packages/animations/test/fade_through_transition_test.dart - mirrors/packages - Git at Google

 // Copyright 2013 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:animations/src/fade_through_transition.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';

 void main() {
   testWidgets(
       'FadeThroughPageTransitionsBuilder builds a FadeThroughTransition',
       (WidgetTester tester) async {
     final AnimationController animation = AnimationController(
       vsync: const TestVSync(),
     );
     final AnimationController secondaryAnimation = AnimationController(
       vsync: const TestVSync(),
     );

     await tester.pumpWidget(
         const FadeThroughPageTransitionsBuilder().buildTransitions<void>(
       null,
       null,
       animation,
       secondaryAnimation,
       const Placeholder(),
     ));

     expect(find.byType(FadeThroughTransition), findsOneWidget);
   });

   testWidgets('FadeThroughTransition runs forward',
       (WidgetTester tester) async {
     final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
     const String bottomRoute = '/';
     const String topRoute = '/a';

     await tester.pumpWidget(
       _TestWidget(
         navigatorKey: navigator,
       ),
     );
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 1.0);
     expect(find.text(topRoute), findsNothing);

     navigator.currentState!.pushNamed(topRoute);
     await tester.pump();
     await tester.pump();

     // Bottom route is full size and fully visible.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 1.0);
     // top route is at 95% of full size and not visible yet.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 0.92);
     expect(_getOpacity(topRoute, tester), 0.0);

     // Jump to half-way through the fade out (total duration is 300ms, 6/12th of
     // that are fade out, so half-way is 300 * 6/12 / 2 = 45ms.
     await tester.pump(const Duration(milliseconds: 45));
     // Bottom route is fading out.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     final double bottomOpacity = _getOpacity(bottomRoute, tester);
     expect(bottomOpacity, lessThan(1.0));
     expect(bottomOpacity, greaterThan(0.0));
     // Top route is still invisible.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 0.92);
     expect(_getOpacity(topRoute, tester), 0.0);

     // Let's jump to the end of the fade-out.
     await tester.pump(const Duration(milliseconds: 45));
     // Bottom route is completely faded out.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 0.0);
     // Top route is still invisible.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 0.92);
     expect(_getOpacity(topRoute, tester), 0.0);

     // Let's jump to the middle of the fade-in.
     await tester.pump(const Duration(milliseconds: 105));
     // Bottom route is not visible.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 0.0);
     // Top route is fading/scaling in.
     expect(find.text(topRoute), findsOneWidget);
     final double topScale = _getScale(topRoute, tester);
     final double topOpacity = _getOpacity(topRoute, tester);
     expect(topScale, greaterThan(0.92));
     expect(topScale, lessThan(1.0));
     expect(topOpacity, greaterThan(0.0));
     expect(topOpacity, lessThan(1.0));

     // Let's jump to the end of the animation.
     await tester.pump(const Duration(milliseconds: 105));
     // Bottom route is not visible.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 0.0);
     // Top route fully scaled in and visible.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     expect(_getOpacity(topRoute, tester), 1.0);

     await tester.pump(const Duration(milliseconds: 1));
     expect(find.text(bottomRoute), findsNothing);
     expect(find.text(topRoute), findsOneWidget);
   });

   testWidgets('FadeThroughTransition runs backwards',
       (WidgetTester tester) async {
     final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
     const String bottomRoute = '/';
     const String topRoute = '/a';

     await tester.pumpWidget(
       _TestWidget(
         navigatorKey: navigator,
       ),
     );
     navigator.currentState!.pushNamed('/a');
     await tester.pumpAndSettle();

     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     expect(_getOpacity(topRoute, tester), 1.0);
     expect(find.text(bottomRoute), findsNothing);

     navigator.currentState!.pop();
     await tester.pump();

     // Top route is full size and fully visible.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     expect(_getOpacity(topRoute, tester), 1.0);
     // Bottom route is at 95% of full size and not visible yet.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 0.92);
     expect(_getOpacity(bottomRoute, tester), 0.0);

