packages/flutter/test/widgets/list_view_test.dart - mirrors/flutter - Git at Google

 // 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.

 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';

 import '../rendering/mock_canvas.dart';
 import '../rendering/rendering_tester.dart';

 class TestSliverChildListDelegate extends SliverChildListDelegate {
   TestSliverChildListDelegate(List<Widget> children) : super(children);

   final List<String> log = <String>[];

   @override
   void didFinishLayout(int firstIndex, int lastIndex) {
     log.add('didFinishLayout firstIndex=$firstIndex lastIndex=$lastIndex');
   }
 }

 class Alive extends StatefulWidget {
   const Alive(this.alive, this.index, { Key? key }) : super(key: key);
   final bool alive;
   final int index;

   @override
   AliveState createState() => AliveState();

   @override
   String toString({ DiagnosticLevel minLevel = DiagnosticLevel.info }) => '$index $alive';
 }

 class AliveState extends State<Alive> with AutomaticKeepAliveClientMixin {
   @override
   bool get wantKeepAlive => widget.alive;

   @override
   Widget build(BuildContext context) {
     super.build(context);
     return Text('${widget.index}:$wantKeepAlive');
   }
 }

 typedef WhetherToKeepAlive = bool Function(int);
 class _StatefulListView extends StatefulWidget {
   const _StatefulListView(this.aliveCallback);

   final WhetherToKeepAlive aliveCallback;
   @override
   _StatefulListViewState createState() => _StatefulListViewState();
 }

 class _StatefulListViewState extends State<_StatefulListView> {
   @override
   Widget build(BuildContext context) {
     return GestureDetector(
       // force a rebuild - the test(s) using this are verifying that the list is
       // still correct after rebuild
       onTap: () => setState,
       child: Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           children: List<Widget>.generate(200, (int i) {
             return Builder(
               builder: (BuildContext context) {
                 return Alive(widget.aliveCallback(i), i);
               },
             );
           }),
         ),
       ),
     );
   }
 }

 void main() {
   testWidgets('ListView default control', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: ListView(itemExtent: 100.0),
         ),
       ),
     );
   });

   testWidgets('ListView itemExtent control test', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           itemExtent: 200.0,
           children: List<Widget>.generate(20, (int i) {
             return Container(
               color: Colors.green,
               child: Text('$i'),
             );
           }),
         ),
       ),
     );

     final RenderBox box = tester.renderObject<RenderBox>(find.byType(Container).first);
     expect(box.size.height, equals(200.0));

     expect(find.text('0'), findsOneWidget);
     expect(find.text('1'), findsOneWidget);
     expect(find.text('2'), findsOneWidget);
     expect(find.text('3'), findsNothing);
     expect(find.text('4'), findsNothing);

     await tester.drag(find.byType(ListView), const Offset(0.0, -250.0));
     await tester.pump();

     expect(find.text('0'), findsNothing);
     expect(find.text('1'), findsOneWidget);
     expect(find.text('2'), findsOneWidget);
     expect(find.text('3'), findsOneWidget);
     expect(find.text('4'), findsOneWidget);
     expect(find.text('5'), findsNothing);
     expect(find.text('6'), findsNothing);

     await tester.drag(find.byType(ListView), const Offset(0.0, 200.0));
     await tester.pump();

     expect(find.text('0'), findsOneWidget);
     expect(find.text('1'), findsOneWidget);
     expect(find.text('2'), findsOneWidget);
     expect(find.text('3'), findsOneWidget);
     expect(find.text('4'), findsNothing);
     expect(find.text('5'), findsNothing);
   });

   testWidgets('ListView large scroll jump', (WidgetTester tester) async {
     final List<int> log = <int>[];

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           itemExtent: 200.0,
           children: List<Widget>.generate(20, (int i) {
             return Builder(
               builder: (BuildContext context) {
                 log.add(i);
                 return Text('$i');
               },
             );
           }),
         ),
       ),
     );

     expect(log, equals(<int>[0, 1, 2, 3, 4]));
     log.clear();

     final ScrollableState state = tester.state(find.byType(Scrollable));
     final ScrollPosition position = state.position;
     position.jumpTo(2025.0);

     expect(log, isEmpty);
     await tester.pump();

     expect(log, equals(<int>[8, 9, 10, 11, 12, 13, 14]));
     log.clear();

     position.jumpTo(975.0);

     expect(log, isEmpty);
     await tester.pump();

