--- a/addons/sms/static/tests/qunit_suite_tests/components/message_tests.js
+++ b/addons/sms/static/tests/qunit_suite_tests/components/message_tests.js
@@ -8,7 +8,7 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('sms', {}, function () {
 QUnit.module('components', {}, function () {
@@ -113,8 +113,9 @@ QUnit.test('Notification Error', async function (assert) {
         notification_type: 'sms',
         res_partner_id: resPartnerId1,
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action, options }) => {
+    const { createThreadViewComponent, env, messaging } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('do_action');
             assert.strictEqual(
                 action,
@@ -127,8 +128,8 @@ QUnit.test('Notification Error', async function (assert) {
                 "action should have correct message id"
             );
             openResendActionDef.resolve();
+        },
     });
-    const { createThreadViewComponent, messaging } = await start({ env: { bus } });
     const threadViewer = messaging.models['ThreadViewer'].create({
         hasThreadView: true,
         qunitTest: insertAndReplace(),
diff --git a/addons/sms/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js b/addons/sms/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
index caec4220c22..3446c13a73a 100644
--- a/addons/sms/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
+++ b/addons/sms/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
@@ -2,7 +2,7 @@
 
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('sms', {}, function () {
 QUnit.module('components', {}, function () {
@@ -189,8 +189,9 @@ QUnit.test('grouped notifications by document model', async function (assert) {
             notification_type: 'sms', // expected failure type for sms message
         },
     ]);
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { createNotificationListComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.name,
@@ -227,9 +228,9 @@ QUnit.test('grouped notifications by document model', async function (assert) {
                 JSON.stringify([['message_has_sms_error', '=', true]]),
                 "action should have 'message_has_sms_error' as domain"
             );
+        },
     });
 
-    const { createNotificationListComponent } = await start({ env: { bus } });
     await createNotificationListComponent();
 
     assert.containsOnce(
diff --git a/addons/snailmail/static/src/models/message.js b/addons/snailmail/static/src/models/message.js
index 0c9d599e69d..2fa26471909 100644
--- a/addons/snailmail/static/src/models/message.js
+++ b/addons/snailmail/static/src/models/message.js
@@ -22,14 +22,14 @@ addRecordMethods('Message', {
      * Opens the action about 'snailmail.letter' format error.
      */
     openFormatLetterAction() {
-        this.env.bus.trigger('do-action', {
-            action: 'snailmail.snailmail_letter_format_error_action',
-            options: {
+        this.env.services.action.doAction(
+            'snailmail.snailmail_letter_format_error_action',
+            {
                 additional_context: {
                     message_id: this.id,
                 },
             },
-        });
+        );
     },
     /**
      * Opens the action about 'snailmail.letter' missing fields.
@@ -40,14 +40,14 @@ addRecordMethods('Message', {
             method: 'search',
             args: [[['message_id', '=', this.id]]],
         });
-        this.env.bus.trigger('do-action', {
-            action: 'snailmail.snailmail_letter_missing_required_fields_action',
-            options: {
+        this.env.services.action.doAction(
+            'snailmail.snailmail_letter_missing_required_fields_action',
+            {
                 additional_context: {
                     default_letter_id: letterIds[0],
                 },
-            },
-        });
+            }
+        );
     },
     /**
      * Retries to send the 'snailmail.letter' corresponding to this message.
diff --git a/addons/snailmail/static/src/models/notification_group.js b/addons/snailmail/static/src/models/notification_group.js
index c5b135a617e..db8254cfaed 100644
--- a/addons/snailmail/static/src/models/notification_group.js
+++ b/addons/snailmail/static/src/models/notification_group.js
@@ -12,16 +12,14 @@ patchRecordMethods('NotificationGroup', {
         if (this.notification_type !== 'snail') {
             return this._super(...arguments);
         }
-        this.env.bus.trigger('do-action', {
-            action: {
-                name: this.env._t("Snailmail Failures"),
-                type: 'ir.actions.act_window',
-                view_mode: 'kanban,list,form',
-                views: [[false, 'kanban'], [false, 'list'], [false, 'form']],
-                target: 'current',
-                res_model: this.res_model,
-                domain: [['message_ids.snailmail_error', '=', true]],
-            },
+        this.env.services.action.doAction({
+            name: this.env._t("Snailmail Failures"),
+            type: 'ir.actions.act_window',
+            view_mode: 'kanban,list,form',
+            views: [[false, 'kanban'], [false, 'list'], [false, 'form']],
+            target: 'current',
+            res_model: this.res_model,
+            domain: [['message_ids.snailmail_error', '=', true]],
         });
         if (this.messaging.device.isSmall) {
             // messaging menu has a higher z-index than views so it must
diff --git a/addons/snailmail/static/tests/helpers/mock_server.js b/addons/snailmail/static/tests/helpers/mock_server.js
index aa804f6a67b..e42cfe1746b 100644
--- a/addons/snailmail/static/tests/helpers/mock_server.js
+++ b/addons/snailmail/static/tests/helpers/mock_server.js
@@ -1,8 +1,11 @@
 /** @odoo-module **/
 
-import MockServer from 'web.MockServer';
+import '@mail/../tests/helpers/mock_server'; // ensure mail overrides are applied first
 
-MockServer.include({
+import { patch } from "@web/core/utils/patch";
+import { MockServer } from "@web/../tests/helpers/mock_server";
+
+patch(MockServer.prototype, 'snailmail', {
     //--------------------------------------------------------------------------
     // Private
     //--------------------------------------------------------------------------
@@ -10,7 +13,7 @@ MockServer.include({
     /**
      * @override
      */
-    async _performRpc(route, args) {
+    async performRPC(route, args) {
         if (args.model === 'mail.message' && args.method === 'cancel_letter') {
             const ids = args.args[0];
             return this._mockMailMessageCancelLetter(ids);
@@ -19,6 +22,10 @@ MockServer.include({
             const ids = args.args[0];
             return this._mockMailMessageSendLetter(ids);
         }
+        if (args.method === 'get_credits_url') {
+            // random value returned in order for the mock server to know that this route is implemented.
+            return true;
+        }
         return this._super(...arguments);
     },
 
