packages/flutter/test/widgets/slivers_appbar_pinned_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/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';

 void verifyPaintPosition(GlobalKey key, Offset ideal, bool visible) {
   final RenderSliver target = key.currentContext!.findRenderObject()! as RenderSliver;
   expect(target.parent, isA<RenderViewport>());
   final SliverPhysicalParentData parentData = target.parentData! as SliverPhysicalParentData;
   final Offset actual = parentData.paintOffset;
   expect(actual, ideal);
   final SliverGeometry geometry = target.geometry!;
   expect(geometry.visible, visible);
 }

 void verifyActualBoxPosition(WidgetTester tester, Finder finder, int index, Rect ideal) {
   final RenderBox box = tester.renderObjectList<RenderBox>(finder).elementAt(index);
   final Rect rect = Rect.fromPoints(box.localToGlobal(Offset.zero), box.localToGlobal(box.size.bottomRight(Offset.zero)));
   expect(rect, equals(ideal));
 }

 void main() {
   testWidgets('Sliver appbars - pinned', (WidgetTester tester) async {
     const double bigHeight = 550.0;
     GlobalKey key1, key2, key3, key4, key5;
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             BigSliver(key: key1 = GlobalKey(), height: bigHeight),
             SliverPersistentHeader(key: key2 = GlobalKey(), delegate: TestDelegate(), pinned: true),
             SliverPersistentHeader(key: key3 = GlobalKey(), delegate: TestDelegate(), pinned: true),
             BigSliver(key: key4 = GlobalKey(), height: bigHeight),
             BigSliver(key: key5 = GlobalKey(), height: bigHeight),
           ],
         ),
       ),
     );
     final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
     final double max = bigHeight * 3.0 + TestDelegate().maxExtent * 2.0 - 600.0; // 600 is the height of the test viewport
     assert(max < 10000.0);
     expect(max, 1450.0);
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
     position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyPaintPosition(key4, Offset.zero, true);
     verifyPaintPosition(key5, const Offset(0.0, 50.0), true);
   });

   testWidgets('Sliver appbars - toStringDeep of maxExtent that throws', (WidgetTester tester) async {
     final TestDelegateThatCanThrow delegateThatCanThrow = TestDelegateThatCanThrow();
     GlobalKey key;
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             SliverPersistentHeader(key: key = GlobalKey(), delegate: delegateThatCanThrow, pinned: true),
           ],
         ),
       ),
     );
     await tester.pumpAndSettle(const Duration(milliseconds: 10));

     final RenderObject renderObject = key.currentContext!.findRenderObject()!;
     // The delegate must only start throwing immediately before calling
     // toStringDeep to avoid triggering spurious exceptions.
     // If the _RenderSliverPinnedPersistentHeaderForWidgets class was not
     // private it would make more sense to create an instance of it directly.
     delegateThatCanThrow.shouldThrow = true;
     expect(renderObject, hasAGoodToStringDeep);
     expect(
       renderObject.toStringDeep(minLevel: DiagnosticLevel.info),
       equalsIgnoringHashCodes(
         '_RenderSliverPinnedPersistentHeaderForWidgets#00000 relayoutBoundary=up1\n'
         ' │ parentData: paintOffset=Offset(0.0, 0.0) (can use size)\n'
         ' │ constraints: SliverConstraints(AxisDirection.down,\n'
         ' │   GrowthDirection.forward, ScrollDirection.idle, scrollOffset:\n'
         ' │   0.0, remainingPaintExtent: 600.0, crossAxisExtent: 800.0,\n'
         ' │   crossAxisDirection: AxisDirection.right,\n'
         ' │   viewportMainAxisExtent: 600.0, remainingCacheExtent: 850.0,\n'
         ' │   cacheOrigin: 0.0)\n'
         ' │ geometry: SliverGeometry(scrollExtent: 200.0, paintExtent: 200.0,\n'
         ' │   maxPaintExtent: 200.0, hasVisualOverflow: true, cacheExtent:\n'
         ' │   200.0)\n'
         ' │ maxExtent: EXCEPTION (FlutterError)\n'
         ' │ child position: 0.0\n'
         ' │\n'
         ' └─child: RenderConstrainedBox#00000 relayoutBoundary=up2\n'
         '   │ parentData: <none> (can use size)\n'
         '   │ constraints: BoxConstraints(w=800.0, 0.0<=h<=200.0)\n'
         '   │ size: Size(800.0, 200.0)\n'
         '   │ additionalConstraints: BoxConstraints(0.0<=w<=Infinity,\n'
         '   │   100.0<=h<=200.0)\n'
         '   │\n'
         '   └─child: RenderLimitedBox#00000 relayoutBoundary=up3\n'
         '     │ parentData: <none> (can use size)\n'
         '     │ constraints: BoxConstraints(w=800.0, 100.0<=h<=200.0)\n'
         '     │ size: Size(800.0, 200.0)\n'
         '     │ maxWidth: 0.0\n'
         '     │ maxHeight: 0.0\n'
         '     │\n'
         '     └─child: RenderConstrainedBox#00000 relayoutBoundary=up4\n'
         '         parentData: <none> (can use size)\n'
         '         constraints: BoxConstraints(w=800.0, 100.0<=h<=200.0)\n'
         '         size: Size(800.0, 200.0)\n'
         '         additionalConstraints: BoxConstraints(biggest)\n',
       ),
     );
   });