     expect(log, equals(<int>[7, 6, 5, 4, 3]));
     log.clear();
   });

   testWidgets('ListView large scroll jump and keepAlive first child not keepAlive', (WidgetTester tester) async {
     Future<void> checkAndScroll([ String zero = '0:false' ]) async {
       expect(find.text(zero), findsOneWidget);
       expect(find.text('1:false'), findsOneWidget);
       expect(find.text('2:false'), findsOneWidget);
       expect(find.text('3:true'), findsOneWidget);
       expect(find.text('116:false'), findsNothing);
       final ScrollableState state = tester.state(find.byType(Scrollable));
       final ScrollPosition position = state.position;
       position.jumpTo(1025.0);

       await tester.pump();

       expect(find.text(zero), findsNothing);
       expect(find.text('1:false'), findsNothing);
       expect(find.text('2:false'), findsNothing);
       expect(find.text('3:true', skipOffstage: false), findsOneWidget);
       expect(find.text('116:false'), findsOneWidget);

       await tester.tapAt(const Offset(100.0, 100.0));
       position.jumpTo(0.0);
       await tester.pump();
       await tester.pump();

       expect(find.text(zero), findsOneWidget);
       expect(find.text('1:false'), findsOneWidget);
       expect(find.text('2:false'), findsOneWidget);
       expect(find.text('3:true'), findsOneWidget);
     }

     await tester.pumpWidget(_StatefulListView((int i) => i > 2 && i % 3 == 0));
     await checkAndScroll();

     await tester.pumpWidget(_StatefulListView((int i) => i % 3 == 0));
     await checkAndScroll('0:true');
   });

   testWidgets('ListView can build out of underflow', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           itemExtent: 100.0,
         ),
       ),
     );

     expect(find.text('0'), findsNothing);
     expect(find.text('1'), findsNothing);
     expect(find.text('2'), findsNothing);
     expect(find.text('3'), findsNothing);
     expect(find.text('4'), findsNothing);
     expect(find.text('5'), findsNothing);

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           itemExtent: 100.0,
           children: List<Widget>.generate(2, (int i) {
             return Text('$i');
           }),
         ),
       ),
     );

     expect(find.text('0'), findsOneWidget);
     expect(find.text('1'), findsOneWidget);
     expect(find.text('2'), findsNothing);
     expect(find.text('3'), findsNothing);
     expect(find.text('4'), findsNothing);
     expect(find.text('5'), findsNothing);

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           itemExtent: 100.0,
           children: List<Widget>.generate(5, (int i) {
             return Text('$i');
           }),
         ),
       ),
     );

     expect(find.text('0'), findsOneWidget);
     expect(find.text('1'), findsOneWidget);
     expect(find.text('2'), findsOneWidget);
     expect(find.text('3'), findsOneWidget);
     expect(find.text('4'), findsOneWidget);
     expect(find.text('5'), findsNothing);
   });

   testWidgets('ListView can build out of overflow padding', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             width: 0.0,
             height: 0.0,
             child: ListView(
               padding: const EdgeInsets.all(8.0),
               children: const <Widget>[
                 Text('padded', textDirection: TextDirection.ltr),
               ],
             ),
           ),
         ),
       ),
     );
     expect(find.text('padded', skipOffstage: false), findsOneWidget);
   });

   testWidgets('ListView with itemExtent in unbounded context', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: SingleChildScrollView(
           child: ListView(
             itemExtent: 100.0,
             shrinkWrap: true,
             children: List<Widget>.generate(20, (int i) {
               return Text('$i');
             }),
           ),
         ),
       ),
     );

     expect(find.text('0'), findsOneWidget);
     expect(find.text('19'), findsOneWidget);
   });

   testWidgets('ListView with shrink wrap in bounded context correctly uses cache extent', (WidgetTester tester) async {
     final SemanticsHandle handle = tester.ensureSemantics();
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: SizedBox(
           height: 400,
           child: ListView(
             itemExtent: 100.0,
             shrinkWrap: true,
             children: List<Widget>.generate(20, (int i) {
               return Text('Text $i');
             }),
           ),
         ),
       ),
     );
     expect(tester.getSemantics(find.text('Text 5')), matchesSemantics());
     expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
     expect(tester.getSemantics(find.text('Text 7', skipOffstage: false)), matchesSemantics(isHidden: true));
     expect(tester.getSemantics(find.text('Text 8', skipOffstage: false)), matchesSemantics(isHidden: true));
     handle.dispose();
   });

