[FIX] mail: check not broken @ mention in discuss

Rev. on this commit: https://github.com/odoo/odoo/commit/02ec09cb1c3e2d7bc7968f40c18f2208d7f3f498

A consequence of the above commit is that @ mention were broken:
the dropup menu with partner propositions was not displaying when
the user typed the first characters to mention a user (e.g. by typing
"[at]demo" in order to show the proposed mention "[at]Demo User" in a dropup
menu).

This commit fixes the issue by reverting the logic of how mentions are provided
by the chat_manager, while removing some dead code.

note: [at] = @

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

@@ -352,7 +352,6 @@ var ChatManager =  AbstractService.extend({
      *              => list containing a list of members (cached by chat_manager)
      */
     getMentionPartnerSuggestions: function (channel) {
-        var self = this;
         if (!channel) {
             return this.mentionPartnerSuggestions;
         }
@@ -365,14 +364,7 @@ var ChatManager =  AbstractService.extend({
                     shadow: true
                 })
                 .then(function (members) {
-                    var suggestions = [];
-                    _.each(self.mentionPartnerSuggestions, function (partners) {
-                        suggestions.push(_.filter(partners, function (partner) {
-                            return !_.findWhere(members, { id: partner.id });
-                        }));
-                    });
-
-                    return [suggestions];
+                    return [members];
                 });
         }
         return channel.membersDeferred;

addons/mail/static/tests/discuss_tests.js

@@ -2,10 +2,17 @@ odoo.define('mail.discuss_test', function (require) {
 "use strict";
 
 var ChatManager = require('mail.ChatManager');
+var Composers = require('mail.composer');
 var mailTestUtils = require('mail.testUtils');
 
+var concurrency = require('web.concurrency');
+var testUtils = require('web.test_utils');
+
+var BasicComposer = Composers.BasicComposer;
 var createBusService = mailTestUtils.createBusService;
 var createDiscuss = mailTestUtils.createDiscuss;
+var patchWindowGetSelection = testUtils.patchWindowGetSelection;
+var unpatchWindowGetSelection = testUtils.unpatchWindowGetSelection;
 
 QUnit.module('mail', {}, function () {
 
@@ -55,5 +62,87 @@ QUnit.test('basic rendering', function (assert) {
     });
 });
 
+QUnit.test('@ mention in channel', function (assert) {
+    assert.expect(9);
+    var done = assert.async();
+
+    this.data.initMessaging = {
+        channel_slots: {
+            channel_channel: [{
+                id: 1,
+                channel_type: "channel",
+                name: "general",
+            }],
+        },
+    };
+
+    // Remove the mention throttle to speed up the test
+    var mentionThrottle = BasicComposer.prototype.MENTION_THROTTLE;
+    BasicComposer.prototype.MENTION_THROTTLE = 1;
+
+    var fetchListenersDef = $.Deferred();
+
+    createDiscuss({
+        id: 1,
+        context: {},
+        params: {},
+        data: this.data,
+        services: this.services,
+        mockRPC: function (route, args) {
+            if (args.method === 'channel_fetch_listeners') {
+                fetchListenersDef.resolve();
+                return $.when([ { id: 2, name: 'TestUser'} ]);
+            }
+            return this._super.apply(this, arguments);
+        },
+    })
+    .then(function (discuss) {
+        var $general = discuss.$('.o_mail_chat_sidebar')
+                        .find('.o_mail_chat_channel_item[data-channel-id=1]');
+        assert.strictEqual($general.length, 1,
+            "should have the channel item with id 1");
+        assert.strictEqual($general.attr('title'), 'general',
+            "should have the title 'general'");
+
+        // click on general
+        $general.click();
+        var $input = discuss.$('.o_composer_input').first();
+        assert.ok($input.length, "should display a composer input");
+
+        // Simulate '@' typed by user with mocked Window.getSelection
+        // Note: focus is needed in order to trigger rpc 'channel_fetch_listeners'
+        $input.focus();
+        $input.text("@");
+        patchWindowGetSelection();
+        $input.trigger('keyup');
+
+        fetchListenersDef
+            .then(concurrency.delay.bind(concurrency, 0))
+            .then(function () {
+                assert.strictEqual(discuss.$('.dropup.o_composer_mention_dropdown.open').length, 1,
+                "dropup menu for partner mentions should be open");
+
+                var $mentionProposition = discuss.$('.o_mention_proposition');
+                assert.strictEqual($mentionProposition.length, 1,
+                    "should display one partner mention proposition");
+                assert.strictEqual($mentionProposition.data('id'), 2,
+                    "partner mention should link to the correct partner id");
+                assert.strictEqual($mentionProposition.find('.o_mention_name').text(), "TestUser",
+                    "partner mention should display the correct partner name");
+
+                $mentionProposition.click();
+                assert.strictEqual(discuss.$('.o_mention_proposition').length, 0,
+                    "should not have any partner mention proposition after clicking on it");
+                assert.strictEqual($input.find('a').text() , "@TestUser",
+                    "should have the correct mention link in the composer input");
+
+                BasicComposer.prototype.MENTION_THROTTLE = mentionThrottle;
+                unpatchWindowGetSelection();
+                discuss.destroy();
+                done();
+        });
+    });
+});
+
 });
 });