Migrate the tests of flutter_test to null-safety (#67058)

packages/flutter_test/test/accessibility_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -181,7 +179,7 @@ void main() {
   });
 
   group('custom minimum contrast guideline', () {
-    Widget _icon ({IconData icon = Icons.search, Color color, Color background}) {
+    Widget _icon({IconData icon = Icons.search, required Color color, required Color background}) {
       return Container(
         padding: const EdgeInsets.all(8.0),
         color: background,
@@ -189,7 +187,7 @@ void main() {
       );
     }
 
-    Widget _text ({String text = 'Text', Color color, Color background}) {
+    Widget _text({String text = 'Text', required Color color, required Color background}) {
       return Container(
         padding: const EdgeInsets.all(8.0),
         color: background,
@@ -197,7 +195,7 @@ void main() {
       );
     }
 
-    Widget _row (List<Widget> widgets) => _boilerplate(Row(children: widgets));
+    Widget _row(List<Widget> widgets) => _boilerplate(Row(children: widgets));
 
     final Finder _findIcons = find.byWidgetPredicate((Widget widget) => widget is Icon);
     final Finder _findTexts = find.byWidgetPredicate((Widget widget) => widget is Text);
@@ -205,8 +203,8 @@ void main() {
 
     testWidgets('Black icons on white background', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.black, background: Colors.white),
-        _icon (color: Colors.black, background: Colors.white),
+        _icon(color: Colors.black, background: Colors.white),
+        _icon(color: Colors.black, background: Colors.white),
       ]));
 
       await expectLater(tester, meetsGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -214,8 +212,8 @@ void main() {
 
     testWidgets('Black icons on black background', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.black, background: Colors.black),
-        _icon (color: Colors.black, background: Colors.black),
+        _icon(color: Colors.black, background: Colors.black),
+        _icon(color: Colors.black, background: Colors.black),
       ]));
 
       await expectLater(tester, doesNotMeetGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -223,8 +221,8 @@ void main() {
 
     testWidgets('White icons on black background ("dark mode")', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.white, background: Colors.black),
-        _icon (color: Colors.white, background: Colors.black),
+        _icon(color: Colors.white, background: Colors.black),
+        _icon(color: Colors.white, background: Colors.black),
       ]));
 
       await expectLater(tester, meetsGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -232,10 +230,10 @@ void main() {
 
     testWidgets('Using different icons', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.black, background: Colors.white, icon: Icons.more_horiz),
-        _icon (color: Colors.black, background: Colors.white, icon: Icons.description),
-        _icon (color: Colors.black, background: Colors.white, icon: Icons.image),
-        _icon (color: Colors.black, background: Colors.white, icon: Icons.beach_access),
+        _icon(color: Colors.black, background: Colors.white, icon: Icons.more_horiz),
+        _icon(color: Colors.black, background: Colors.white, icon: Icons.description),
+        _icon(color: Colors.black, background: Colors.white, icon: Icons.image),
+        _icon(color: Colors.black, background: Colors.white, icon: Icons.beach_access),
       ]));
 
       await expectLater(tester, meetsGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -243,8 +241,8 @@ void main() {
 
     testWidgets('One invalid instance fails entire test', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.black, background: Colors.white),
-        _icon (color: Colors.black, background: Colors.black),
+        _icon(color: Colors.black, background: Colors.white),
+        _icon(color: Colors.black, background: Colors.black),
       ]));
 
       await expectLater(tester, doesNotMeetGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -252,10 +250,10 @@ void main() {
 
     testWidgets('White on different colors, passing', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.white, background: Colors.red[800], icon: Icons.more_horiz),
-        _icon (color: Colors.white, background: Colors.green[800], icon: Icons.description),
-        _icon (color: Colors.white, background: Colors.blue[800], icon: Icons.image),
-        _icon (color: Colors.white, background: Colors.purple[800], icon: Icons.beach_access),
+        _icon(color: Colors.white, background: Colors.red[800]!, icon: Icons.more_horiz),
+        _icon(color: Colors.white, background: Colors.green[800]!, icon: Icons.description),
+        _icon(color: Colors.white, background: Colors.blue[800]!, icon: Icons.image),
+        _icon(color: Colors.white, background: Colors.purple[800]!, icon: Icons.beach_access),
       ]));
 