   testWidgets('ListView hidden items should stay hidden if their semantics are updated', (WidgetTester tester) async {
     final SemanticsHandle handle = tester.ensureSemantics();
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: SizedBox(
           height: 400,
           child: ListView(
             itemExtent: 100.0,
             shrinkWrap: true,
             children: List<Widget>.generate(20, (int i) {
               return Text('Text $i');
             }),
           ),
         ),
       ),
     );
     // Scrollable maybe be marked dirty after layout.
     await tester.pumpAndSettle();
     expect(tester.getSemantics(find.text('Text 5')), matchesSemantics());
     expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
     expect(tester.getSemantics(find.text('Text 7', skipOffstage: false)), matchesSemantics(isHidden: true));
     expect(tester.getSemantics(find.text('Text 8', skipOffstage: false)), matchesSemantics(isHidden: true));

     // Marks Text 6 semantics as dirty.
     final RenderObject text6 = tester.renderObject(find.text('Text 6', skipOffstage: false));
     text6.markNeedsSemanticsUpdate();

     // Verify the semantics is still hidden.
     await tester.pump();
     expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));

     handle.dispose();
   });

   testWidgets('didFinishLayout has correct indices', (WidgetTester tester) async {
     final TestSliverChildListDelegate delegate = TestSliverChildListDelegate(
       List<Widget>.generate(
         20,
         (int i) {
           return Text('$i', textDirection: TextDirection.ltr);
         },
       ),
     );

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.custom(
           itemExtent: 110.0,
           childrenDelegate: delegate,
         ),
       ),
     );

     expect(delegate.log, equals(<String>['didFinishLayout firstIndex=0 lastIndex=7']));
     delegate.log.clear();

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.custom(
           itemExtent: 210.0,
           childrenDelegate: delegate,
         ),
       ),
     );

     expect(delegate.log, equals(<String>['didFinishLayout firstIndex=0 lastIndex=4']));
     delegate.log.clear();

     await tester.drag(find.byType(ListView), const Offset(0.0, -600.0));

     expect(delegate.log, isEmpty);

     await tester.pump();

     expect(delegate.log, equals(<String>['didFinishLayout firstIndex=1 lastIndex=6']));
     delegate.log.clear();
   });

   testWidgets('ListView automatically pad MediaQuery on axis', (WidgetTester tester) async {
     EdgeInsets? innerMediaQueryPadding;

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: MediaQuery(
           data: const MediaQueryData(
             padding: EdgeInsets.all(30.0),
           ),
           child: ListView(
             children: <Widget>[
               const Text('top', textDirection: TextDirection.ltr),
               Builder(builder: (BuildContext context) {
                 innerMediaQueryPadding = MediaQuery.of(context).padding;
                 return Container();
               }),
             ],
           ),
         ),
       ),
     );
     // Automatically apply the top/bottom padding into sliver.
     expect(tester.getTopLeft(find.text('top')).dy, 30.0);
     // Leave left/right padding as is for children.
     expect(innerMediaQueryPadding, const EdgeInsets.symmetric(horizontal: 30.0));
   });

   testWidgets('ListView clips if overflow is smaller than cacheExtent', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/17426.

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             height: 200.0,
             child: ListView(
               cacheExtent: 500.0,
               children: <Widget>[
                 Container(
                   height: 90.0,
                 ),
                 Container(
                   height: 110.0,
                 ),
                 Container(
                   height: 80.0,
                 ),
               ],
             ),
           ),
         ),
       ),
     );

     expect(find.byType(Viewport), paints..clipRect());
   });

   testWidgets('ListView does not clips if no overflow', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             height: 200.0,
             child: ListView(
               cacheExtent: 500.0,
               children: const <Widget>[
                 SizedBox(
                   height: 100.0,
                 ),
               ],
             ),
           ),
         ),
       ),
     );

     expect(find.byType(Viewport), isNot(paints..clipRect()));
   });

   testWidgets('ListView (fixed extent) clips if overflow is smaller than cacheExtent', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/17426.