     // Jump to half-way through the fade out (total duration is 300ms, 6/12th of
     // that are fade out, so half-way is 300 * 6/12 / 2 = 45ms.
     await tester.pump(const Duration(milliseconds: 45));
     // Bottom route is fading out.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     final double topOpacity = _getOpacity(topRoute, tester);
     expect(topOpacity, lessThan(1.0));
     expect(topOpacity, greaterThan(0.0));
     // Top route is still invisible.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 0.92);
     expect(_getOpacity(bottomRoute, tester), 0.0);

     // Let's jump to the end of the fade-out.
     await tester.pump(const Duration(milliseconds: 45));
     // Bottom route is completely faded out.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     expect(_getOpacity(topRoute, tester), 0.0);
     // Top route is still invisible.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(
       _getScale(bottomRoute, tester),
       moreOrLessEquals(0.92, epsilon: 0.005),
     );
     expect(
       _getOpacity(bottomRoute, tester),
       moreOrLessEquals(0.0, epsilon: 0.005),
     );

     // Let's jump to the middle of the fade-in.
     await tester.pump(const Duration(milliseconds: 105));
     // Bottom route is not visible.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     expect(_getOpacity(topRoute, tester), 0.0);
     // Top route is fading/scaling in.
     expect(find.text(bottomRoute), findsOneWidget);
     final double bottomScale = _getScale(bottomRoute, tester);
     final double bottomOpacity = _getOpacity(bottomRoute, tester);
     expect(bottomScale, greaterThan(0.96));
     expect(bottomScale, lessThan(1.0));
     expect(bottomOpacity, greaterThan(0.1));
     expect(bottomOpacity, lessThan(1.0));

     // Let's jump to the end of the animation.
     await tester.pump(const Duration(milliseconds: 105));
     // Bottom route is not visible.
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 1.0);
     expect(_getOpacity(topRoute, tester), 0.0);
     // Top route fully scaled in and visible.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 1.0);

     await tester.pump(const Duration(milliseconds: 1));
     expect(find.text(topRoute), findsNothing);
     expect(find.text(bottomRoute), findsOneWidget);
   });

   testWidgets('FadeThroughTransition does not jump when interrupted',
       (WidgetTester tester) async {
     final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
     const String bottomRoute = '/';
     const String topRoute = '/a';

     await tester.pumpWidget(
       _TestWidget(
         navigatorKey: navigator,
       ),
     );
     expect(find.text(bottomRoute), findsOneWidget);
     expect(find.text(topRoute), findsNothing);

     navigator.currentState!.pushNamed(topRoute);
     await tester.pump();

     // Jump to halfway point of transition.
     await tester.pump(const Duration(milliseconds: 150));
     // Bottom route is fully faded out.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 0.0);
     // Top route is fading/scaling in.
     expect(find.text(topRoute), findsOneWidget);
     final double topScale = _getScale(topRoute, tester);
     final double topOpacity = _getOpacity(topRoute, tester);
     expect(topScale, greaterThan(0.92));
     expect(topScale, lessThan(1.0));
     expect(topOpacity, greaterThan(0.0));
     expect(topOpacity, lessThan(1.0));

     // Interrupt the transition with a pop.
     navigator.currentState!.pop();
     await tester.pump();
     // Noting changed.
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 0.0);
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), topScale);
     expect(_getOpacity(topRoute, tester), topOpacity);

     // Jump to the halfway point.
     await tester.pump(const Duration(milliseconds: 75));
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     final double bottomOpacity = _getOpacity(bottomRoute, tester);
     expect(bottomOpacity, greaterThan(0.0));
     expect(bottomOpacity, lessThan(1.0));
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), lessThan(topScale));
     expect(_getOpacity(topRoute, tester), lessThan(topOpacity));