@@ -34,6 +41,8 @@ MockServer.include({
      */
     _mockMailMessageCancelLetter(ids) {
         // TODO implement this mock and improve related tests (task-2300496)
+        // random value returned in order for the mock server to know that this route is implemented.
+        return true;
     },
     /**
      * Simulates `send_letter` on `mail.message`.
@@ -43,5 +52,7 @@ MockServer.include({
      */
     _mockMailMessageSendLetter(ids) {
         // TODO implement this mock and improve related tests (task-2300496)
+        // random value returned in order for the mock server to know that this route is implemented.
+        return true;
     },
 });
diff --git a/addons/snailmail/static/tests/qunit_suite_tests/components/message_tests.js b/addons/snailmail/static/tests/qunit_suite_tests/components/message_tests.js
index 735d5a32d6c..1de8671bdfc 100644
--- a/addons/snailmail/static/tests/qunit_suite_tests/components/message_tests.js
+++ b/addons/snailmail/static/tests/qunit_suite_tests/components/message_tests.js
@@ -7,7 +7,7 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('snailmail', {}, function () {
 QUnit.module('components', {}, async function() {
@@ -274,7 +274,6 @@ QUnit.test('No Price Available', async function (assert) {
             if (args.method === 'cancel_letter' && args.model === 'mail.message' && args.args[0][0] === mailMessageId1) {
                 assert.step(args.method);
             }
-            return this._super(...arguments);
         },
     });
     const threadViewer = messaging.models['ThreadViewer'].create({
@@ -368,7 +367,6 @@ QUnit.test('Credit Error', async function (assert) {
             if (args.method === 'send_letter' && args.model === 'mail.message' && args.args[0][0] === mailMessageId1) {
                 assert.step(args.method);
             }
-            return this._super(...arguments);
         },
     });
     const threadViewer = messaging.models['ThreadViewer'].create({
@@ -467,7 +465,6 @@ QUnit.test('Trial Error', async function (assert) {
             if (args.method === 'send_letter' && args.model === 'mail.message' && args.args[0][0] === mailMessageId1) {
                 assert.step(args.method);
             }
-            return this._super(...arguments);
         },
     });
     const threadViewer = messaging.models['ThreadViewer'].create({
@@ -561,8 +558,9 @@ QUnit.test('Format Error', async function (assert) {
         notification_type: 'snail',
         res_partner_id: resPartnerId1,
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action, options }) => {
+    const { createThreadViewComponent, env, messaging } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('do_action');
             assert.strictEqual(
                 action,
@@ -574,8 +572,8 @@ QUnit.test('Format Error', async function (assert) {
                 mailMessageId1,
                 "action should have correct message id"
             );
+        },
     });
-    const { createThreadViewComponent, messaging } = await start({ env: { bus } });
     const threadViewer = messaging.models['ThreadViewer'].create({
         hasThreadView: true,
         qunitTest: insertAndReplace(),
@@ -636,8 +634,10 @@ QUnit.test('Missing Required Fields', async function (assert) {
     const snailMailLetterId1 = pyEnv['snailmail.letter'].create({
         message_id: mailMessageId1,
     });
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action, options }) => {
+
+    const { createThreadViewComponent, env, messaging } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('do_action');
             assert.strictEqual(
                 action,
@@ -649,10 +649,7 @@ QUnit.test('Missing Required Fields', async function (assert) {
                 snailMailLetterId1,
                 "action should have correct letter id"
             );
-    });
-
-    const { createThreadViewComponent, messaging } = await start({
-        env: { bus },
+        },
     });
     const threadViewer = messaging.models['ThreadViewer'].create({
         hasThreadView: true,
diff --git a/addons/snailmail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js b/addons/snailmail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
index 25b07430c26..2c9cc8c9ba9 100644
--- a/addons/snailmail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
+++ b/addons/snailmail/static/tests/qunit_suite_tests/components/notification_list_notification_group_tests.js
@@ -2,7 +2,7 @@
 
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 
-import Bus from 'web.Bus';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 QUnit.module('snailmail', {}, function () {
 QUnit.module('components', {}, function () {
@@ -189,8 +189,9 @@ QUnit.test('grouped notifications by document model', async function (assert) {
             notification_type: 'snail', // expected failure type for snailmail message
         },
     ]);
-    const bus = new Bus();
-    bus.on('do-action', null, ({ action }) => {
+    const { createNotificationListComponent, env } = await start();
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             assert.step('do_action');
             assert.strictEqual(
                 action.name,
@@ -227,9 +228,8 @@ QUnit.test('grouped notifications by document model', async function (assert) {
                 JSON.stringify([['message_ids.snailmail_error', '=', true]]),
                 "action should have 'message_has_sms_error' as domain"
             );
+        },
     });
-
-    const { createNotificationListComponent } = await start({ env: { bus } });
     await createNotificationListComponent();
 
     assert.containsOnce(
diff --git a/addons/test_mail/static/tests/activity_tests.js b/addons/test_mail/static/tests/activity_tests.js
index a698a8e0fb3..d163fe8671d 100644
--- a/addons/test_mail/static/tests/activity_tests.js
+++ b/addons/test_mail/static/tests/activity_tests.js
@@ -1,11 +1,9 @@
 /** @odoo-module **/
 
 import ActivityRenderer from '@mail/js/views/activity/activity_renderer';
-import ActivityView from '@mail/js/views/activity/activity_view';
 import { start, startServer } from '@mail/../tests/helpers/test_utils';
 
 import testUtils from 'web.test_utils';
-import domUtils from 'web.dom';
 
 import { legacyExtraNextTick, patchWithCleanup, click } from "@web/../tests/helpers/utils";
 import { doAction } from "@web/../tests/webclient/helpers";
@@ -62,7 +60,7 @@ QUnit.module('activity view', {
             { name: 'Office planning', activity_ids: [mailActivityIds[1], mailActivityIds[2]] },
         ]);
         serverData = {
-            views : {
+            views: {
                 'mail.test.activity,false,activity':
                     '<activity string="MailTestActivity">' +
                             '<templates>' +
@@ -71,9 +69,6 @@ QUnit.module('activity view', {
                                 '</div>' +
                             '</templates>' +
                     '</activity>',
-                'mail.activity,false,form': '<form/>',
-                'mail.test.activity,false,form': '<form/>',
-                'mail.test.activity,false,search': '<search/>',
             },
         };
     }
@@ -87,8 +82,17 @@ QUnit.test('activity view: simple activity rendering', async function (assert) {
     assert.expect(14);
     const mailTestActivityIds = pyEnv['mail.test.activity'].search([]);
     const mailActivityTypeIds = pyEnv['mail.activity.type'].search([]);
-    const actionServiceInterceptor = event => {
-            assert.deepEqual(event.data.action, {
+
+    const { env, openView } = await start({
+        serverData,
+    });
+    await openView({
+        res_model: "mail.test.activity",
+        views: [[false, "activity"]],
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
+            assert.deepEqual(action, {
                 context: {
                     default_res_id: mailTestActivityIds[1],
                     default_res_model: "mail.test.activity",
@@ -103,25 +107,12 @@ QUnit.test('activity view: simple activity rendering', async function (assert) {
                 views: [[false, "form"]]
             },
             "should do a do_action with correct parameters");
-            event.data.options.on_close();
-    };
-    await start({
-        View: ActivityView,
-        hasView: true,
-        model: 'mail.test.activity',
-        arch: '<activity string="Task">' +
-                    '<templates>' +
-                        '<div t-name="activity-box">' +
-                            '<field name="name"/>' +
-                        '</div>' +
-                    '</templates>' +
-            '</activity>',
-        intercepts: {
-            do_action: actionServiceInterceptor,
+            options.onClose();
+            return Promise.resolve();
         },
     });
-    const $activity = $(document);
 