   testWidgets('Sliver appbars - pinned with slow scroll', (WidgetTester tester) async {
     const double bigHeight = 550.0;
     GlobalKey key1, key2, key3, key4, key5;
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             BigSliver(key: key1 = GlobalKey(), height: bigHeight),
             SliverPersistentHeader(key: key2 = GlobalKey(), delegate: TestDelegate(), pinned: true),
             SliverPersistentHeader(key: key3 = GlobalKey(), delegate: TestDelegate(), pinned: true),
             BigSliver(key: key4 = GlobalKey(), height: bigHeight),
             BigSliver(key: key5 = GlobalKey(), height: bigHeight),
           ],
         ),
       ),
     );

     final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
     verifyPaintPosition(key1, Offset.zero, true);
     verifyPaintPosition(key2, const Offset(0.0, 550.0), true);
     verifyPaintPosition(key3, const Offset(0.0, 750.0), false);
     verifyPaintPosition(key4, const Offset(0.0, 950.0), false);
     verifyPaintPosition(key5, const Offset(0.0, 1500.0), false);
     position.animateTo(550.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle();
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 200.0), true);
     verifyPaintPosition(key4, const Offset(0.0, 400.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 950.0), false);
     position.animateTo(600.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 200));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 150.0), true);
     verifyPaintPosition(key4, const Offset(0.0, 350.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 900.0), false);
     position.animateTo(650.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 300));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
     verifyPaintPosition(key4, const Offset(0.0, 300.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 850.0), false);
     position.animateTo(700.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 400));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
     verifyPaintPosition(key4, const Offset(0.0, 250.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 800.0), false);
     position.animateTo(750.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 500));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
     verifyPaintPosition(key4, const Offset(0.0, 200.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 750.0), false);
     position.animateTo(800.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 60));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyPaintPosition(key4, const Offset(0.0, 150.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 700.0), false);
     position.animateTo(850.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 70));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyPaintPosition(key4, const Offset(0.0, 100.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 650.0), false);
     position.animateTo(900.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 80));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyPaintPosition(key4, const Offset(0.0, 50.0), true);
     verifyPaintPosition(key5, const Offset(0.0, 600.0), false);
     position.animateTo(950.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 90));
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 100.0));
     verifyPaintPosition(key4, Offset.zero, true);
     verifyPaintPosition(key5, const Offset(0.0, 550.0), true);
   });

