// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // @dart = 2.8 import 'package:flutter/rendering.dart'; import 'package:flutter/widgets.dart'; import 'package:flutter_test/flutter_test.dart'; void main() { testWidgets('Render and element tree stay in sync when keyed children move around', (WidgetTester tester) async { // Regression test for https://github.com/flutter/flutter/issues/48855. await tester.pumpWidget( Directionality( textDirection: TextDirection.ltr, child: Column( children: const <Widget>[ Text('0', key: ValueKey<int>(0)), Text('1', key: ValueKey<int>(1)), Text('2', key: ValueKey<int>(2)), Text('3', key: ValueKey<int>(3)), Text('4', key: ValueKey<int>(4)), Text('5', key: ValueKey<int>(5)), Text('6', key: ValueKey<int>(6)), Text('7', key: ValueKey<int>(7)), Text('8', key: ValueKey<int>(8)), ], ), ), ); expect( _getChildOrder(tester.renderObject<RenderFlex>(find.byType(Column))), <String>['0', '1', '2', '3', '4', '5', '6', '7', '8'], ); await tester.pumpWidget( Directionality( textDirection: TextDirection.ltr, child: Column( children: const <Widget>[ Text('0', key: ValueKey<int>(0)), Text('6', key: ValueKey<int>(6)), Text('7', key: ValueKey<int>(7)), Text('8', key: ValueKey<int>(8)), Text('1', key: ValueKey<int>(1)), Text('2', key: ValueKey<int>(2)), Text('3', key: ValueKey<int>(3)), Text('4', key: ValueKey<int>(4)), Text('5', key: ValueKey<int>(5)), ], ), ), ); expect( _getChildOrder(tester.renderObject<RenderFlex>(find.byType(Column))), <String>['0', '6', '7', '8', '1', '2', '3', '4', '5'], ); }); } // Do not use tester.renderObjectList(find.byType(RenderParagraph). That returns // the RenderObjects in the order of their associated RenderObjectWidgets. The // point of this test is to assert the children order in the render tree, though. List<String> _getChildOrder(RenderFlex flex) { final List<String> childOrder = <String>[]; flex.visitChildren((RenderObject child) { childOrder.add(((child as RenderParagraph).text as TextSpan).text); }); return childOrder; }