+    const $activity = $(document.querySelector('.o_activity_view'));
     assert.containsOnce($activity, 'table',
         'should have a table');
     var $th1 = $activity.find('table thead tr:first th:nth-child(2)');
@@ -158,20 +149,14 @@ QUnit.test('activity view: simple activity rendering', async function (assert) {
 QUnit.test('activity view: no content rendering', async function (assert) {
     assert.expect(2);
 
+    const { openView, pyEnv } = await start({
+        serverData,
+    });
     // reset incompatible setup
     pyEnv['mail.activity.type'].unlink(pyEnv['mail.activity.type'].search([]));
-
-    await start({
-        hasView: true,
-        View: ActivityView,
-        model: 'mail.test.activity',
-        arch: '<activity string="Task">' +
-                '<templates>' +
-                    '<div t-name="activity-box">' +
-                        '<field name="name"/>' +
-                    '</div>' +
-                '</templates>' +
-            '</activity>',
+    await openView({
+        res_model: "mail.test.activity",
+        views: [[false, "activity"]],
     });
     const $activity = $(document);
 
@@ -187,25 +172,19 @@ QUnit.test('activity view: batch send mail on activity', async function (assert)
 
     const mailTestActivityIds = pyEnv['mail.test.activity'].search([]);
     const mailTemplateIds = pyEnv['mail.template'].search([]);
-    await start({
-        hasView: true,
-        View: ActivityView,
-        model: 'mail.test.activity',
-        arch: '<activity string="Task">' +
-                '<templates>' +
-                    '<div t-name="activity-box">' +
-                        '<field name="name"/>' +
-                    '</div>' +
-                '</templates>' +
-            '</activity>',
+    const { openView } = await start({
+        serverData,
         mockRPC: function(route, args) {
-            if (args.method === 'activity_send_mail'){
+            if (args.method === 'activity_send_mail') {
                 assert.step(JSON.stringify(args.args));
-                return Promise.resolve();
+                return Promise.resolve(true);
             }
-            return this._super.apply(this, arguments);
         },
     });
+    await openView({
+        res_model: "mail.test.activity",
+        views: [[false, "activity"]],
+    });
     const $activity = $(document);
     assert.notOk($activity.find('table thead tr:first th:nth-child(2) span:nth-child(2) .dropdown-menu.show').length,
         'dropdown shouldn\'t be displayed');
@@ -232,8 +211,33 @@ QUnit.test('activity view: activity widget', async function (assert) {
     const mailActivityTypeIds = pyEnv['mail.activity.type'].search([]);
     const [mailTestActivityId2] = pyEnv['mail.test.activity'].search([['name', '=', 'Office planning']]);
     const [mailTemplateId1] = pyEnv['mail.template'].search([['name', '=', 'Template1']]);
-    const actionServiceInterceptor = ev => {
-            var action = ev.data.action;
+    const { env, openView } = await start({
+        mockRPC: function (route, args) {
+            if (args.method === 'activity_send_mail') {
+                assert.deepEqual([[mailTestActivityId2], mailTemplateId1], args.args, "Should send template related to mailTestActivity2");
+                assert.step('activity_send_mail');
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
+            }
+            if (args.method === 'action_feedback_schedule_next') {
+                assert.deepEqual(
+                    [pyEnv['mail.activity'].search([['state', '=', 'overdue']])],
+                    args.args,
+                    "Should execute action_feedback_schedule_next only on the overude activity"
+                );
+                assert.equal(args.kwargs.feedback, "feedback2");
+                assert.step('action_feedback_schedule_next');
+                return Promise.resolve({ serverGeneratedAction: true });
+            }
+        },
+        serverData,
+    });
+    await openView({
+        res_model: 'mail.test.activity',
+        views: [[false, 'activity']],
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action) {
             if (action.serverGeneratedAction) {
                 assert.step('serverGeneratedAction');
             } else if (action.res_model === 'mail.compose.message') {
@@ -255,38 +259,10 @@ QUnit.test('activity view: activity widget', async function (assert) {
             } else {
                 assert.step("Unexpected action");
             }
-    };
-    const params = {
-        hasView: true,
-        View: ActivityView,
-        model: 'mail.test.activity',
-        arch: '<activity string="Task">' +
-                '<templates>' +
-                    '<div t-name="activity-box">' +
-                        '<field name="name"/>' +
-                    '</div>' +
-                '</templates>'+
-            '</activity>',
-        mockRPC: function(route, args) {
-            if (args.method === 'activity_send_mail'){
-                assert.deepEqual([[mailTestActivityId2],mailTemplateId1],args.args, "Should send template 8 on record 30");
-                assert.step('activity_send_mail');
-                return Promise.resolve();
-            }
-            if (args.method === 'action_feedback_schedule_next'){
-                assert.deepEqual([[3]],args.args, "Should execute action_feedback_schedule_next on activity 3 only ");
-                assert.equal(args.kwargs.feedback, "feedback2");
-                assert.step('action_feedback_schedule_next');
-                return Promise.resolve({serverGeneratedAction: true});
-            }
-            return this._super.apply(this, arguments);
+            return Promise.resolve();
         },
-        intercepts: {
-            do_action: actionServiceInterceptor,
-        },
-    };
+    });
 
-    await start(params);
     const activity = $(document);
     var today = activity.find('table tbody tr:first td:nth-child(2).today');
     var dropdown = today.find('.dropdown-menu.o_activity');
@@ -319,7 +295,8 @@ QUnit.test('activity view: activity widget', async function (assert) {
         "do_action_activity",
         "action_feedback_schedule_next",
         "serverGeneratedAction"
-        ]);
+    ]);
+
 });
 