     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             height: 200.0,
             child: ListView(
               itemExtent: 100.0,
               cacheExtent: 500.0,
               children: const <Widget>[
                 SizedBox(
                   height: 100.0,
                 ),
                 SizedBox(
                   height: 100.0,
                 ),
                 SizedBox(
                   height: 100.0,
                 ),
               ],
             ),
           ),
         ),
       ),
     );

     expect(find.byType(Viewport), paints..clipRect());
   });

   testWidgets('ListView (fixed extent) does not clips if no overflow', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             height: 200.0,
             child: ListView(
               itemExtent: 100.0,
               cacheExtent: 500.0,
               children: const <Widget>[
                 SizedBox(
                   height: 100.0,
                 ),
               ],
             ),
           ),
         ),
       ),
     );

     expect(find.byType(Viewport), isNot(paints..clipRect()));
   });

   testWidgets('ListView.horizontal has implicit scrolling by default', (WidgetTester tester) async {
     final SemanticsHandle handle = tester.ensureSemantics();
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             height: 200.0,
             child: ListView(
               scrollDirection: Axis.horizontal,
               itemExtent: 100.0,
               children: const <Widget>[
                 SizedBox(
                   height: 100.0,
                 ),
               ],
             ),
           ),
         ),
       ),
     );
     expect(tester.getSemantics(find.byType(Scrollable)), matchesSemantics(
       children: <Matcher>[
         matchesSemantics(
           children: <Matcher>[
             matchesSemantics(hasImplicitScrolling: true),
           ],
         ),
       ],
     ));
     handle.dispose();
   });

   testWidgets('Updates viewport dimensions when scroll direction changes', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/43380.
     final ScrollController controller = ScrollController();

     Widget buildListView({ required Axis scrollDirection }) {
       assert(scrollDirection != null);
       return Directionality(
         textDirection: TextDirection.ltr,
         child: Center(
           child: SizedBox(
             height: 200.0,
             width: 100.0,
             child: ListView(
               controller: controller,
               scrollDirection: scrollDirection,
               itemExtent: 50.0,
               children: const <Widget>[
                 SizedBox(
                   height: 50.0,
                   width: 50.0,
                 ),
               ],
             ),
           ),
         ),
       );
     }

     await tester.pumpWidget(buildListView(scrollDirection: Axis.horizontal));
     expect(controller.position.viewportDimension, 100.0);

     await tester.pumpWidget(buildListView(scrollDirection: Axis.vertical));
     expect(controller.position.viewportDimension, 200.0);

     await tester.pumpWidget(buildListView(scrollDirection: Axis.horizontal));
     expect(controller.position.viewportDimension, 100.0);
   });

   testWidgets('ListView respects clipBehavior', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           children: <Widget>[Container(height: 2000.0)],
         ),
       ),
     );

     // 1st, check that the render object has received the default clip behavior.
     final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
     expect(renderObject.clipBehavior, equals(Clip.hardEdge));

     // 2nd, check that the painting context has received the default clip behavior.
     final TestClipPaintingContext context = TestClipPaintingContext();
     renderObject.paint(context, Offset.zero);
     expect(context.clipBehavior, equals(Clip.hardEdge));

     // 3rd, pump a new widget to check that the render object can update its clip behavior.
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
           clipBehavior: Clip.antiAlias,
           children: <Widget>[Container(height: 2000.0)],
         ),
       ),
     );
     expect(renderObject.clipBehavior, equals(Clip.antiAlias));

     // 4th, check that a non-default clip behavior can be sent to the painting context.
     renderObject.paint(context, Offset.zero);
     expect(context.clipBehavior, equals(Clip.antiAlias));
   });

   testWidgets('ListView.builder respects clipBehavior', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.builder(
           itemCount: 10,
           itemBuilder: (BuildContext _, int __) => Container(height: 2000.0),
           clipBehavior: Clip.antiAlias,
         ),
       ),
     );
     final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
     expect(renderObject.clipBehavior, equals(Clip.antiAlias));
   });

   testWidgets('ListView.custom respects clipBehavior', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.custom(
           childrenDelegate: SliverChildBuilderDelegate(
             (BuildContext context, int index) => Container(height: 2000.0),
             childCount: 1,
           ),
           clipBehavior: Clip.antiAlias,
         ),
       ),
     );
     final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
     expect(renderObject.clipBehavior, equals(Clip.antiAlias));
   });

   testWidgets('ListView.separated respects clipBehavior', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.separated(
           itemCount: 10,
           itemBuilder: (BuildContext _, int __) => Container(height: 2000.0),
           separatorBuilder: (BuildContext _, int __) => const Divider(),
           clipBehavior: Clip.antiAlias,
         ),
       ),
     );
     final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
     expect(renderObject.clipBehavior, equals(Clip.antiAlias));
   });
 }
	// 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.

