[FIX] mail: resolve issue with discuss app not considered opened

`isOpen` is only written during mounted but it might happen that the discuss
record is not yet created when the component is mounted.

task-2632702

closes odoo/odoo#75655

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/components/discuss/discuss.js

@@ -2,6 +2,7 @@
 
 import { registerMessagingComponent } from '@mail/utils/messaging_component';
 import { link, unlink } from '@mail/model/model_field_command';
+import { useUpdate } from '@mail/component_hooks/use_update/use_update';
 
 const { Component } = owl;
 const { useRef } = owl.hooks;
@@ -24,28 +25,19 @@ export class Discuss extends Component {
         // bind since passed as props
         this._onMobileAddItemHeaderInputSelect = this._onMobileAddItemHeaderInputSelect.bind(this);
         this._onMobileAddItemHeaderInputSource = this._onMobileAddItemHeaderInputSource.bind(this);
+        useUpdate({ func: () => this._update() });
     }
 
-    mounted() {
+    _update() {
         if (!this.discuss) {
             return;
         }
         this.discuss.update({ isOpen: true });
         if (this.discuss.thread) {
             this.trigger('o-push-state-action-manager');
-        } else if (this.discuss.messaging.isInitialized) {
+        } else if (!this._activeThreadCache && this.discuss.messaging.isInitialized) {
             this.discuss.openInitThread();
         }
-        this._updateLocalStoreProps();
-    }
-
-    patched() {
-        if (!this.discuss) {
-            return;
-        }
-        if (this.discuss.thread) {
-            this.trigger('o-push-state-action-manager');
-        }
         if (
             this.discuss.thread &&
             this.discuss.thread === this.messaging.inbox &&

addons/mail/static/src/components/discuss/tests/discuss_tests.js

@@ -23,14 +23,16 @@ QUnit.module('discuss_tests.js', {
         beforeEach(this);
 
         this.start = async params => {
-            const { afterEvent, env, widget } = await start(Object.assign({}, params, {
+            const res = await start(Object.assign({}, params, {
                 autoOpenDiscuss: true,
                 data: this.data,
                 hasDiscuss: true,
             }));
+            const { afterEvent, env, widget } = res;
             this.afterEvent = afterEvent;
             this.env = env;
             this.widget = widget;
+            return res;
         };
     },
     afterEach() {
@@ -50,6 +52,34 @@ QUnit.test('messaging not created', async function (assert) {
     messagingBeforeCreationDeferred.resolve();
 });
 
+QUnit.test('discuss should be marked as opened if the component is already rendered and messaging becomes created afterwards', async function (assert) {
+    assert.expect(1);
+
+    const messagingBeforeCreationDeferred = makeTestPromise();
+    await this.start({
+        messagingBeforeCreationDeferred,
+        waitUntilMessagingCondition: 'none',
+    });
+
+    await afterNextRender(() => messagingBeforeCreationDeferred.resolve());
+    assert.ok(
+        this.messaging.discuss.isOpen,
+        "discuss should be marked as opened if the component is already rendered and messaging becomes created afterwards"
+    );
+});
+
+QUnit.test('discuss should be marked as closed when the component is unmounted', async function (assert) {
+    assert.expect(1);
+
+    const { widget } = await this.start();
+
+    await afterNextRender(() => widget.destroy());
+    assert.notOk(
+        this.messaging.discuss.isOpen,
+        "discuss should be marked as closed when the component is unmounted"
+    );
+});
+
 QUnit.test('messaging not initialized', async function (assert) {
     assert.expect(1);