Autocomplete: dataSource should load new items only when searchTimeout is up (T880996)

js/ui/autocomplete.js

@@ -3,6 +3,7 @@ const noop = require('../core/utils/common').noop;
 const registerComponent = require('../core/component_registrator');
 const extend = require('../core/utils/extend').extend;
 const DropDownList = require('./drop_down_editor/ui.drop_down_list');
+const Deferred = require('../core/utils/deferred').Deferred;
 
 const AUTOCOMPLETE_CLASS = 'dx-autocomplete';
 const AUTOCOMPLETE_POPUP_WRAPPER_CLASS = 'dx-autocomplete-popup-wrapper';
@@ -151,6 +152,12 @@ const Autocomplete = DropDownList.inherit({
         this.close();
     },
 
+    _loadItem: function(value, cache) {
+        const selectedItem = this._getItemFromPlain(value, cache);
+
+        return new Deferred().resolve(selectedItem).promise();
+    },
+
     _dataSourceOptions: function() {
         return {
             paginate: true,

testing/tests/DevExpress.ui.widgets.editors/autocomplete.tests.js

@@ -450,6 +450,40 @@ QUnit.module('dxAutocomplete', {
         }
     });
 
+    QUnit.test('dataSource should load new items only when searchTimeout is up (T880996)', function(assert) {
+        const keyboard = this.keyboard;
+        const data = [{
+            ID: 1,
+            Name: 'Item 11'
+        }, {
+            ID: 2,
+            Name: 'Item 12'
+        }, {
+            ID: 3,
+            Name: 'Item 22'
+        }];
+        const loadMock = sinon.stub().returns(data);
+
+        this.element.dxAutocomplete({
+            dataSource: {
+                load: loadMock
+            },
+            searchTimeout: 500,
+            valueExpr: 'Name'
+        });
+
+        assert.strictEqual(loadMock.callCount, 1, 'dataSource load is called on init');
+
+        keyboard
+            .type('Item')
+            .change();
+
+        assert.strictEqual(loadMock.callCount, 1, 'dataSource load is not called immediately after typing');
+
+        this.clock.tick(500);
+        assert.strictEqual(loadMock.callCount, 2, 'dataSource is filtered when timeout is up');
+    });
+
     QUnit.test('arrow_down/arrow_up/enter provide item navigation and selection', function(assert) {
         if(devices.real().deviceType !== 'desktop') {
             assert.ok(true, 'test does not actual for mobile devices');