       await expectLater(tester, meetsGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -263,10 +261,10 @@ void main() {
 
     testWidgets('White on different colors, failing', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.white, background: Colors.red[200], icon: Icons.more_horiz),
-        _icon (color: Colors.white, background: Colors.green[400], icon: Icons.description),
-        _icon (color: Colors.white, background: Colors.blue[600], icon: Icons.image),
-        _icon (color: Colors.white, background: Colors.purple[800], icon: Icons.beach_access),
+        _icon(color: Colors.white, background: Colors.red[200]!, icon: Icons.more_horiz),
+        _icon(color: Colors.white, background: Colors.green[400]!, icon: Icons.description),
+        _icon(color: Colors.white, background: Colors.blue[600]!, icon: Icons.image),
+        _icon(color: Colors.white, background: Colors.purple[800]!, icon: Icons.beach_access),
       ]));
 
       await expectLater(tester, doesNotMeetGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -280,8 +278,8 @@ void main() {
 
     testWidgets('Absence of icons, passing - 2nd test', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _text (color: Colors.black, background: Colors.white),
-        _text (color: Colors.black, background: Colors.black),
+        _text(color: Colors.black, background: Colors.white),
+        _text(color: Colors.black, background: Colors.black),
       ]));
 
       await expectLater(tester, meetsGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -289,10 +287,10 @@ void main() {
 
     testWidgets('Guideline ignores widgets of other types', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.black, background: Colors.white),
-        _icon (color: Colors.black, background: Colors.white),
-        _text (color: Colors.black, background: Colors.white),
-        _text (color: Colors.black, background: Colors.black),
+        _icon(color: Colors.black, background: Colors.white),
+        _icon(color: Colors.black, background: Colors.white),
+        _text(color: Colors.black, background: Colors.white),
+        _text(color: Colors.black, background: Colors.black),
       ]));
 
       await expectLater(tester, meetsGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -302,8 +300,8 @@ void main() {
 
     testWidgets('Custom minimum ratio - Icons', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.blue, background: Colors.white),
-        _icon (color: Colors.black, background: Colors.white),
+        _icon(color: Colors.blue, background: Colors.white),
+        _icon(color: Colors.black, background: Colors.white),
       ]));
 
       await expectLater(tester, doesNotMeetGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));
@@ -312,8 +310,8 @@ void main() {
 
     testWidgets('Custom minimum ratio - Texts', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _text (color: Colors.blue, background: Colors.white),
-        _text (color: Colors.black, background: Colors.white),
+        _text(color: Colors.blue, background: Colors.white),
+        _text(color: Colors.black, background: Colors.white),
       ]));
 
       await expectLater(tester, doesNotMeetGuideline(CustomMinimumContrastGuideline(finder: _findTexts)));
@@ -322,10 +320,10 @@ void main() {
 
     testWidgets('Custom minimum ratio - Different standards for icons and texts', (WidgetTester tester) async {
       await tester.pumpWidget(_row(<Widget>[
-        _icon (color: Colors.blue, background: Colors.white),
-        _icon (color: Colors.black, background: Colors.white),
-        _text (color: Colors.blue, background: Colors.white),
-        _text (color: Colors.black, background: Colors.white),
+        _icon(color: Colors.blue, background: Colors.white),
+        _icon(color: Colors.black, background: Colors.white),
+        _text(color: Colors.blue, background: Colors.white),
+        _text(color: Colors.black, background: Colors.white),
       ]));
 
       await expectLater(tester, doesNotMeetGuideline(CustomMinimumContrastGuideline(finder: _findIcons)));

packages/flutter_test/test/accessibility_window_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter_test/test/bindings_async_gap_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:flutter/foundation.dart';

packages/flutter_test/test/bindings_environment/flutter_test_variable_is_false_test.dart

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
-import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter_test/test/bindings_environment/flutter_test_variable_is_not_true_or_false_test.dart

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
-import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter_test/test/bindings_environment/flutter_test_variable_is_null_test.dart

-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// @dart = 2.9
-
-import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
-import 'package:flutter_test/flutter_test.dart';
-
-void main() {
-  test('$WidgetsBinding initializes with $AutomatedTestWidgetsFlutterBinding when FLUTTER_TEST is defined but null', () {
-    TestWidgetsFlutterBinding.ensureInitialized(<String, String>{'FLUTTER_TEST': null});
-    expect(WidgetsBinding.instance, isA<AutomatedTestWidgetsFlutterBinding>());
-  });
-}

packages/flutter_test/test/bindings_environment/flutter_test_variable_is_true_test.dart

