List (Sortable) - Fix item dragging to the top position when allowReordering is false (T856292)

js/ui/sortable.js

@@ -254,9 +254,10 @@ const Sortable = Draggable.inherit({
     },
 
     _isValidPoint: function(visibleIndex, draggableVisibleIndex, dropInsideItem) {
+        const allowDropInsideItem = this.option('allowDropInsideItem');
         const allowReordering = dropInsideItem || this._allowReordering();
 
-        if(!allowReordering && visibleIndex !== 0) {
+        if(!allowReordering && (visibleIndex !== 0 || !allowDropInsideItem)) {
             return false;
         }
 

testing/tests/DevExpress.ui.widgets/listParts/editingUITests.js

@@ -2926,3 +2926,26 @@ QUnit.test('items should reset positions after dragend', function(assert) {
     });
 });
 
+// T856292
+QUnit.test('Drag and drop item to the top of the list should not work when allowReordering is false', function(assert) {
+    const $list = $('#list').dxList({
+        items: ['0', '1', '2'],
+        itemDragging: {
+            allowReordering: false,
+            group: 'shared'
+        }
+    });
+
+    let $items = $list.find(toSelector(LIST_ITEM_CLASS));
+    const $item3 = $items.eq(2);
+    const pointer = reorderingPointerMock($item3, this.clock);
+
+    pointer.dragStart(0.5).drag(-1).drag(-1.5).dragEnd();
+
+    $items = $list.find(toSelector(LIST_ITEM_CLASS));
+    $.each($items, (index, item) => {
+        const $item = $(item);
+
+        assert.equal($item.text(), index, 'item text');
+    });
+});

testing/tests/DevExpress.ui.widgets/sortable.tests.js

@@ -361,6 +361,24 @@ QUnit.test('option changing', function(assert) {
     assert.strictEqual(this.$element.children().first().text(), 'item1', 'first item is not changed');
 });
 
+QUnit.test('Move to top if allowReordering is false', function(assert) {
+    // arrange
+    const onDragChangeSpy = sinon.spy();
+
+    this.createSortable({
+        allowReordering: false,
+        dropFeedbackMode: 'indicate',
+        onDragChange: onDragChangeSpy
+    });
+
+    // act
+    pointerMock(this.$element.children().eq(1)).start().down(15, 45).move(0, -45);
+
+    // assert
+    assert.strictEqual(onDragChangeSpy.callCount, 0, 'onDragChange event is not called');
+    assert.strictEqual($('.dx-sortable-placeholder').length, 0, 'placeholder does not exist');
+});
+
 
 QUnit.module('placeholder and source', moduleConfig);