	import 'package:flutter/material.dart';
	import 'package:flutter/rendering.dart';
	import 'package:flutter_test/flutter_test.dart';

	import '../rendering/mock_canvas.dart';
	import '../rendering/rendering_tester.dart';

	class TestSliverChildListDelegate extends SliverChildListDelegate {
	TestSliverChildListDelegate(List<Widget> children) : super(children);

	final List<String> log = <String>[];

	@override
	void didFinishLayout(int firstIndex, int lastIndex) {
	log.add('didFinishLayout firstIndex=$firstIndex lastIndex=$lastIndex');
	}
	}

	class Alive extends StatefulWidget {
	const Alive(this.alive, this.index, { Key? key }) : super(key: key);
	final bool alive;
	final int index;

	@override
	AliveState createState() => AliveState();

	@override
	String toString({ DiagnosticLevel minLevel = DiagnosticLevel.info }) => '$index $alive';
	}

	class AliveState extends State<Alive> with AutomaticKeepAliveClientMixin {
	@override
	bool get wantKeepAlive => widget.alive;

	@override
	Widget build(BuildContext context) {
	super.build(context);
	return Text('${widget.index}:$wantKeepAlive');
	}
	}

	typedef WhetherToKeepAlive = bool Function(int);
	class _StatefulListView extends StatefulWidget {
	const _StatefulListView(this.aliveCallback);

	final WhetherToKeepAlive aliveCallback;
	@override
	_StatefulListViewState createState() => _StatefulListViewState();
	}

	class _StatefulListViewState extends State<_StatefulListView> {
	@override
	Widget build(BuildContext context) {
	return GestureDetector(
	// force a rebuild - the test(s) using this are verifying that the list is
	// still correct after rebuild
	onTap: () => setState,
	child: Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	children: List<Widget>.generate(200, (int i) {
	return Builder(
	builder: (BuildContext context) {
	return Alive(widget.aliveCallback(i), i);
	},
	);
	}),
	),
	),
	);
	}
	}

	void main() {
	testWidgets('ListView default control', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: ListView(itemExtent: 100.0),
	),
	),
	);
	});

	testWidgets('ListView itemExtent control test', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	itemExtent: 200.0,
	children: List<Widget>.generate(20, (int i) {
	return Container(
	color: Colors.green,
	child: Text('$i'),
	);
	}),
	),
	),
	);

	final RenderBox box = tester.renderObject<RenderBox>(find.byType(Container).first);
	expect(box.size.height, equals(200.0));

	expect(find.text('0'), findsOneWidget);
	expect(find.text('1'), findsOneWidget);
	expect(find.text('2'), findsOneWidget);
	expect(find.text('3'), findsNothing);
	expect(find.text('4'), findsNothing);

	await tester.drag(find.byType(ListView), const Offset(0.0, -250.0));
	await tester.pump();

	expect(find.text('0'), findsNothing);
	expect(find.text('1'), findsOneWidget);
	expect(find.text('2'), findsOneWidget);
	expect(find.text('3'), findsOneWidget);
	expect(find.text('4'), findsOneWidget);
	expect(find.text('5'), findsNothing);
	expect(find.text('6'), findsNothing);

	await tester.drag(find.byType(ListView), const Offset(0.0, 200.0));
	await tester.pump();

	expect(find.text('0'), findsOneWidget);
	expect(find.text('1'), findsOneWidget);
	expect(find.text('2'), findsOneWidget);
	expect(find.text('3'), findsOneWidget);
	expect(find.text('4'), findsNothing);
	expect(find.text('5'), findsNothing);
	});

	testWidgets('ListView large scroll jump', (WidgetTester tester) async {
	final List<int> log = <int>[];

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	itemExtent: 200.0,
	children: List<Widget>.generate(20, (int i) {
	return Builder(
	builder: (BuildContext context) {
	log.add(i);
	return Text('$i');
	},
	);
	}),
	),
	),
	);

	expect(log, equals(<int>[0, 1, 2, 3, 4]));
	log.clear();

	final ScrollableState state = tester.state(find.byType(Scrollable));
	final ScrollPosition position = state.position;
	position.jumpTo(2025.0);

	expect(log, isEmpty);
	await tester.pump();

	expect(log, equals(<int>[8, 9, 10, 11, 12, 13, 14]));
	log.clear();

	position.jumpTo(975.0);

	expect(log, isEmpty);
	await tester.pump();