 QUnit.test("activity view: no group_by_menu and no comparison_menu", async function (assert) {
@@ -347,7 +324,7 @@ QUnit.test("activity view: no group_by_menu and no comparison_menu", async funct
 
     patchWithCleanup(session.user_context, { lang: "zz_ZZ" });
 
-    const { widget: webClient } = await start({ hasWebClient: true, serverData, mockRPC, legacyParams: {withLegacyMockServer: true}});
+    const { webClient } = await start({ serverData, mockRPC });
 
     await doAction(webClient, 1);
 
@@ -373,7 +350,20 @@ QUnit.test('activity view: search more to schedule an activity for a record of a
     Object.assign(serverData.views, {
         'mail.test.activity,false,list': '<tree string="MailTestActivity"><field name="name"/></tree>',
     });
-    const actionServiceInterceptor = ev => {
+    const { env, openView } = await start({
+        mockRPC(route, args) {
+            if (args.method === 'name_search') {
+                args.kwargs.name = "MailTestActivity";
+            }
+        },
+        serverData,
+    });
+    await openView({
+        res_model: 'mail.test.activity',
+        views: [[false, 'activity']],
+    });
+    patchWithCleanup(env.services.action, {
+        doAction(action, options) {
             assert.step('doAction');
             var expectedAction = {
                 context: {
@@ -388,43 +378,20 @@ QUnit.test('activity view: search more to schedule an activity for a record of a
                 view_mode: "form",
                 views: [[false, "form"]],
             };
-            assert.deepEqual(ev.data.action, expectedAction,
+            assert.deepEqual(action, expectedAction,
                 "should execute an action with correct params");
-            ev.data.options.on_close();
-    };
-    await start({
-        hasView: true,
-        View: ActivityView,
-        model: 'mail.test.activity',
-        arch: '<activity string="Task">' +
-                '<templates>' +
-                    '<div t-name="activity-box">' +
-                        '<field name="name"/>' +
-                    '</div>' +
-                '</templates>' +
-            '</activity>',
-        archs: {
-            "mail.test.activity,false,list": '<tree string="Task"><field name="name"/></tree>',
-            "mail.test.activity,false,search": '<search></search>',
-        },
-        mockRPC: function(route, args) {
-            if (args.method === 'name_search') {
-                args.kwargs.name = "Task";
-            }
-            return this._super.apply(this, arguments);
-        },
-        intercepts: {
-            do_action: actionServiceInterceptor,
+            options.onClose();
+            return Promise.resolve();
         },
     });
-    const $activity = $(document);
 
-    assert.containsOnce($activity, 'table tfoot tr .o_record_selector',
+    const activity = $(document);
+    assert.containsOnce(activity, 'table tfoot tr .o_record_selector',
         'should contain search more selector to choose the record to schedule an activity for it');
-    await testUtils.dom.click($activity.find('table tfoot tr .o_record_selector'));
+    await testUtils.dom.click(activity.find('table tfoot tr .o_record_selector'));
     // search create dialog
     var $modal = $('.modal-lg');
-    assert.strictEqual($modal.find('.o_data_row').length, 3, "all tasks should be available to select");
+    assert.strictEqual($modal.find('.o_data_row').length, 3, "all mail.test.activity should be available to select");
     // select a record to schedule an activity for it (this triggers a do_action)
     testUtils.dom.click($modal.find('.o_data_row:last'));
     assert.verifySteps(['doAction']);
@@ -459,7 +426,7 @@ QUnit.test("Activity view: discard an activity creation dialog", async function
         }
     };
 
-    const { widget: webClient } = await start({ hasWebClient: true, serverData, mockRPC, legacyParams: {withLegacyMockServer: true} });
+    const { webClient } = await start({ serverData, mockRPC });
     await doAction(webClient, 1);
 
     await testUtils.dom.click(
@@ -503,7 +470,7 @@ QUnit.test('Activity view: many2one_avatar_user widget in activity view', async
         }
     };
 
-    const { widget: webClient } = await start({ hasWebClient: true, serverData, legacyParams: { withLegacyMockServer: true } });
+    const { webClient } = await start({ serverData });
     await doAction(webClient, 1);
 
     await legacyExtraNextTick();
@@ -517,20 +484,6 @@ QUnit.test('Activity view: many2one_avatar_user widget in activity view', async
 QUnit.test("Activity view: on_destroy_callback doesn't crash", async function (assert) {
     assert.expect(3);
 
-    const params = {
-        hasView: true,
-        View: ActivityView,
-        model: 'mail.test.activity',
-        data: this.data,
-        arch: `<activity string="Task">
-                <templates>
-                    <div t-name="activity-box">
-                        <field name="name"/>
-                    </div>
-                </templates>
-            </activity>`,
-    };
-
     patchWithCleanup(ActivityRenderer.prototype, {
         setup() {
             this._super();
@@ -543,8 +496,18 @@ QUnit.test("Activity view: on_destroy_callback doesn't crash", async function (a
         }
     });
 
-    const { widget: activity } = await start(params);
-    domUtils.detach([{ widget: activity }]);
+    const { openView } = await start({
+        serverData,
+    });
+    await openView({
+        res_model: 'mail.test.activity',
+        views: [[false, 'activity']],
+    });
+    // force the unmounting of the activity view by opening another one
+    await openView({
+        res_model: 'mail.test.activity',
+        views: [[false, 'form']],
+    });
 
     assert.verifySteps([
         'mounted',
@@ -567,7 +530,7 @@ QUnit.test("Schedule activity dialog uses the same search view as activity view"
         }
     }
 
-    const { widget: webClient } = await start({ hasWebClient: true, serverData, mockRPC, legacyParams: {withLegacyMockServer: true} });
+    const { webClient } = await start({ serverData, mockRPC });
 
     // open an activity view (with default search arch)
     await doAction(webClient, {
@@ -606,7 +569,7 @@ QUnit.test("Schedule activity dialog uses the same search view as activity view"
 
     assert.verifySteps([
         '[[false,"list"],[1,"search"]]',
-    ])
+    ]);
 });
 
 QUnit.test('Activity view: apply progressbar filter', async function (assert) {
@@ -622,7 +585,7 @@ QUnit.test('Activity view: apply progressbar filter', async function (assert) {
         }
     };
 
