DropDownList: Displayed text should be correct when items have nested items field and group is disabled (T1292151)

Author: Zedwag

packages/devextreme/js/__internal/ui/drop_down_editor/m_drop_down_list.ts

@@ -381,11 +381,12 @@ class DropDownList<
 
   _getPlainItems(items?) {
     let plainItems: any = [];
+    const grouped = this._getGroupedOption();
 
     items = items || this.option('items') || this._dataSource.items() || [];
 
     for (let i = 0; i < items.length; i++) {
-      if (items[i]?.items) {
+      if (grouped && items[i]?.items) {
         plainItems = plainItems.concat(items[i].items);
       } else {
         plainItems.push(items[i]);

packages/devextreme/testing/tests/DevExpress.ui.widgets.editors/dropDownList.tests.js

@@ -990,6 +990,21 @@ QUnit.module('items & dataSource', moduleConfig, () => {
             assert.strictEqual(this.dropDownList.option('selectedItem'), null, 'byKey result is ignored');
         });
     });
+
+    QUnit.test('_getPlainItems should return correct items when they have nested items field and grouping is disabled (T1292151)', function(assert) {
+        const nestedItems = [{ id: 1, text: 'unexpected text' }];
+        const items = [{ id: 1, text: 'item 1', items: nestedItems }];
+
+        const dropDownList = $('#dropDownList').dxDropDownList({
+            items,
+            displayExpr: 'text',
+            valueExpr: 'id',
+        }).dxDropDownList('instance');
+
+        const plainItems = dropDownList._getPlainItems();
+
+        assert.deepEqual(plainItems, items, 'items are correct');
+    });
 });
 
 QUnit.module('selectedItem', moduleConfig, () => {

packages/devextreme/testing/tests/DevExpress.ui.widgets.editors/lookup.tests.js

@@ -65,7 +65,6 @@ QUnit.testStart(function() {
     $('#widthRootStyle').css('width', '300px');
 });
 
-const OVERLAY_CLASS = 'dx-overlay';
 const OVERLAY_SHADER_CLASS = 'dx-overlay-shader';
 const OVERLAY_WRAPPER_CLASS = 'dx-overlay-wrapper';
 const OVERLAY_CONTENT_CLASS = 'dx-overlay-content';
@@ -2108,6 +2107,22 @@ QUnit.module('options', {
 
         assert.strictEqual($field.attr('custom'), undefined, 'custom attribute is set correctly');
     });
+
+    QUnit.test('Displayed text should be correct when items have nested items field and grouping is disabled (T1292151)', function(assert) {
+        const $lookup = $('#lookup').dxLookup({
+            items: [
+                { id: 1, text: 'item 1', items: [{ id: 1, text: 'unexpected text' }] },
+            ],
+            value: 1,
+            displayExpr: 'text',
+            valueExpr: 'id',
+        });
+
+        const $input = $lookup.find(`.${LOOKUP_FIELD_CLASS}`);
+        const displayedText = $input.text();
+
+        assert.strictEqual(displayedText, 'item 1', 'input value is correct');
+    });
 });
 
 QUnit.module('popup options', {

packages/devextreme/testing/tests/DevExpress.ui.widgets.editors/selectBox.tests.js

@@ -1572,6 +1572,22 @@ QUnit.module('widget options', moduleSetup, () => {
             assert.ok(false, 'error is trown');
         }
     });
+
+    QUnit.test('Displayed text should be correct when items have nested items field and grouping is disabled (T1292151)', function(assert) {
+        const $selectBox = $('#selectBox').dxSelectBox({
+            items: [
+                { id: 1, text: 'item 1', items: [{ id: 1, text: 'unexpected text' }] },
+            ],
+            value: 1,
+            displayExpr: 'text',
+            valueExpr: 'id',
+        });
+
+        const $input = $selectBox.find(`.${TEXTEDITOR_INPUT_CLASS}`);
+        const displayedText = $input.val();
+
+        assert.strictEqual(displayedText, 'item 1', 'input value is correct');
+    });
 });
 
 QUnit.module('clearButton', moduleSetup, () => {