Chat: it should be possible to update one item or item's field (T1290746)

Author: Zedwag

packages/devextreme/js/__internal/ui/chat/chat.ts

@@ -564,7 +564,7 @@ class Chat extends Widget<Properties> {
       case 'editing':
         break;
       case 'items':
-        this._messageList.option(name, value);
+        this._messageList.option(name, this.option('items'));
         this._updateMessageBoxAria();
         break;
       case 'dataSource':

packages/devextreme/testing/tests/DevExpress.ui.widgets/chatParts/chat.tests.js

@@ -273,6 +273,30 @@ QUnit.module('Chat', () => {
             assert.deepEqual(messageList.option('items'), newItems, 'items value is updated');
         });
 
+        QUnit.test('items should be passed to messageList after update only one item (T1290746)', function(assert) {
+            this.reinit({
+                items: [{ text: 'one' }, { text: 'two' }],
+            });
+
+            this.instance.option('items[0]', { text: 'new one' });
+
+            const messageList = this.getMessageList();
+
+            assert.deepEqual(messageList.option('items'), [{ text: 'new one' }, { text: 'two' }], 'items value is updated');
+        });
+
+        QUnit.test('items should be passed to messageList after update only one item field (T1290746)', function(assert) {
+            this.reinit({
+                items: [{ text: 'one' }, { text: 'two' }],
+            });
+
+            this.instance.option('items[0].text', 'new one');
+
+            const messageList = this.getMessageList();
+
+            assert.deepEqual(messageList.option('items'), [{ text: 'new one' }, { text: 'two' }], 'items value is updated');
+        });
+
         ['showDayHeaders', 'showAvatar', 'showUserName', 'showMessageTimestamp'].forEach(option => {
             QUnit.test(`Chat should pass ${option} to messageList on init`, function(assert) {
                 this.reinit({