[FIX] mail: receive message then delayed needaction notifications

Before this commit, when a user received a needaction notification
on a message already stored locally, it crashed with this error:

`TypeError: Cannot read property 'getThreadIDs' of undefined`

This is caused by `addMessage` returning a Promise not resolved with
the message when the message is not new. The returned promise should
always be resolved with the message, in order to be consistent.

closes odoo/odoo#35724

Signed-off-by: Martin Geubelle (mge) <mge@openerp.com>

addons/mail/static/src/js/services/mail_manager.js

@@ -85,7 +85,7 @@ var MailManager =  AbstractService.extend({
     addMessage: function (data, options) {
         options = options || {};
         var message = this.getMessage(data.id);
-        var prom = Promise.resolve();
+        var prom;
         if (!message) {
             prom = this._addNewMessage(data, options);
         } else {
@@ -95,6 +95,7 @@ var MailManager =  AbstractService.extend({
                 });
             }
             this._addMessageToThreads(message, options);
+            prom = Promise.resolve(message);
         }
         return prom;
     },

addons/mail/static/tests/discuss_tests.js

@@ -60,6 +60,7 @@ QUnit.module('Discuss', {
                         type: 'integer',
                     },
                 },
+                records: [],
             },
             'res.partner': {
                 fields: {
@@ -1491,5 +1492,69 @@ QUnit.test('custom-named DM conversation', async function (assert) {
     discuss.destroy();
 });
 
+QUnit.test('receive channel message notification then delayed needaction notification', async function (assert) {
+    assert.expect(3);
+
+    const message = {
+        author_id: [5, 'Demo User'],
+        body: '<p>test</p>',
+        channel_ids: [1],
+        id: 100,
+        model: 'mail.channel',
+        needaction: true,
+        needaction_partner_ids: [3],
+        res_id: 1,
+    };
+    this.data.initMessaging = {
+        channel_slots: {
+            channel_channel: [{
+                id: 1,
+                channel_type: 'channel',
+                name: "general",
+            }],
+        },
+    };
+
+    const discuss = await createDiscuss({
+        context: {},
+        params: {},
+        data: this.data,
+        services: this.services,
+        session: {
+            partner_id: 3
+        },
+    });
+
+    const $inbox = discuss.$('.o_mail_discuss_item[data-thread-id="mailbox_inbox"]');
+    assert.hasClass(
+        $inbox,
+        'o_active',
+        "'Inbox' should be the currently active thread");
+    assert.containsNone(
+        discuss,
+        '.o_thread_message',
+        "inbox should contain no messages initially");
+
+    // simulate new needaction message posted on channnel
+    this.data['mail.message'].records.push(message);
+    // simulate receiving channel notification
+    discuss.call('bus_service', 'trigger', 'notification', [
+        [['myDB', 'mail.channel', 1], message]
+    ]);
+    // short delay after receiving needaction notification
+    await testUtils.nextTick();
+    // simulate receiving needaction message notification after a short delay
+    discuss.call('bus_service', 'trigger', 'notification', [
+        [['myDB', 'ir.needaction', 3], message]
+    ]);
+    await testUtils.nextTick();
+    assert.containsOnce(
+        discuss,
+        '.o_thread_message',
+        "inbox should contain one message");
+
+    discuss.destroy();
+});
+
 });
 });