     // Jump to the end.
     await tester.pump(const Duration(milliseconds: 75));
     expect(find.text(bottomRoute), findsOneWidget);
     expect(_getScale(bottomRoute, tester), 1.0);
     expect(_getOpacity(bottomRoute, tester), 1.0);
     expect(find.text(topRoute), findsOneWidget);
     expect(_getScale(topRoute, tester), 0.92);
     expect(_getOpacity(topRoute, tester), 0.0);

     await tester.pump(const Duration(milliseconds: 1));
     expect(find.text(topRoute), findsNothing);
     expect(find.text(bottomRoute), findsOneWidget);
   });

   testWidgets('State is not lost when transitioning',
       (WidgetTester tester) async {
     final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
     const String bottomRoute = '/';
     const String topRoute = '/a';

     await tester.pumpWidget(
       _TestWidget(
         navigatorKey: navigator,
         contentBuilder: (RouteSettings settings) {
           return _StatefulTestWidget(
             key: ValueKey<String?>(settings.name),
             name: settings.name,
           );
         },
       ),
     );

     final _StatefulTestWidgetState bottomState =
         tester.state(find.byKey(const ValueKey<String?>(bottomRoute)));
     expect(bottomState.widget.name, bottomRoute);

     navigator.currentState!.pushNamed(topRoute);
     await tester.pump();
     await tester.pump();

     expect(
       tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
       bottomState,
     );
     final _StatefulTestWidgetState topState = tester.state(
       find.byKey(const ValueKey<String?>(topRoute)),
     );
     expect(topState.widget.name, topRoute);

     await tester.pump(const Duration(milliseconds: 150));
     expect(
       tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
       bottomState,
     );
     expect(
       tester.state(find.byKey(const ValueKey<String?>(topRoute))),
       topState,
     );

     await tester.pumpAndSettle();
     expect(
       tester.state(find.byKey(
         const ValueKey<String?>(bottomRoute),
         skipOffstage: false,
       )),
       bottomState,
     );
     expect(
       tester.state(find.byKey(const ValueKey<String?>(topRoute))),
       topState,
     );

     navigator.currentState!.pop();
     await tester.pump();

     expect(
       tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
       bottomState,
     );
     expect(
       tester.state(find.byKey(const ValueKey<String?>(topRoute))),
       topState,
     );

     await tester.pump(const Duration(milliseconds: 150));
     expect(
       tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
       bottomState,
     );
     expect(
       tester.state(find.byKey(const ValueKey<String?>(topRoute))),
       topState,
     );

     await tester.pumpAndSettle();
     expect(
       tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
       bottomState,
     );
     expect(find.byKey(const ValueKey<String?>(topRoute)), findsNothing);
   });

   testWidgets('should keep state', (WidgetTester tester) async {
     final AnimationController animation = AnimationController(
       vsync: const TestVSync(),
       duration: const Duration(milliseconds: 300),
     );
     final AnimationController secondaryAnimation = AnimationController(
       vsync: const TestVSync(),
       duration: const Duration(milliseconds: 300),
     );
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
       child: Center(
         child: FadeThroughTransition(
           animation: animation,
           secondaryAnimation: secondaryAnimation,
           child: const _StatefulTestWidget(name: 'Foo'),
         ),
       ),
     ));
     final State<StatefulWidget> state = tester.state(
       find.byType(_StatefulTestWidget),
     );
     expect(state, isNotNull);

     animation.forward();
     await tester.pump();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pumpAndSettle();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));

     secondaryAnimation.forward();
     await tester.pump();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pumpAndSettle();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));

     secondaryAnimation.reverse();
     await tester.pump();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pumpAndSettle();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));

     animation.reverse();
     await tester.pump();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pump(const Duration(milliseconds: 150));
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
     await tester.pumpAndSettle();
     expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
   });
 }

 double _getOpacity(String key, WidgetTester tester) {
   final Finder finder = find.ancestor(
     of: find.byKey(ValueKey<String?>(key)),
     matching: find.byType(FadeTransition),
   );
   return tester.widgetList(finder).fold<double>(1.0, (double a, Widget widget) {
     final FadeTransition transition = widget as FadeTransition;
     return a * transition.opacity.value;
   });
 }

 double _getScale(String key, WidgetTester tester) {
   final Finder finder = find.ancestor(
     of: find.byKey(ValueKey<String?>(key)),
     matching: find.byType(ScaleTransition),
   );
   return tester.widgetList(finder).fold<double>(1.0, (double a, Widget widget) {
     final ScaleTransition transition = widget as ScaleTransition;
     return a * transition.scale.value;
   });
 }

 class _TestWidget extends StatelessWidget {
   const _TestWidget({this.navigatorKey, this.contentBuilder});

   final Key? navigatorKey;
   final _ContentBuilder? contentBuilder;