	expect(log, equals(<int>[7, 6, 5, 4, 3]));
	log.clear();
	});

	testWidgets('ListView large scroll jump and keepAlive first child not keepAlive', (WidgetTester tester) async {
	Future<void> checkAndScroll([ String zero = '0:false' ]) async {
	expect(find.text(zero), findsOneWidget);
	expect(find.text('1:false'), findsOneWidget);
	expect(find.text('2:false'), findsOneWidget);
	expect(find.text('3:true'), findsOneWidget);
	expect(find.text('116:false'), findsNothing);
	final ScrollableState state = tester.state(find.byType(Scrollable));
	final ScrollPosition position = state.position;
	position.jumpTo(1025.0);

	await tester.pump();

	expect(find.text(zero), findsNothing);
	expect(find.text('1:false'), findsNothing);
	expect(find.text('2:false'), findsNothing);
	expect(find.text('3:true', skipOffstage: false), findsOneWidget);
	expect(find.text('116:false'), findsOneWidget);

	await tester.tapAt(const Offset(100.0, 100.0));
	position.jumpTo(0.0);
	await tester.pump();
	await tester.pump();

	expect(find.text(zero), findsOneWidget);
	expect(find.text('1:false'), findsOneWidget);
	expect(find.text('2:false'), findsOneWidget);
	expect(find.text('3:true'), findsOneWidget);
	}

	await tester.pumpWidget(_StatefulListView((int i) => i > 2 && i % 3 == 0));
	await checkAndScroll();

	await tester.pumpWidget(_StatefulListView((int i) => i % 3 == 0));
	await checkAndScroll('0:true');
	});

	testWidgets('ListView can build out of underflow', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	itemExtent: 100.0,
	),
	),
	);

	expect(find.text('0'), findsNothing);
	expect(find.text('1'), findsNothing);
	expect(find.text('2'), findsNothing);
	expect(find.text('3'), findsNothing);
	expect(find.text('4'), findsNothing);
	expect(find.text('5'), findsNothing);

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	itemExtent: 100.0,
	children: List<Widget>.generate(2, (int i) {
	return Text('$i');
	}),
	),
	),
	);

	expect(find.text('0'), findsOneWidget);
	expect(find.text('1'), findsOneWidget);
	expect(find.text('2'), findsNothing);
	expect(find.text('3'), findsNothing);
	expect(find.text('4'), findsNothing);
	expect(find.text('5'), findsNothing);

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	itemExtent: 100.0,
	children: List<Widget>.generate(5, (int i) {
	return Text('$i');
	}),
	),
	),
	);

	expect(find.text('0'), findsOneWidget);
	expect(find.text('1'), findsOneWidget);
	expect(find.text('2'), findsOneWidget);
	expect(find.text('3'), findsOneWidget);
	expect(find.text('4'), findsOneWidget);
	expect(find.text('5'), findsNothing);
	});

	testWidgets('ListView can build out of overflow padding', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	width: 0.0,
	height: 0.0,
	child: ListView(
	padding: const EdgeInsets.all(8.0),
	children: const <Widget>[
	Text('padded', textDirection: TextDirection.ltr),
	],
	),
	),
	),
	),
	);
	expect(find.text('padded', skipOffstage: false), findsOneWidget);
	});

	testWidgets('ListView with itemExtent in unbounded context', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: SingleChildScrollView(
	child: ListView(
	itemExtent: 100.0,
	shrinkWrap: true,
	children: List<Widget>.generate(20, (int i) {
	return Text('$i');
	}),
	),
	),
	),
	);

	expect(find.text('0'), findsOneWidget);
	expect(find.text('19'), findsOneWidget);
	});

	testWidgets('ListView with shrink wrap in bounded context correctly uses cache extent', (WidgetTester tester) async {
	final SemanticsHandle handle = tester.ensureSemantics();
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: SizedBox(
	height: 400,
	child: ListView(
	itemExtent: 100.0,
	shrinkWrap: true,
	children: List<Widget>.generate(20, (int i) {
	return Text('Text $i');
	}),
	),
	),
	),
	);
	expect(tester.getSemantics(find.text('Text 5')), matchesSemantics());
	expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
	expect(tester.getSemantics(find.text('Text 7', skipOffstage: false)), matchesSemantics(isHidden: true));
	expect(tester.getSemantics(find.text('Text 8', skipOffstage: false)), matchesSemantics(isHidden: true));
	handle.dispose();
	});