   testWidgets('Sliver appbars - pinned with less overlap', (WidgetTester tester) async {
     const double bigHeight = 650.0;
     GlobalKey key1, key2, key3, key4, key5;
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             BigSliver(key: key1 = GlobalKey(), height: bigHeight),
             SliverPersistentHeader(key: key2 = GlobalKey(), delegate: TestDelegate(), pinned: true),
             SliverPersistentHeader(key: key3 = GlobalKey(), delegate: TestDelegate(), pinned: true),
             BigSliver(key: key4 = GlobalKey(), height: bigHeight),
             BigSliver(key: key5 = GlobalKey(), height: bigHeight),
           ],
         ),
       ),
     );
     final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
     final double max = bigHeight * 3.0 + TestDelegate().maxExtent * 2.0 - 600.0; // 600 is the height of the test viewport
     assert(max < 10000.0);
     expect(max, 1750.0);
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
     position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpAndSettle(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
     verifyPaintPosition(key1, Offset.zero, false);
     verifyPaintPosition(key2, Offset.zero, true);
     verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
     verifyPaintPosition(key4, Offset.zero, false);
     verifyPaintPosition(key5, Offset.zero, true);
   });

   testWidgets('Sliver appbars - overscroll gap is below header', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           physics: const BouncingScrollPhysics(),
           slivers: <Widget>[
             SliverPersistentHeader(delegate: TestDelegate(), pinned: true),
             SliverList(
               delegate: SliverChildListDelegate(<Widget>[
                 const SizedBox(
                   height: 300.0,
                   child: Text('X'),
                 ),
               ]),
             ),
           ],
         ),
       ),
     );

     expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
     expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 200.0));

     final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
     position.jumpTo(-50.0);
     await tester.pump();

     expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
     expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 250.0));

     position.jumpTo(50.0);
     await tester.pump();

     expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
     expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 150.0));

     position.jumpTo(150.0);
     await tester.pump();

     expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
     expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 50.0));
   });
 }

 class TestDelegate extends SliverPersistentHeaderDelegate {
   @override
   double get maxExtent => 200.0;

   @override
   double get minExtent => 100.0;

   @override
   Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
     return Container(constraints: BoxConstraints(minHeight: minExtent, maxHeight: maxExtent));
   }

   @override
   bool shouldRebuild(TestDelegate oldDelegate) => false;
 }

 class TestDelegateThatCanThrow extends SliverPersistentHeaderDelegate {
   bool shouldThrow = false;

   @override
   double get maxExtent {
     return shouldThrow ? throw FlutterError('Unavailable maxExtent') : 200.0;
   }

   @override
   double get minExtent {
     return shouldThrow ? throw FlutterError('Unavailable minExtent') : 100.0;
   }

   @override
   Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
     return Container(constraints: BoxConstraints(minHeight: minExtent, maxHeight: maxExtent));
   }

   @override
   bool shouldRebuild(TestDelegate oldDelegate) => false;
 }


 class RenderBigSliver extends RenderSliver {
   RenderBigSliver(double height) : _height = height;

   double get height => _height;
   double _height;
   set height(double value) {
     if (value == _height)
       return;
     _height = value;
     markNeedsLayout();
   }

   double get paintExtent => (height - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent);

   @override
   void performLayout() {
     geometry = SliverGeometry(
       scrollExtent: height,
       paintExtent: paintExtent,
       maxPaintExtent: height,
     );
   }
 }

 class BigSliver extends LeafRenderObjectWidget {
   const BigSliver({ Key? key, required this.height }) : super(key: key);

   final double height;

   @override
   RenderBigSliver createRenderObject(BuildContext context) {
     return RenderBigSliver(height);
   }