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
-import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter_test/test/bindings_environment/no_flutter_test_variable_test.dart

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
-import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter_test/test/bindings_test.dart

@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:io';
 
-import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter_test/test/bindings_test_failure.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:io';
 
 import 'package:flutter_test/flutter_test.dart';

packages/flutter_test/test/controller_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:ui';
 
 import 'package:flutter/semantics.dart';

packages/flutter_test/test/custom_exception_reporter/flutter_test_config.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:flutter/foundation.dart';

packages/flutter_test/test/custom_exception_reporter/test_exception_reporter_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'flutter_test_config.dart' as real_test;
 
 void main() => real_test.runTest();

packages/flutter_test/test/demangle_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:flutter/foundation.dart';
@@ -38,7 +36,7 @@ Future<void> main() async {
     await binding.runTest(() async {
       final DebugPrintCallback oldDebugPrint = debugPrint;
       try {
-        debugPrint = (String message, {int wrapWidth}) {};
+        debugPrint = (String? message, {int? wrapWidth}) {};
         debugPrintStack(
           stackTrace: await getMangledStack(),
         );

packages/flutter_test/test/event_simulation_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';

packages/flutter_test/test/finders_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/rendering.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';

packages/flutter_test/test/frame_timing_summarizer_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:ui';
 
 import 'package:flutter_test/flutter_test.dart';

packages/flutter_test/test/goldens_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:io' as io;
 import 'dart:typed_data';
@@ -35,7 +33,7 @@ const List<int> _kSizeFailurePngBytes =
     0, 0, 73, 69, 78, 68, 174, 66, 96, 130];
 
 void main() {
-  MemoryFileSystem fs;
+  late MemoryFileSystem fs;
 
   setUp(() {
     final FileSystemStyle style = io.Platform.isWindows
@@ -86,7 +84,7 @@ void main() {
   });
 
   group('LocalFileComparator', () {
-    LocalFileComparator comparator;
+    late LocalFileComparator comparator;
 
     setUp(() {
       comparator = LocalFileComparator(fs.file(fix('/golden_test.dart')).uri, pathStyle: fs.path.style);

packages/flutter_test/test/integration_bindings_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:io';
 
 import 'package:flutter/widgets.dart';

packages/flutter_test/test/live_binding_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:ui';
 
 import 'package:flutter/material.dart';
@@ -24,7 +22,7 @@ void main() {
   });
 
   testWidgets('Input PointerHoverEvent', (WidgetTester tester) async {
-    PointerHoverEvent hoverEvent;
+    PointerHoverEvent? hoverEvent;
     await tester.pumpWidget(MaterialApp(home: MouseRegion(
       child: const Text('Test'),
       onHover: (PointerHoverEvent event){
@@ -37,7 +35,7 @@ void main() {
     // for mouse input without a down event, moveTo generates a hover event
     await gesture.moveTo(location);
     expect(hoverEvent, isNotNull);
-    expect(hoverEvent.position, location);
+    expect(hoverEvent!.position, location);
     await gesture.removePointer();
   });
 }

packages/flutter_test/test/live_widget_controller_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:ui';
 
 import 'package:flutter/material.dart';
@@ -38,7 +36,7 @@ class AnimateSample extends StatefulWidget {
 
 class _AnimateSampleState extends State<AnimateSample>
     with SingleTickerProviderStateMixin {
-  AnimationController _controller;
+  late AnimationController _controller;
 
   @override
   void initState() {
@@ -68,9 +66,9 @@ void main() {
   test('Test pump on LiveWidgetController', () async {
     runApp(MaterialApp(home: Center(child: CountButton())));
 