	testWidgets('ListView hidden items should stay hidden if their semantics are updated', (WidgetTester tester) async {
	final SemanticsHandle handle = tester.ensureSemantics();
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: SizedBox(
	height: 400,
	child: ListView(
	itemExtent: 100.0,
	shrinkWrap: true,
	children: List<Widget>.generate(20, (int i) {
	return Text('Text $i');
	}),
	),
	),
	),
	);
	// Scrollable maybe be marked dirty after layout.
	await tester.pumpAndSettle();
	expect(tester.getSemantics(find.text('Text 5')), matchesSemantics());
	expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
	expect(tester.getSemantics(find.text('Text 7', skipOffstage: false)), matchesSemantics(isHidden: true));
	expect(tester.getSemantics(find.text('Text 8', skipOffstage: false)), matchesSemantics(isHidden: true));

	// Marks Text 6 semantics as dirty.
	final RenderObject text6 = tester.renderObject(find.text('Text 6', skipOffstage: false));
	text6.markNeedsSemanticsUpdate();

	// Verify the semantics is still hidden.
	await tester.pump();
	expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));

	handle.dispose();
	});

	testWidgets('didFinishLayout has correct indices', (WidgetTester tester) async {
	final TestSliverChildListDelegate delegate = TestSliverChildListDelegate(
	List<Widget>.generate(
	20,
	(int i) {
	return Text('$i', textDirection: TextDirection.ltr);
	},
	),
	);

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView.custom(
	itemExtent: 110.0,
	childrenDelegate: delegate,
	),
	),
	);

	expect(delegate.log, equals(<String>['didFinishLayout firstIndex=0 lastIndex=7']));
	delegate.log.clear();

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView.custom(
	itemExtent: 210.0,
	childrenDelegate: delegate,
	),
	),
	);

	expect(delegate.log, equals(<String>['didFinishLayout firstIndex=0 lastIndex=4']));
	delegate.log.clear();

	await tester.drag(find.byType(ListView), const Offset(0.0, -600.0));

	expect(delegate.log, isEmpty);

	await tester.pump();

	expect(delegate.log, equals(<String>['didFinishLayout firstIndex=1 lastIndex=6']));
	delegate.log.clear();
	});

	testWidgets('ListView automatically pad MediaQuery on axis', (WidgetTester tester) async {
	EdgeInsets? innerMediaQueryPadding;

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: MediaQuery(
	data: const MediaQueryData(
	padding: EdgeInsets.all(30.0),
	),
	child: ListView(
	children: <Widget>[
	const Text('top', textDirection: TextDirection.ltr),
	Builder(builder: (BuildContext context) {
	innerMediaQueryPadding = MediaQuery.of(context).padding;
	return Container();
	}),
	],
	),
	),
	),
	);
	// Automatically apply the top/bottom padding into sliver.
	expect(tester.getTopLeft(find.text('top')).dy, 30.0);
	// Leave left/right padding as is for children.
	expect(innerMediaQueryPadding, const EdgeInsets.symmetric(horizontal: 30.0));
	});

	testWidgets('ListView clips if overflow is smaller than cacheExtent', (WidgetTester tester) async {
	// Regression test for https://github.com/flutter/flutter/issues/17426.

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	height: 200.0,
	child: ListView(
	cacheExtent: 500.0,
	children: <Widget>[
	Container(
	height: 90.0,
	),
	Container(
	height: 110.0,
	),
	Container(
	height: 80.0,
	),
	],
	),
	),
	),
	),
	);

	expect(find.byType(Viewport), paints..clipRect());
	});

	testWidgets('ListView does not clips if no overflow', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	height: 200.0,
	child: ListView(
	cacheExtent: 500.0,
	children: const <Widget>[
	SizedBox(
	height: 100.0,
	),
	],
	),
	),
	),
	),
	);

	expect(find.byType(Viewport), isNot(paints..clipRect()));
	});

	testWidgets('ListView (fixed extent) clips if overflow is smaller than cacheExtent', (WidgetTester tester) async {
	// Regression test for https://github.com/flutter/flutter/issues/17426.