-    const { widget: webClient } = await start({ hasWebClient:true, serverData, legacyParams: { withLegacyMockServer: true } });
+    const { webClient } = await start({ serverData });
 
     await doAction(webClient, 1);
 
diff --git a/addons/test_mail/static/tests/systray_activity_menu_tests.js b/addons/test_mail/static/tests/systray_activity_menu_tests.js
index 00690df9cd6..102ead63702 100644
--- a/addons/test_mail/static/tests/systray_activity_menu_tests.js
+++ b/addons/test_mail/static/tests/systray_activity_menu_tests.js
@@ -40,7 +40,6 @@ QUnit.test('activity menu widget: menu with no records', async function (assert)
     legacySystrayItems.push(ActivityMenu);
     registerCleanup(() => legacySystrayItems.pop());
     await start({
-        hasWebClient: true,
         mockRPC: function (route, args) {
             if (args.method === 'systray_get_activities') {
                 return Promise.resolve([]);
@@ -56,9 +55,7 @@ QUnit.test('activity menu widget: activity menu with 2 models', async function (
 
     legacySystrayItems.push(ActivityMenu);
     registerCleanup(() => legacySystrayItems.pop());
-    const { wowlEnv: env } = await start({
-        hasWebClient: true,
-    });
+    const { env } = await start();
 
     await testUtils.nextTick();
     assert.containsOnce(document.body, '.o_mail_systray_item', 'should contain an instance of widget');
@@ -113,9 +110,7 @@ QUnit.test('activity menu widget: activity view icon', async function (assert) {
     patchWithCleanup(session, { uid: 10 });
     legacySystrayItems.push(ActivityMenu);
     registerCleanup(() => legacySystrayItems.pop());
-    const { wowlEnv: env } = await start({
-        hasWebClient: true,
-    });
+    const { env } = await start();
     await testUtils.nextTick();
     assert.containsN(document.body, '.o_mail_activity_action', 2,
                        "widget should have 2 activity view icons");
@@ -167,9 +162,7 @@ QUnit.test('activity menu widget: close on messaging menu click', async function
 
     legacySystrayItems.push(ActivityMenu);
     registerCleanup(() => legacySystrayItems.pop());
-    const { click, createMessagingMenuComponent } = await start({
-        hasWebClient: true,
-    });
+    const { click, createMessagingMenuComponent } = await start();
     await createMessagingMenuComponent();
     await testUtils.nextTick();
 
diff --git a/addons/test_mail/static/tests/tracking_value_tests.js b/addons/test_mail/static/tests/tracking_value_tests.js
index 1fbc4bef69e..68b9ab5ac35 100644
--- a/addons/test_mail/static/tests/tracking_value_tests.js
+++ b/addons/test_mail/static/tests/tracking_value_tests.js
@@ -5,39 +5,54 @@ import {
     startServer,
 } from '@mail/../tests/helpers/test_utils';
 
-import FormView from 'web.FormView';
+import { patchWithCleanup } from "@web/../tests/helpers/utils";
+
+import session from 'web.session';
 import testUtils from 'web.test_utils';
 
 QUnit.module('test_mail', {}, function () {
 QUnit.module('tracking_value_tests.js', {
     beforeEach() {
-        this.start = async params => {
-            return start({
-                arch: `<form>
-                            <sheet>
-                                <field name="boolean_field"/>
-                                <field name="char_field"/>
-                                <field name="date_field"/>
-                                <field name="datetime_field"/>
-                                <field name="float_field"/>
-                                <field name="integer_field"/>
-                                <field name="monetary_field"/>
-                                <field name="many2one_field_id"/>
-                                <field name="selection_field"/>
-                                <field name="text_field"/>
-                            </sheet>
-                            <div class="oe_chatter">
-                                <field name="message_ids"/>
-                            </div>
-                        </form>`,
-                archs: { 'mail.message,false,list': '<tree/>' },
-                hasView: true,
-                model: 'mail.test.track.all',
-                View: FormView,
-                viewOptions: { mode: 'edit' },
-                ...params,
-            });
+        const views = {
+            'mail.test.track.all,false,form':
+                `<form>
+                    <sheet>
+                        <field name="boolean_field"/>
+                        <field name="char_field"/>
+                        <field name="date_field"/>
+                        <field name="datetime_field"/>
+                        <field name="float_field"/>
+                        <field name="integer_field"/>
+                        <field name="monetary_field"/>
+                        <field name="many2one_field_id"/>
+                        <field name="selection_field"/>
+                        <field name="text_field"/>
+                    </sheet>
+                    <div class="oe_chatter">
+                        <field name="message_ids"/>
+                    </div>
+                </form>`,
         };
+        this.start = async ({ res_id }) => {
+            const { openView, ...remainder } = await start({
+                serverData: { views },
+            });
+            await openView(
+                {
+                    res_model: 'mail.test.track.all',
+                    res_id,
+                    views: [[false, 'form']],
+                },
+                { mode: 'edit' }
+            );
+            return remainder;
+        };
+
+        patchWithCleanup(session, {
+            getTZOffset() {
+                return 0;
+            },
+        });
     },
 });
 
diff --git a/addons/web/__manifest__.py b/addons/web/__manifest__.py
index 009622c79e0..7441e83839a 100644
--- a/addons/web/__manifest__.py
+++ b/addons/web/__manifest__.py
@@ -506,6 +506,7 @@ This module provides the core of the Odoo Web Client.
         'web.qunit_suite_tests': [
             'base/static/tests/base_settings_tests.js',
             'web/static/tests/env_tests.js',
+            'web/static/tests/mock_relational_fields_tests.js',
             'web/static/tests/core/**/*.js',
             'web/static/tests/fields/**/*.js',
             'web/static/tests/search/**/*.js',
diff --git a/addons/web/static/src/core/browser/browser.js b/addons/web/static/src/core/browser/browser.js
index d587af041fa..0223cc526d6 100644
--- a/addons/web/static/src/core/browser/browser.js
+++ b/addons/web/static/src/core/browser/browser.js
@@ -38,6 +38,8 @@ export const browser = {
     localStorage,
     sessionStorage,
     fetch: window.fetch.bind(window),
+    innerHeight: window.innerHeight,
+    innerWidth: window.innerWidth,
 };
 