-    await SchedulerBinding.instance.endOfFrame;
+    await SchedulerBinding.instance!.endOfFrame;
     final WidgetController controller =
-        LiveWidgetController(WidgetsBinding.instance);
+        LiveWidgetController(WidgetsBinding.instance!);
     await controller.tap(find.text('Counter 0'));
     expect(find.text('Counter 0'), findsOneWidget);
     expect(find.text('Counter 1'), findsNothing);
@@ -81,9 +79,9 @@ void main() {
 
   test('Test pumpAndSettle on LiveWidgetController', () async {
     runApp(MaterialApp(home: Center(child: AnimateSample())));
-    await SchedulerBinding.instance.endOfFrame;
+    await SchedulerBinding.instance!.endOfFrame;
     final WidgetController controller =
-        LiveWidgetController(WidgetsBinding.instance);
+        LiveWidgetController(WidgetsBinding.instance!);
     expect(find.text('Value: 1.0'), findsNothing);
     await controller.pumpAndSettle();
     expect(find.text('Value: 1.0'), findsOneWidget);
@@ -101,9 +99,9 @@ void main() {
         ),
       ),
     );
-    await SchedulerBinding.instance.endOfFrame;
+    await SchedulerBinding.instance!.endOfFrame;
     final WidgetController controller =
-        LiveWidgetController(WidgetsBinding.instance);
+        LiveWidgetController(WidgetsBinding.instance!);
 
     final Offset location = controller.getCenter(find.text('test'));
     final List<PointerEventRecord> records = <PointerEventRecord>[

packages/flutter_test/test/matchers_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:typed_data';
 import 'dart:ui';
 
@@ -13,9 +11,8 @@ import 'package:flutter_test/flutter_test.dart';
 
 /// Class that makes it easy to mock common toStringDeep behavior.
 class _MockToStringDeep {
-  _MockToStringDeep(String str) {
+  _MockToStringDeep(String str) : _lines = <String>[] {
     final List<String> lines = str.split('\n');
-    _lines = <String>[];
     for (int i = 0; i < lines.length - 1; ++i)
       _lines.add('${lines[i]}\n');
 
@@ -31,7 +28,7 @@ class _MockToStringDeep {
   /// Lines in the message to display when [toStringDeep] is called.
   /// For correct toStringDeep behavior, each line should be terminated with a
   /// line break.
-  List<String> _lines;
+  final List<String> _lines;
 
   String toStringDeep({ String prefixLineOne = '', String prefixOtherLines = '' }) {
     final StringBuffer sb = StringBuffer();
@@ -340,7 +337,7 @@ void main() {
   });
 
   group('matchesGoldenFile', () {
-    _FakeComparator comparator;
+    late _FakeComparator comparator;
 
     Widget boilerplate(Widget child) {
       return Directionality(
@@ -561,8 +558,7 @@ void main() {
         currentValueLength: 10,
         maxValueLength: 15,
       );
-      final _FakeSemanticsNode node = _FakeSemanticsNode();
-      node.data = data;
+      final _FakeSemanticsNode node = _FakeSemanticsNode(data);
 
       expect(node, matchesSemantics(
          rect: const Rect.fromLTRB(0.0, 0.0, 10.0, 10.0),
@@ -666,9 +662,9 @@ enum _ComparatorInvocation {
 
 class _FakeComparator implements GoldenFileComparator {
   _ComparatorBehavior behavior = _ComparatorBehavior.returnTrue;
-  _ComparatorInvocation invocation;
-  Uint8List imageBytes;
-  Uri golden;
+  _ComparatorInvocation? invocation;
+  Uint8List? imageBytes;
+  Uri? golden;
 
   @override
   Future<bool> compare(Uint8List imageBytes, Uri golden) {
@@ -683,7 +679,6 @@ class _FakeComparator implements GoldenFileComparator {
       case _ComparatorBehavior.throwTestFailure:
         throw TestFailure('fake message');
     }
-    return Future<bool>.value(false);
   }
 
   @override
@@ -695,12 +690,14 @@ class _FakeComparator implements GoldenFileComparator {
   }
 
   @override
-  Uri getTestUri(Uri key, int version) {
+  Uri getTestUri(Uri key, int? version) {
     return key;
   }
 }
 
 class _FakeSemanticsNode extends SemanticsNode {
+  _FakeSemanticsNode(this.data);
+
   SemanticsData data;
   @override
   SemanticsData getSemanticsData() => data;
@@ -709,7 +706,7 @@ class _FakeSemanticsNode extends SemanticsNode {
 @immutable
 class _CustomColor extends Color {
   const _CustomColor(int value, {this.isEqual}) : super(value);
-  final bool isEqual;
+  final bool? isEqual;
 