   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       navigatorKey: navigatorKey as GlobalKey<NavigatorState>?,
       theme: ThemeData(
         platform: TargetPlatform.android,
         pageTransitionsTheme: const PageTransitionsTheme(
           builders: <TargetPlatform, PageTransitionsBuilder>{
             TargetPlatform.android: FadeThroughPageTransitionsBuilder(),
           },
         ),
       ),
       onGenerateRoute: (RouteSettings settings) {
         return MaterialPageRoute<void>(
           settings: settings,
           builder: (BuildContext context) {
             return contentBuilder != null
                 ? contentBuilder!(settings)
                 : Center(
                     key: ValueKey<String?>(settings.name),
                     child: Text(settings.name!),
                   );
           },
         );
       },
     );
   }
 }

 class _StatefulTestWidget extends StatefulWidget {
   const _StatefulTestWidget({Key? key, this.name}) : super(key: key);

   final String? name;

   @override
   State<_StatefulTestWidget> createState() => _StatefulTestWidgetState();
 }

 class _StatefulTestWidgetState extends State<_StatefulTestWidget> {
   @override
   Widget build(BuildContext context) {
     return Text(widget.name!);
   }
 }

 typedef _ContentBuilder = Widget Function(RouteSettings settings);
	// Copyright 2013 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:animations/src/fade_through_transition.dart';
	import 'package:flutter/material.dart';
	import 'package:flutter_test/flutter_test.dart';

	void main() {
	testWidgets(
	'FadeThroughPageTransitionsBuilder builds a FadeThroughTransition',
	(WidgetTester tester) async {
	final AnimationController animation = AnimationController(
	vsync: const TestVSync(),
	);
	final AnimationController secondaryAnimation = AnimationController(
	vsync: const TestVSync(),
	);

	await tester.pumpWidget(
	const FadeThroughPageTransitionsBuilder().buildTransitions<void>(
	null,
	null,
	animation,
	secondaryAnimation,
	const Placeholder(),
	));

	expect(find.byType(FadeThroughTransition), findsOneWidget);
	});

	testWidgets('FadeThroughTransition runs forward',
	(WidgetTester tester) async {
	final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
	const String bottomRoute = '/';
	const String topRoute = '/a';

	await tester.pumpWidget(
	_TestWidget(
	navigatorKey: navigator,
	),
	);
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 1.0);
	expect(find.text(topRoute), findsNothing);

	navigator.currentState!.pushNamed(topRoute);
	await tester.pump();
	await tester.pump();

	// Bottom route is full size and fully visible.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 1.0);
	// top route is at 95% of full size and not visible yet.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 0.92);
	expect(_getOpacity(topRoute, tester), 0.0);

	// Jump to half-way through the fade out (total duration is 300ms, 6/12th of
	// that are fade out, so half-way is 300 * 6/12 / 2 = 45ms.
	await tester.pump(const Duration(milliseconds: 45));
	// Bottom route is fading out.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	final double bottomOpacity = _getOpacity(bottomRoute, tester);
	expect(bottomOpacity, lessThan(1.0));
	expect(bottomOpacity, greaterThan(0.0));
	// Top route is still invisible.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 0.92);
	expect(_getOpacity(topRoute, tester), 0.0);

	// Let's jump to the end of the fade-out.
	await tester.pump(const Duration(milliseconds: 45));
	// Bottom route is completely faded out.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 0.0);
	// Top route is still invisible.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 0.92);
	expect(_getOpacity(topRoute, tester), 0.0);