 Object.defineProperty(browser, "location", {
diff --git a/addons/web/static/tests/helpers/mock_server.js b/addons/web/static/tests/helpers/mock_server.js
index b88018538e0..2876df50ad8 100644
--- a/addons/web/static/tests/helpers/mock_server.js
+++ b/addons/web/static/tests/helpers/mock_server.js
@@ -32,6 +32,10 @@ function traverseElementTree(tree, cb) {
 
 export class MockServer {
     constructor(data, options = {}) {
+        this.init(data, options);
+    }
+
+    init(data, options) {
         this.models = data.models || {};
         this.actions = data.actions || {};
         this.menus = data.menus || null;
@@ -62,6 +66,15 @@ export class MockServer {
             model.onchanges = model.onchanges || {};
             model.methods = model.methods || {};
         });
+
+        // fill relational fields' inverse.
+        for (const modelName in this.models) {
+            const records = this.models[modelName].records
+            if (!Array.isArray(this.models[modelName].records)) {
+                continue;
+            }
+            records.forEach(record => this.updateComodelRelationalFields(modelName, record));
+        }
     }
 
     /**
@@ -478,6 +491,8 @@ export class MockServer {
                 return this.mockSearchPanelSelectMultiRange(args.model, args.args, args.kwargs);
             case "search_read":
                 return this.mockSearchRead(args.model, args.args, args.kwargs);
+            case "unlink":
+                return this.mockUnlink(args.model, args.args);
             case "web_search_read":
                 return this.mockWebSearchRead(args.model, args.args, args.kwargs);
             case "read_group":
@@ -505,6 +520,7 @@ export class MockServer {
         model.records.push(record);
         this.applyDefaults(model, values);
         this.writeRecord(modelName, values, id);
+        this.updateComodelRelationalFields(modelName, record);
         return id;
     }
 
@@ -998,6 +1014,32 @@ export class MockServer {
         return readGroupResult;
     }
 
+    mockUnlink(modelName, args) {
+        var ids = args[0];
+        if (!Array.isArray(ids)) {
+            ids = [ids];
+        }
+        this.models[modelName].records = this.models[modelName].records.filter(record => !ids.includes(record.id));
+
+        // update value of relationnal fields pointing to the deleted records
+        _.each(this.models, function (d) {
+            var relatedFields = _.pick(d.fields, function (field) {
+                return field.relation === modelName;
+            });
+            _.each(Object.keys(relatedFields), function (relatedField) {
+                _.each(d.records, function (record) {
+                    if (Array.isArray(record[relatedField])) {
+                        record[relatedField] = _.difference(record[relatedField], ids);
+                    } else if (ids.includes(record[relatedField])) {
+                        record[relatedField] = false;
+                    }
+                });
+            });
+        });
+
+         return { result: true };
+    }
+
     mockWebReadGroup(modelName, kwargs) {
         const groups = this.mockReadGroup(modelName, kwargs);
         if (kwargs.expand && kwargs.groupby.length === 1) {
@@ -1637,13 +1679,82 @@ export class MockServer {
     }
 
     mockWrite(modelName, args) {
-        args[0].forEach((id) => this.writeRecord(modelName, args[1], id));
+        args[0].forEach((id) => {
+            const [originalRecord] = this.mockSearchRead(modelName, [[['id', '=', id]]], {});
+            this.writeRecord(modelName, args[1], id);
+            const updatedRecord = this.models[modelName].records.find(record => record.id === id);
+            this.updateComodelRelationalFields(modelName, updatedRecord, originalRecord);
+        });
         return true;
     }
 
     //////////////////////////////////////////////////////////////////////////////
     // Private
     //////////////////////////////////////////////////////////////////////////////
+
+    /**
+     * Fill all inverse fields of the relational fields present in the record
+     * to be created/updated.
+     *
+     * @param {string} modelName
+     * @param {Object} record record that have been created/updated.
+     * @param {Object|undefined} originalRecord record before update.
+     */
+    updateComodelRelationalFields(modelName, record, originalRecord) {
+        for (const fname in record) {
+            const field = this.models[modelName].fields[fname];
+            const comodelName = field.relation || record[field['model_name_ref_fname']];
+            const inverseFieldName = field['inverse_fname_by_model_name'] && field['inverse_fname_by_model_name'][comodelName];
+            if (!inverseFieldName) {
+                // field has no inverse, skip it.
+                continue;
+            }
+            const relatedRecordIds = Array.isArray(record[fname]) ? record[fname] : [record[fname]];
+            // we only want to set a value for comodel inverse field if the model field has a value.
+            if (record[fname]) {
+                for (const relatedRecordId of relatedRecordIds) {
+                    let inverseFieldNewValue = record.id;
+                    const relatedRecord = this.models[comodelName].records.find(record => record.id === relatedRecordId);
+                    const relatedFieldValue = relatedRecord && relatedRecord[inverseFieldName];
+                    if (
+                        relatedFieldValue === undefined ||
+                        relatedFieldValue === record.id ||
+                        field.type !== 'one2many' && relatedFieldValue.includes(record.id)
+                    ) {
+                        // related record does not exist or the related value is already up to date.
+                        continue;
+                    }
+                    if (Array.isArray(relatedFieldValue)) {
+                        inverseFieldNewValue = [...relatedFieldValue, record.id];
+                    }
+                    this.writeRecord(comodelName, { [inverseFieldName]: inverseFieldNewValue }, relatedRecordId);
+                }
+            } else if (field.type === 'many2one_reference') {
+                // we need to clean the many2one_field as well.
+                const comodel_inverse_field = this.models[comodelName].fields[inverseFieldName];
+                const model_many2one_field = comodel_inverse_field['inverse_fname_by_model_name'][modelName];
+                this.writeRecord(modelName, { [model_many2one_field]: false }, record.id);
+            }
+            // it's an update, get the records that were originally referenced but are not
+            // anymore and update their relational fields.
+            if (originalRecord) {
+                const originalRecordIds = Array.isArray(originalRecord[fname]) ? originalRecord[fname] : [originalRecord[fname]];
+                // search read returns [id, name], let's ensure the removedRecordIds are integers.
+                const removedRecordIds = originalRecordIds.filter(recordId => Number.isInteger(recordId) && !relatedRecordIds.includes(recordId));
+                for (const removedRecordId of removedRecordIds) {
+                    const removedRecord = this.models[comodelName].records.find(record => record.id === removedRecordId);
+                    if (!removedRecord) {
+                        continue;
+                    }
+                    let inverseFieldNewValue = false;
+                    if (Array.isArray(removedRecord[inverseFieldName])) {
+                        inverseFieldNewValue = removedRecord[inverseFieldName].filter(id => id !== record.id);
+                    }
+                    this.writeRecord(comodelName, { [inverseFieldName]: inverseFieldNewValue }, removedRecordId);
+                }
+            }
+        }
+    }
     evaluateDomain(domain, record) {
         return new Domain(domain).contains(record);
     }
@@ -1841,7 +1952,12 @@ export class MockServer {
                 for (const command of value || []) {
                     if (command[0] === 0) {
                         // CREATE
-                        const newId = this.mockCreate(field.relation, command[2]);
+                        const inverseData = command[2]; // write in place instead of copy, because some tests rely on the object given being updated
+                        const inverseFieldName = field.inverse_fname_by_model_name && field.inverse_fname_by_model_name[field.relation];
+                        if (inverseFieldName) {
+                            inverseData[inverseFieldName] = id;
+                        }
+                        const newId = this.mockCreate(field.relation, inverseData);
                         ids.push(newId);
                     } else if (command[0] === 1) {
                         // UPDATE
diff --git a/addons/web/static/tests/helpers/mock_services.js b/addons/web/static/tests/helpers/mock_services.js
index b697ff3e429..06913a4c43f 100644
--- a/addons/web/static/tests/helpers/mock_services.js
+++ b/addons/web/static/tests/helpers/mock_services.js
@@ -120,9 +120,8 @@ export function makeMockXHR(response, sendCb, def) {
 