   @override
   void updateRenderObject(BuildContext context, RenderBigSliver renderObject) {
     renderObject.height = height;
   }
 }
	// 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/rendering.dart';
	import 'package:flutter/widgets.dart';
	import 'package:flutter_test/flutter_test.dart';

	void verifyPaintPosition(GlobalKey key, Offset ideal, bool visible) {
	final RenderSliver target = key.currentContext!.findRenderObject()! as RenderSliver;
	expect(target.parent, isA<RenderViewport>());
	final SliverPhysicalParentData parentData = target.parentData! as SliverPhysicalParentData;
	final Offset actual = parentData.paintOffset;
	expect(actual, ideal);
	final SliverGeometry geometry = target.geometry!;
	expect(geometry.visible, visible);
	}

	void verifyActualBoxPosition(WidgetTester tester, Finder finder, int index, Rect ideal) {
	final RenderBox box = tester.renderObjectList<RenderBox>(finder).elementAt(index);
	final Rect rect = Rect.fromPoints(box.localToGlobal(Offset.zero), box.localToGlobal(box.size.bottomRight(Offset.zero)));
	expect(rect, equals(ideal));
	}

	void main() {
	testWidgets('Sliver appbars - pinned', (WidgetTester tester) async {
	const double bigHeight = 550.0;
	GlobalKey key1, key2, key3, key4, key5;
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	BigSliver(key: key1 = GlobalKey(), height: bigHeight),
	SliverPersistentHeader(key: key2 = GlobalKey(), delegate: TestDelegate(), pinned: true),
	SliverPersistentHeader(key: key3 = GlobalKey(), delegate: TestDelegate(), pinned: true),
	BigSliver(key: key4 = GlobalKey(), height: bigHeight),
	BigSliver(key: key5 = GlobalKey(), height: bigHeight),
	],
	),
	),
	);
	final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
	final double max = bigHeight * 3.0 + TestDelegate().maxExtent * 2.0 - 600.0; // 600 is the height of the test viewport
	assert(max < 10000.0);
	expect(max, 1450.0);
	expect(position.pixels, 0.0);
	expect(position.minScrollExtent, 0.0);
	expect(position.maxScrollExtent, max);
	position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 10));
	expect(position.pixels, max);
	expect(position.minScrollExtent, 0.0);
	expect(position.maxScrollExtent, max);
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyPaintPosition(key4, Offset.zero, true);
	verifyPaintPosition(key5, const Offset(0.0, 50.0), true);
	});

	testWidgets('Sliver appbars - toStringDeep of maxExtent that throws', (WidgetTester tester) async {
	final TestDelegateThatCanThrow delegateThatCanThrow = TestDelegateThatCanThrow();
	GlobalKey key;
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	SliverPersistentHeader(key: key = GlobalKey(), delegate: delegateThatCanThrow, pinned: true),
	],
	),
	),
	);
	await tester.pumpAndSettle(const Duration(milliseconds: 10));

	final RenderObject renderObject = key.currentContext!.findRenderObject()!;
	// The delegate must only start throwing immediately before calling
	// toStringDeep to avoid triggering spurious exceptions.
	// If the _RenderSliverPinnedPersistentHeaderForWidgets class was not
	// private it would make more sense to create an instance of it directly.
	delegateThatCanThrow.shouldThrow = true;
	expect(renderObject, hasAGoodToStringDeep);
	expect(
	renderObject.toStringDeep(minLevel: DiagnosticLevel.info),
	equalsIgnoringHashCodes(
	'_RenderSliverPinnedPersistentHeaderForWidgets#00000 relayoutBoundary=up1\n'
	' │ parentData: paintOffset=Offset(0.0, 0.0) (can use size)\n'
	' │ constraints: SliverConstraints(AxisDirection.down,\n'
	' │ GrowthDirection.forward, ScrollDirection.idle, scrollOffset:\n'
	' │ 0.0, remainingPaintExtent: 600.0, crossAxisExtent: 800.0,\n'
	' │ crossAxisDirection: AxisDirection.right,\n'
	' │ viewportMainAxisExtent: 600.0, remainingCacheExtent: 850.0,\n'
	' │ cacheOrigin: 0.0)\n'
	' │ geometry: SliverGeometry(scrollExtent: 200.0, paintExtent: 200.0,\n'
	' │ maxPaintExtent: 200.0, hasVisualOverflow: true, cacheExtent:\n'
	' │ 200.0)\n'
	' │ maxExtent: EXCEPTION (FlutterError)\n'
	' │ child position: 0.0\n'
	' │\n'
	' └─child: RenderConstrainedBox#00000 relayoutBoundary=up2\n'
	' │ parentData: <none> (can use size)\n'
	' │ constraints: BoxConstraints(w=800.0, 0.0<=h<=200.0)\n'
	' │ size: Size(800.0, 200.0)\n'
	' │ additionalConstraints: BoxConstraints(0.0<=w<=Infinity,\n'
	' │ 100.0<=h<=200.0)\n'
	' │\n'
	' └─child: RenderLimitedBox#00000 relayoutBoundary=up3\n'
	' │ parentData: <none> (can use size)\n'
	' │ constraints: BoxConstraints(w=800.0, 100.0<=h<=200.0)\n'
	' │ size: Size(800.0, 200.0)\n'
	' │ maxWidth: 0.0\n'
	' │ maxHeight: 0.0\n'
	' │\n'
	' └─child: RenderConstrainedBox#00000 relayoutBoundary=up4\n'
	' parentData: <none> (can use size)\n'
	' constraints: BoxConstraints(w=800.0, 100.0<=h<=200.0)\n'
	' size: Size(800.0, 200.0)\n'
	' additionalConstraints: BoxConstraints(biggest)\n',
	),
	);
	});