	// Let's jump to the middle of the fade-in.
	await tester.pump(const Duration(milliseconds: 105));
	// Bottom route is not visible.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 0.0);
	// Top route is fading/scaling in.
	expect(find.text(topRoute), findsOneWidget);
	final double topScale = _getScale(topRoute, tester);
	final double topOpacity = _getOpacity(topRoute, tester);
	expect(topScale, greaterThan(0.92));
	expect(topScale, lessThan(1.0));
	expect(topOpacity, greaterThan(0.0));
	expect(topOpacity, lessThan(1.0));

	// Let's jump to the end of the animation.
	await tester.pump(const Duration(milliseconds: 105));
	// Bottom route is not visible.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 0.0);
	// Top route fully scaled in and visible.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	expect(_getOpacity(topRoute, tester), 1.0);

	await tester.pump(const Duration(milliseconds: 1));
	expect(find.text(bottomRoute), findsNothing);
	expect(find.text(topRoute), findsOneWidget);
	});

	testWidgets('FadeThroughTransition runs backwards',
	(WidgetTester tester) async {
	final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
	const String bottomRoute = '/';
	const String topRoute = '/a';

	await tester.pumpWidget(
	_TestWidget(
	navigatorKey: navigator,
	),
	);
	navigator.currentState!.pushNamed('/a');
	await tester.pumpAndSettle();

	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	expect(_getOpacity(topRoute, tester), 1.0);
	expect(find.text(bottomRoute), findsNothing);

	navigator.currentState!.pop();
	await tester.pump();

	// Top route is full size and fully visible.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	expect(_getOpacity(topRoute, tester), 1.0);
	// Bottom route is at 95% of full size and not visible yet.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 0.92);
	expect(_getOpacity(bottomRoute, tester), 0.0);

	// Jump to half-way through the fade out (total duration is 300ms, 6/12th of
	// that are fade out, so half-way is 300 * 6/12 / 2 = 45ms.
	await tester.pump(const Duration(milliseconds: 45));
	// Bottom route is fading out.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	final double topOpacity = _getOpacity(topRoute, tester);
	expect(topOpacity, lessThan(1.0));
	expect(topOpacity, greaterThan(0.0));
	// Top route is still invisible.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 0.92);
	expect(_getOpacity(bottomRoute, tester), 0.0);

	// Let's jump to the end of the fade-out.
	await tester.pump(const Duration(milliseconds: 45));
	// Bottom route is completely faded out.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	expect(_getOpacity(topRoute, tester), 0.0);
	// Top route is still invisible.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(
	_getScale(bottomRoute, tester),
	moreOrLessEquals(0.92, epsilon: 0.005),
	);
	expect(
	_getOpacity(bottomRoute, tester),
	moreOrLessEquals(0.0, epsilon: 0.005),
	);

	// Let's jump to the middle of the fade-in.
	await tester.pump(const Duration(milliseconds: 105));
	// Bottom route is not visible.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	expect(_getOpacity(topRoute, tester), 0.0);
	// Top route is fading/scaling in.
	expect(find.text(bottomRoute), findsOneWidget);
	final double bottomScale = _getScale(bottomRoute, tester);
	final double bottomOpacity = _getOpacity(bottomRoute, tester);
	expect(bottomScale, greaterThan(0.96));
	expect(bottomScale, lessThan(1.0));
	expect(bottomOpacity, greaterThan(0.1));
	expect(bottomOpacity, lessThan(1.0));

	// Let's jump to the end of the animation.
	await tester.pump(const Duration(milliseconds: 105));
	// Bottom route is not visible.
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 1.0);
	expect(_getOpacity(topRoute, tester), 0.0);
	// Top route fully scaled in and visible.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 1.0);

	await tester.pump(const Duration(milliseconds: 1));
	expect(find.text(topRoute), findsNothing);
	expect(find.text(bottomRoute), findsOneWidget);
	});

	testWidgets('FadeThroughTransition does not jump when interrupted',
	(WidgetTester tester) async {
	final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
	const String bottomRoute = '/';
	const String topRoute = '/a';

	await tester.pumpWidget(
	_TestWidget(
	navigatorKey: navigator,
	),
	);
	expect(find.text(bottomRoute), findsOneWidget);
	expect(find.text(topRoute), findsNothing);

	navigator.currentState!.pushNamed(topRoute);
	await tester.pump();