	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	height: 200.0,
	child: ListView(
	itemExtent: 100.0,
	cacheExtent: 500.0,
	children: const <Widget>[
	SizedBox(
	height: 100.0,
	),
	SizedBox(
	height: 100.0,
	),
	SizedBox(
	height: 100.0,
	),
	],
	),
	),
	),
	),
	);

	expect(find.byType(Viewport), paints..clipRect());
	});

	testWidgets('ListView (fixed extent) does not clips if no overflow', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	height: 200.0,
	child: ListView(
	itemExtent: 100.0,
	cacheExtent: 500.0,
	children: const <Widget>[
	SizedBox(
	height: 100.0,
	),
	],
	),
	),
	),
	),
	);

	expect(find.byType(Viewport), isNot(paints..clipRect()));
	});

	testWidgets('ListView.horizontal has implicit scrolling by default', (WidgetTester tester) async {
	final SemanticsHandle handle = tester.ensureSemantics();
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	height: 200.0,
	child: ListView(
	scrollDirection: Axis.horizontal,
	itemExtent: 100.0,
	children: const <Widget>[
	SizedBox(
	height: 100.0,
	),
	],
	),
	),
	),
	),
	);
	expect(tester.getSemantics(find.byType(Scrollable)), matchesSemantics(
	children: <Matcher>[
	matchesSemantics(
	children: <Matcher>[
	matchesSemantics(hasImplicitScrolling: true),
	],
	),
	],
	));
	handle.dispose();
	});

	testWidgets('Updates viewport dimensions when scroll direction changes', (WidgetTester tester) async {
	// Regression test for https://github.com/flutter/flutter/issues/43380.
	final ScrollController controller = ScrollController();

	Widget buildListView({ required Axis scrollDirection }) {
	assert(scrollDirection != null);
	return Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: SizedBox(
	height: 200.0,
	width: 100.0,
	child: ListView(
	controller: controller,
	scrollDirection: scrollDirection,
	itemExtent: 50.0,
	children: const <Widget>[
	SizedBox(
	height: 50.0,
	width: 50.0,
	),
	],
	),
	),
	),
	);
	}

	await tester.pumpWidget(buildListView(scrollDirection: Axis.horizontal));
	expect(controller.position.viewportDimension, 100.0);

	await tester.pumpWidget(buildListView(scrollDirection: Axis.vertical));
	expect(controller.position.viewportDimension, 200.0);

	await tester.pumpWidget(buildListView(scrollDirection: Axis.horizontal));
	expect(controller.position.viewportDimension, 100.0);
	});

	testWidgets('ListView respects clipBehavior', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	children: <Widget>[Container(height: 2000.0)],
	),
	),
	);

	// 1st, check that the render object has received the default clip behavior.
	final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
	expect(renderObject.clipBehavior, equals(Clip.hardEdge));

	// 2nd, check that the painting context has received the default clip behavior.
	final TestClipPaintingContext context = TestClipPaintingContext();
	renderObject.paint(context, Offset.zero);
	expect(context.clipBehavior, equals(Clip.hardEdge));

	// 3rd, pump a new widget to check that the render object can update its clip behavior.
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView(
	clipBehavior: Clip.antiAlias,
	children: <Widget>[Container(height: 2000.0)],
	),
	),
	);
	expect(renderObject.clipBehavior, equals(Clip.antiAlias));

	// 4th, check that a non-default clip behavior can be sent to the painting context.
	renderObject.paint(context, Offset.zero);
	expect(context.clipBehavior, equals(Clip.antiAlias));
	});

	testWidgets('ListView.builder respects clipBehavior', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView.builder(
	itemCount: 10,
	itemBuilder: (BuildContext _, int __) => Container(height: 2000.0),
	clipBehavior: Clip.antiAlias,
	),
	),
	);
	final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
	expect(renderObject.clipBehavior, equals(Clip.antiAlias));
	});

	testWidgets('ListView.custom respects clipBehavior', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView.custom(
	childrenDelegate: SliverChildBuilderDelegate(
	(BuildContext context, int index) => Container(height: 2000.0),
	childCount: 1,
	),
	clipBehavior: Clip.antiAlias,
	),
	),
	);
	final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
	expect(renderObject.clipBehavior, equals(Clip.antiAlias));
	});

	testWidgets('ListView.separated respects clipBehavior', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ListView.separated(
	itemCount: 10,
	itemBuilder: (BuildContext _, int __) => Container(height: 2000.0),
	separatorBuilder: (BuildContext _, int __) => const Divider(),
	clipBehavior: Clip.antiAlias,
	),
	),
	);
	final RenderViewport renderObject = tester.allRenderObjects.whereType<RenderViewport>().first;
	expect(renderObject.clipBehavior, equals(Clip.antiAlias));
	});
	}