	testWidgets('Sliver appbars - pinned with slow scroll', (WidgetTester tester) async {
	const double bigHeight = 550.0;
	GlobalKey key1, key2, key3, key4, key5;
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	BigSliver(key: key1 = GlobalKey(), height: bigHeight),
	SliverPersistentHeader(key: key2 = GlobalKey(), delegate: TestDelegate(), pinned: true),
	SliverPersistentHeader(key: key3 = GlobalKey(), delegate: TestDelegate(), pinned: true),
	BigSliver(key: key4 = GlobalKey(), height: bigHeight),
	BigSliver(key: key5 = GlobalKey(), height: bigHeight),
	],
	),
	),
	);

	final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
	verifyPaintPosition(key1, Offset.zero, true);
	verifyPaintPosition(key2, const Offset(0.0, 550.0), true);
	verifyPaintPosition(key3, const Offset(0.0, 750.0), false);
	verifyPaintPosition(key4, const Offset(0.0, 950.0), false);
	verifyPaintPosition(key5, const Offset(0.0, 1500.0), false);
	position.animateTo(550.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle();
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 200.0), true);
	verifyPaintPosition(key4, const Offset(0.0, 400.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 950.0), false);
	position.animateTo(600.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 200));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 150.0), true);
	verifyPaintPosition(key4, const Offset(0.0, 350.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 900.0), false);
	position.animateTo(650.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 300));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
	verifyPaintPosition(key4, const Offset(0.0, 300.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 850.0), false);
	position.animateTo(700.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 400));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
	verifyPaintPosition(key4, const Offset(0.0, 250.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 800.0), false);
	position.animateTo(750.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 500));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
	verifyPaintPosition(key4, const Offset(0.0, 200.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 750.0), false);
	position.animateTo(800.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 60));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyPaintPosition(key4, const Offset(0.0, 150.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 700.0), false);
	position.animateTo(850.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 70));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyPaintPosition(key4, const Offset(0.0, 100.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 650.0), false);
	position.animateTo(900.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 80));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyPaintPosition(key4, const Offset(0.0, 50.0), true);
	verifyPaintPosition(key5, const Offset(0.0, 600.0), false);
	position.animateTo(950.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 90));
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyActualBoxPosition(tester, find.byType(Container), 1, const Rect.fromLTWH(0.0, 100.0, 800.0, 100.0));
	verifyPaintPosition(key4, Offset.zero, true);
	verifyPaintPosition(key5, const Offset(0.0, 550.0), true);
	});