	// Jump to halfway point of transition.
	await tester.pump(const Duration(milliseconds: 150));
	// Bottom route is fully faded out.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 0.0);
	// Top route is fading/scaling in.
	expect(find.text(topRoute), findsOneWidget);
	final double topScale = _getScale(topRoute, tester);
	final double topOpacity = _getOpacity(topRoute, tester);
	expect(topScale, greaterThan(0.92));
	expect(topScale, lessThan(1.0));
	expect(topOpacity, greaterThan(0.0));
	expect(topOpacity, lessThan(1.0));

	// Interrupt the transition with a pop.
	navigator.currentState!.pop();
	await tester.pump();
	// Noting changed.
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 0.0);
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), topScale);
	expect(_getOpacity(topRoute, tester), topOpacity);

	// Jump to the halfway point.
	await tester.pump(const Duration(milliseconds: 75));
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	final double bottomOpacity = _getOpacity(bottomRoute, tester);
	expect(bottomOpacity, greaterThan(0.0));
	expect(bottomOpacity, lessThan(1.0));
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), lessThan(topScale));
	expect(_getOpacity(topRoute, tester), lessThan(topOpacity));

	// Jump to the end.
	await tester.pump(const Duration(milliseconds: 75));
	expect(find.text(bottomRoute), findsOneWidget);
	expect(_getScale(bottomRoute, tester), 1.0);
	expect(_getOpacity(bottomRoute, tester), 1.0);
	expect(find.text(topRoute), findsOneWidget);
	expect(_getScale(topRoute, tester), 0.92);
	expect(_getOpacity(topRoute, tester), 0.0);

	await tester.pump(const Duration(milliseconds: 1));
	expect(find.text(topRoute), findsNothing);
	expect(find.text(bottomRoute), findsOneWidget);
	});

	testWidgets('State is not lost when transitioning',
	(WidgetTester tester) async {
	final GlobalKey<NavigatorState> navigator = GlobalKey<NavigatorState>();
	const String bottomRoute = '/';
	const String topRoute = '/a';

	await tester.pumpWidget(
	_TestWidget(
	navigatorKey: navigator,
	contentBuilder: (RouteSettings settings) {
	return _StatefulTestWidget(
	key: ValueKey<String?>(settings.name),
	name: settings.name,
	);
	},
	),
	);

	final _StatefulTestWidgetState bottomState =
	tester.state(find.byKey(const ValueKey<String?>(bottomRoute)));
	expect(bottomState.widget.name, bottomRoute);

	navigator.currentState!.pushNamed(topRoute);
	await tester.pump();
	await tester.pump();

	expect(
	tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
	bottomState,
	);
	final _StatefulTestWidgetState topState = tester.state(
	find.byKey(const ValueKey<String?>(topRoute)),
	);
	expect(topState.widget.name, topRoute);

	await tester.pump(const Duration(milliseconds: 150));
	expect(
	tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
	bottomState,
	);
	expect(
	tester.state(find.byKey(const ValueKey<String?>(topRoute))),
	topState,
	);

	await tester.pumpAndSettle();
	expect(
	tester.state(find.byKey(
	const ValueKey<String?>(bottomRoute),
	skipOffstage: false,
	)),
	bottomState,
	);
	expect(
	tester.state(find.byKey(const ValueKey<String?>(topRoute))),
	topState,
	);

	navigator.currentState!.pop();
	await tester.pump();

	expect(
	tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
	bottomState,
	);
	expect(
	tester.state(find.byKey(const ValueKey<String?>(topRoute))),
	topState,
	);