 export function makeMockFetch(mockRPC) {
     const _rpc = buildMockRPC(mockRPC);
-    return async (input) => {
+    return async (input, params) => {
         let route = typeof input === "string" ? input : input.url;
-        let params;
         if (route.includes("load_menus")) {
             const routeArray = route.split("/");
             params = {
diff --git a/addons/web/static/tests/mock_relational_fields_tests.js b/addons/web/static/tests/mock_relational_fields_tests.js
new file mode 100644
index 00000000000..2b4b8313099
--- /dev/null
+++ b/addons/web/static/tests/mock_relational_fields_tests.js
@@ -0,0 +1,135 @@
+/** @odoo-module **/
+
+import { MockServer } from "@web/../tests/helpers/mock_server";
+
+QUnit.module('web', {}, function () {
+QUnit.module('mock_relational_fields_tests.js', {
+    beforeEach() {
+        this.models = {
+            foo: {
+                fields: {
+                    one2many_field: { type: 'one2many', relation: 'bar', inverse_fname_by_model_name: { bar: 'many2one_field' } },
+                    many2one_field: { type: 'many2one', relation: 'bar', inverse_fname_by_model_name: { bar: 'one2many_field' } },
+                    many2many_field: { type: 'many2many', relation: 'bar', inverse_fname_by_model_name: { bar: 'many2many_field' } },
+                    many2one_reference: { type: 'many2one_reference', model_name_ref_fname: 'res_model', inverse_fname_by_model_name: { bar: 'one2many_field' } },
+                    res_model: { type: 'char' },
+
+                },
+                records: [],
+            },
+            bar: {
+                fields: {
+                    many2one_field: { type: 'many2one', relation: 'foo' },
+                    one2many_field: { type: 'one2many', relation: 'foo', inverse_fname_by_model_name: { foo: 'many2one_field' } },
+                    many2many_field: { type: 'many2many', relation: 'foo', inverse_fname_by_model_name: { foo: 'many2many_field' } },
+                },
+                records: [],
+            },
+        };
+    }
+});
+
+QUnit.test('many2one_ref should auto fill inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['foo'].records.push({
+        id: 2,
+        res_model: 'bar',
+        many2one_reference: 1,
+    });
+    const mockServer = new MockServer({ models: this.models });
+    assert.deepEqual([2], mockServer.models['bar'].records[0].one2many_field);
+
+    mockServer.mockUnlink('foo', [2]);
+    assert.deepEqual([], mockServer.models['bar'].records[0].one2many_field);
+});
+
+QUnit.test('many2one should auto fill inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['foo'].records.push({
+        id: 2,
+        many2one_field: 1,
+    });
+    const mockServer = new MockServer({ models: this.models });
+    assert.deepEqual([2], mockServer.models['bar'].records[0].one2many_field);
+
+    mockServer.mockUnlink('foo', [2]);
+    assert.deepEqual([], mockServer.models['bar'].records[0].one2many_field);
+});
+
+QUnit.test('one2many should auto fill inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['bar'].records.push({ id: 2 });
+    this.models['foo'].records.push({
+        id: 3,
+        one2many_field: [1, 2],
+    });
+    const mockServer = new MockServer({ models: this.models });
+    assert.strictEqual(3, mockServer.models['bar'].records[0].many2one_field);
+    assert.strictEqual(3, mockServer.models['bar'].records[1].many2one_field);
+
+    mockServer.mockUnlink('foo', [3]);
+    assert.strictEqual(false, mockServer.models['bar'].records[0].many2one_field);
+    assert.strictEqual(false, mockServer.models['bar'].records[1].many2one_field);
+});
+
+QUnit.test('many2many should auto fill inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['foo'].records.push({
+        id: 2,
+        many2many_field: [1],
+    });
+    const mockServer = new MockServer({ models: this.models });
+    assert.deepEqual([2], mockServer.models['bar'].records[0].many2many_field);
+
+    mockServer.mockUnlink('foo', [2]);
+    assert.deepEqual([], mockServer.models['bar'].records[0].many2many_field);
+});
+
+QUnit.test('one2many update should update inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['bar'].records.push({ id: 2 });
+    this.models['foo'].records.push({
+        id: 3,
+        one2many_field: [1, 2],
+    });
+    const mockServer = new MockServer({ models: this.models });
+    mockServer.mockWrite('foo', [[3], { one2many_field: [1] }]);
+    assert.strictEqual(3, mockServer.models['bar'].records[0].many2one_field);
+    assert.strictEqual(false, mockServer.models['bar'].records[1].many2one_field);
+});
+
+QUnit.test('many2many update should update inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['foo'].records.push({
+        id: 2,
+        many2many_field: [1],
+    });
+    const mockServer = new MockServer({ models: this.models });
+    mockServer.mockWrite('foo', [[2], { many2many_field: [] }]);
+    assert.deepEqual([], mockServer.models['bar'].records[0].many2many_field);
+});
+
+QUnit.test('many2one update should update inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['foo'].records.push({
+        id: 2,
+        many2one_field: 1,
+    });
+    const mockServer = new MockServer({ models: this.models });
+    mockServer.mockWrite('foo', [[2], { many2one_field: false }]);
+    assert.deepEqual([], mockServer.models['bar'].records[0].one2many_field);
+});
+
+QUnit.test('many2one_ref update should update inverse field', async function (assert) {
+    this.models['bar'].records.push({ id: 1 });
+    this.models['foo'].records.push({
+        id: 2,
+        res_model: 'bar',
+        many2one_reference: 1,
+    });
+    const mockServer = new MockServer({ models: this.models });
+    mockServer.mockWrite('foo', [[2], { many2one_reference: false }]);
+    assert.deepEqual([], mockServer.models['bar'].records[0].one2many_field);
+});
+
+});
diff --git a/addons/web/static/tests/webclient/helpers.js b/addons/web/static/tests/webclient/helpers.js
index 1c572300361..266b93726f8 100644
--- a/addons/web/static/tests/webclient/helpers.js
+++ b/addons/web/static/tests/webclient/helpers.js
@@ -194,6 +194,11 @@ export async function addLegacyMockEnvironment(env, legacyParams = {}) {
     const legacyActionManagerService = makeLegacyActionManagerService(legacyEnv);
     serviceRegistry.add("legacy_action_manager", legacyActionManagerService);
     serviceRegistry.add("legacy_notification", makeLegacyNotificationService(legacyEnv));
+    // deploy the legacyServices given in parameter in WowlEnv
+    const { legacyServicesToDeployInWowlEnv } = legacyParams;
+    for (const legacyServiceName in legacyServicesToDeployInWowlEnv) {
+        serviceRegistry.add(legacyServiceName, legacyServicesToDeployInWowlEnv[legacyServiceName]);
+    }
     // patch DebouncedField delay
     const debouncedField = basicFields.DebouncedField;
     const initialDebouncedVal = debouncedField.prototype.DEBOUNCE;
diff --git a/addons/website_livechat/static/tests/helpers/mock_server.js b/addons/website_livechat/static/tests/helpers/mock_server.js
index a184b131693..e00c4a36546 100644
--- a/addons/website_livechat/static/tests/helpers/mock_server.js
+++ b/addons/website_livechat/static/tests/helpers/mock_server.js
@@ -2,9 +2,19 @@
 