	testWidgets('Sliver appbars - pinned with less overlap', (WidgetTester tester) async {
	const double bigHeight = 650.0;
	GlobalKey key1, key2, key3, key4, key5;
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	BigSliver(key: key1 = GlobalKey(), height: bigHeight),
	SliverPersistentHeader(key: key2 = GlobalKey(), delegate: TestDelegate(), pinned: true),
	SliverPersistentHeader(key: key3 = GlobalKey(), delegate: TestDelegate(), pinned: true),
	BigSliver(key: key4 = GlobalKey(), height: bigHeight),
	BigSliver(key: key5 = GlobalKey(), height: bigHeight),
	],
	),
	),
	);
	final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
	final double max = bigHeight * 3.0 + TestDelegate().maxExtent * 2.0 - 600.0; // 600 is the height of the test viewport
	assert(max < 10000.0);
	expect(max, 1750.0);
	expect(position.pixels, 0.0);
	expect(position.minScrollExtent, 0.0);
	expect(position.maxScrollExtent, max);
	position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
	await tester.pumpAndSettle(const Duration(milliseconds: 10));
	expect(position.pixels, max);
	expect(position.minScrollExtent, 0.0);
	expect(position.maxScrollExtent, max);
	verifyPaintPosition(key1, Offset.zero, false);
	verifyPaintPosition(key2, Offset.zero, true);
	verifyPaintPosition(key3, const Offset(0.0, 100.0), true);
	verifyPaintPosition(key4, Offset.zero, false);
	verifyPaintPosition(key5, Offset.zero, true);
	});

	testWidgets('Sliver appbars - overscroll gap is below header', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	physics: const BouncingScrollPhysics(),
	slivers: <Widget>[
	SliverPersistentHeader(delegate: TestDelegate(), pinned: true),
	SliverList(
	delegate: SliverChildListDelegate(<Widget>[
	const SizedBox(
	height: 300.0,
	child: Text('X'),
	),
	]),
	),
	],
	),
	),
	);

	expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
	expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 200.0));

	final ScrollPosition position = tester.state<ScrollableState>(find.byType(Scrollable)).position;
	position.jumpTo(-50.0);
	await tester.pump();

	expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
	expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 250.0));

	position.jumpTo(50.0);
	await tester.pump();

	expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
	expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 150.0));

	position.jumpTo(150.0);
	await tester.pump();

	expect(tester.getTopLeft(find.byType(Container)), Offset.zero);
	expect(tester.getTopLeft(find.text('X')), const Offset(0.0, 50.0));
	});
	}

	class TestDelegate extends SliverPersistentHeaderDelegate {
	@override
	double get maxExtent => 200.0;

	@override
	double get minExtent => 100.0;

	@override
	Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
	return Container(constraints: BoxConstraints(minHeight: minExtent, maxHeight: maxExtent));
	}

	@override
	bool shouldRebuild(TestDelegate oldDelegate) => false;
	}

	class TestDelegateThatCanThrow extends SliverPersistentHeaderDelegate {
	bool shouldThrow = false;

	@override
	double get maxExtent {
	return shouldThrow ? throw FlutterError('Unavailable maxExtent') : 200.0;
	}

	@override
	double get minExtent {
	return shouldThrow ? throw FlutterError('Unavailable minExtent') : 100.0;
	}

	@override
	Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
	return Container(constraints: BoxConstraints(minHeight: minExtent, maxHeight: maxExtent));
	}

	@override
	bool shouldRebuild(TestDelegate oldDelegate) => false;
	}


	class RenderBigSliver extends RenderSliver {
	RenderBigSliver(double height) : _height = height;

	double get height => _height;
	double _height;
	set height(double value) {
	if (value == _height)
	return;
	_height = value;
	markNeedsLayout();
	}

	double get paintExtent => (height - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent);

	@override
	void performLayout() {
	geometry = SliverGeometry(
	scrollExtent: height,
	paintExtent: paintExtent,
	maxPaintExtent: height,
	);
	}
	}

	class BigSliver extends LeafRenderObjectWidget {
	const BigSliver({ Key? key, required this.height }) : super(key: key);

	final double height;

	@override
	RenderBigSliver createRenderObject(BuildContext context) {
	return RenderBigSliver(height);
	}

	@override
	void updateRenderObject(BuildContext context, RenderBigSliver renderObject) {
	renderObject.height = height;
	}
	}