	await tester.pump(const Duration(milliseconds: 150));
	expect(
	tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
	bottomState,
	);
	expect(
	tester.state(find.byKey(const ValueKey<String?>(topRoute))),
	topState,
	);

	await tester.pumpAndSettle();
	expect(
	tester.state(find.byKey(const ValueKey<String?>(bottomRoute))),
	bottomState,
	);
	expect(find.byKey(const ValueKey<String?>(topRoute)), findsNothing);
	});

	testWidgets('should keep state', (WidgetTester tester) async {
	final AnimationController animation = AnimationController(
	vsync: const TestVSync(),
	duration: const Duration(milliseconds: 300),
	);
	final AnimationController secondaryAnimation = AnimationController(
	vsync: const TestVSync(),
	duration: const Duration(milliseconds: 300),
	);
	await tester.pumpWidget(Directionality(
	textDirection: TextDirection.ltr,
	child: Center(
	child: FadeThroughTransition(
	animation: animation,
	secondaryAnimation: secondaryAnimation,
	child: const _StatefulTestWidget(name: 'Foo'),
	),
	),
	));
	final State<StatefulWidget> state = tester.state(
	find.byType(_StatefulTestWidget),
	);
	expect(state, isNotNull);

	animation.forward();
	await tester.pump();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pumpAndSettle();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));

	secondaryAnimation.forward();
	await tester.pump();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pumpAndSettle();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));

	secondaryAnimation.reverse();
	await tester.pump();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pumpAndSettle();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));

	animation.reverse();
	await tester.pump();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pump(const Duration(milliseconds: 150));
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	await tester.pumpAndSettle();
	expect(state, same(tester.state(find.byType(_StatefulTestWidget))));
	});
	}

	double _getOpacity(String key, WidgetTester tester) {
	final Finder finder = find.ancestor(
	of: find.byKey(ValueKey<String?>(key)),
	matching: find.byType(FadeTransition),
	);
	return tester.widgetList(finder).fold<double>(1.0, (double a, Widget widget) {
	final FadeTransition transition = widget as FadeTransition;
	return a * transition.opacity.value;
	});
	}

	double _getScale(String key, WidgetTester tester) {
	final Finder finder = find.ancestor(
	of: find.byKey(ValueKey<String?>(key)),
	matching: find.byType(ScaleTransition),
	);
	return tester.widgetList(finder).fold<double>(1.0, (double a, Widget widget) {
	final ScaleTransition transition = widget as ScaleTransition;
	return a * transition.scale.value;
	});
	}

	class _TestWidget extends StatelessWidget {
	const _TestWidget({this.navigatorKey, this.contentBuilder});

	final Key? navigatorKey;
	final _ContentBuilder? contentBuilder;

	@override
	Widget build(BuildContext context) {
	return MaterialApp(
	navigatorKey: navigatorKey as GlobalKey<NavigatorState>?,
	theme: ThemeData(
	platform: TargetPlatform.android,
	pageTransitionsTheme: const PageTransitionsTheme(
	builders: <TargetPlatform, PageTransitionsBuilder>{
	TargetPlatform.android: FadeThroughPageTransitionsBuilder(),
	},
	),
	),
	onGenerateRoute: (RouteSettings settings) {
	return MaterialPageRoute<void>(
	settings: settings,
	builder: (BuildContext context) {
	return contentBuilder != null
	? contentBuilder!(settings)
	: Center(
	key: ValueKey<String?>(settings.name),
	child: Text(settings.name!),
	);
	},
	);
	},
	);
	}
	}

	class _StatefulTestWidget extends StatefulWidget {
	const _StatefulTestWidget({Key? key, this.name}) : super(key: key);

	final String? name;

	@override
	State<_StatefulTestWidget> createState() => _StatefulTestWidgetState();
	}

	class _StatefulTestWidgetState extends State<_StatefulTestWidget> {
	@override
	Widget build(BuildContext context) {
	return Text(widget.name!);
	}
	}

	typedef _ContentBuilder = Widget Function(RouteSettings settings);