 import '@im_livechat/../tests/helpers/mock_server'; // ensure mail overrides are applied first
 
-import MockServer from 'web.MockServer';
+import { patch } from "@web/core/utils/patch";
+import { MockServer } from "@web/../tests/helpers/mock_server";
 
-MockServer.include({
+patch(MockServer.prototype, 'website_livechat', {
+    /**
+     * @override
+     */
+     async _performRPC(route, args) {
+        if (route === '/web/dataset/call_button') {
+            return this._mockCallButton(args);
+        }
+        return this._super(route, args);
+    },
     /**
      * Simulate a 'call_button' operation from a view.
      *
diff --git a/addons/website_livechat/static/tests/qunit_suite_tests/messaging_notification_handler_tests.js b/addons/website_livechat/static/tests/qunit_suite_tests/messaging_notification_handler_tests.js
index 155e84df8b7..8f37622d46c 100644
--- a/addons/website_livechat/static/tests/qunit_suite_tests/messaging_notification_handler_tests.js
+++ b/addons/website_livechat/static/tests/qunit_suite_tests/messaging_notification_handler_tests.js
@@ -5,9 +5,10 @@ import {
     start,
     startServer,
 } from '@mail/../tests/helpers/test_utils';
+import { ViewAdapter } from '@web/legacy/action_adapters';
+import { patchWithCleanup } from '@web/../tests/helpers/utils';
 
 import FormView from 'web.FormView';
-import { mock } from 'web.test_utils';
 
 QUnit.module('website_livechat', {}, function () {
 QUnit.module('messaging_notification_handler_tests.js');
@@ -19,31 +20,38 @@ QUnit.test('should open chat window on send chat request to website visitor', as
     const websiteVisitorId1 = pyEnv['website.visitor'].create({
         display_name: "Visitor #11",
     });
-    const { env, widget } = await start({
-        hasView: true,
-        // View params
-        View: FormView,
-        model: 'website.visitor',
-        arch: `
-            <form>
+    const views = {
+        'website.visitor,false,form':
+            `<form>
                 <header>
                     <button name="action_send_chat_request" string="Send chat request" class="btn btn-primary" type="button"/>
                 </header>
                 <field name="name"/>
-            </form>
-        `,
-        res_id: websiteVisitorId1,
+            </form>`,
+    };
+    const { openView } = await start({
+        serverData: { views },
+        View: FormView,
     });
-    mock.intercept(widget, 'execute_action', payload => {
-        env.services.rpc({
-            route: '/web/dataset/call_button',
-            params: {
-                args: [payload.data.env.resIDs],
-                kwargs: { context: payload.data.env.context },
-                method: payload.data.action_data.name,
-                model: payload.data.env.model,
+    await openView({
+        res_model: 'website.visitor',
+        res_id: websiteVisitorId1,
+        views: [[false, 'form']],
+    });
+    patchWithCleanup(ViewAdapter.prototype, {
+        _trigger_up: async function({ name, data }) {
+            if (name === 'execute_action') {
+                this.env.services.rpc({
+                    route: '/web/dataset/call_button',
+                    params: {
+                        args: [data.env.resIDs],
+                        kwargs: { context: data.env.context },
+                        method: data.action_data.name,
+                        model: data.env.model,
+                    }
+                });
             }
-        });
+        },
     });
 
     await afterNextRender(() =>
diff --git a/addons/website_slides/static/tests/qunit_suite_tests/components/activity_tests.js b/addons/website_slides/static/tests/qunit_suite_tests/components/activity_tests.js
index 9f168f9114b..7ab46259d18 100644
--- a/addons/website_slides/static/tests/qunit_suite_tests/components/activity_tests.js
+++ b/addons/website_slides/static/tests/qunit_suite_tests/components/activity_tests.js
@@ -26,8 +26,9 @@ QUnit.test('grant course access', async function (assert) {
                 assert.strictEqual(args.args[0][0], slideChannelId1);
                 assert.strictEqual(args.kwargs.partner_id, resPartnerId1);
                 assert.step('access_grant');
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({
@@ -62,8 +63,9 @@ QUnit.test('refuse course access', async function (assert) {
                 assert.strictEqual(args.args[0][0], slideChannelId1);
                 assert.strictEqual(args.kwargs.partner_id, resPartnerId1);
                 assert.step('access_refuse');
+                // random value returned in order for the mock server to know that this route is implemented.
+                return true;
             }
-            return this._super(...arguments);
         },
     });
     await createChatterContainerComponent({