   @override
   bool operator ==(Object other) => isEqual ?? super == other;

packages/flutter_test/test/reference_image_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:ui' as ui;
 
 import 'package:flutter_test/flutter_test.dart';

packages/flutter_test/test/restoration_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -75,9 +73,9 @@ void main() {
 }
 
 class _RestorableWidget extends StatefulWidget {
-  const _RestorableWidget({Key key, this.restorationId}) : super(key: key);
+  const _RestorableWidget({Key? key, this.restorationId}) : super(key: key);
 
-  final String restorationId;
+  final String? restorationId;
 
   @override
   State<_RestorableWidget> createState() => _RestorableWidgetState();
@@ -90,7 +88,7 @@ class _RestorableWidgetState extends State<_RestorableWidget> with RestorationMi
   double doubleValue = 1.0; // Not restorable.
 
   @override
-  void restoreState(RestorationBucket oldBucket, bool initialRestore) {
+  void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
     registerForRestoration(stringValue, 'string');
     registerForRestoration(intValue, 'int');
   }
@@ -109,5 +107,5 @@ class _RestorableWidgetState extends State<_RestorableWidget> with RestorationMi
   }
 
   @override
-  String get restorationId => widget.restorationId;
+  String? get restorationId => widget.restorationId;
 }

packages/flutter_test/test/stack_manipulation_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -22,7 +20,7 @@ void main() {
     }
 
     try {
-      throw null;
+      throw Object();
     } catch (e, stack) {
       final List<DiagnosticsNode> information = <DiagnosticsNode>[];
       expect(reportExpectCall(stack, information), 0);

packages/flutter_test/test/test_async_utils_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -18,17 +16,17 @@ import 'package:test_api/test_api.dart' as real_test show expect;
 // of this test is to see how we handle leaking APIs.
 
 class TestAPI {
-  Future<Object> testGuard1() {
-    return TestAsyncUtils.guard<Object>(() async { return null; });
+  Future<Object?> testGuard1() {
+    return TestAsyncUtils.guard<Object?>(() async { return null; });
   }
-  Future<Object> testGuard2() {
-    return TestAsyncUtils.guard<Object>(() async { return null; });
+  Future<Object?> testGuard2() {
+    return TestAsyncUtils.guard<Object?>(() async { return null; });
   }
 }
 
 class TestAPISubclass extends TestAPI {
-  Future<Object> testGuard3() {
-    return TestAsyncUtils.guard<Object>(() async { return null; });
+  Future<Object?> testGuard3() {
+    return TestAsyncUtils.guard<Object?>(() async { return null; });
   }
 }
 
@@ -41,7 +39,7 @@ Future<Object> _guardedThrower() {
 void main() {
   test('TestAsyncUtils - one class', () async {
     final TestAPI testAPI = TestAPI();
-    Future<Object> f1, f2;
+    Future<Object?>? f1, f2;
     f1 = testAPI.testGuard1();
     try {
       f2 = testAPI.testGuard2();
@@ -63,7 +61,7 @@ void main() {
 
   test('TestAsyncUtils - two classes, all callers in superclass', () async {
     final TestAPI testAPI = TestAPISubclass();
-    Future<Object> f1, f2;
+    Future<Object?>? f1, f2;
     f1 = testAPI.testGuard1();
     try {
       f2 = testAPI.testGuard2();
@@ -85,7 +83,7 @@ void main() {
 
   test('TestAsyncUtils - two classes, mixed callers', () async {
     final TestAPISubclass testAPI = TestAPISubclass();
-    Future<Object> f1, f2;
+    Future<Object?>? f1, f2;
     f1 = testAPI.testGuard1();
     try {
       f2 = testAPI.testGuard3();
@@ -107,7 +105,7 @@ void main() {
 
   test('TestAsyncUtils - expect() catches pending async work', () async {
     final TestAPI testAPI = TestAPISubclass();
-    Future<Object> f1;
+    Future<Object?>? f1;
     f1 = testAPI.testGuard1();
     try {
       flutter_test.expect(0, 0);
@@ -128,7 +126,7 @@ void main() {
   });
 
   testWidgets('TestAsyncUtils - expect() catches pending async work', (WidgetTester tester) async {
-    Future<Object> f1, f2;
+    Future<Object?>? f1, f2;
     try {
       f1 = tester.pump();
       f2 = tester.pump();
@@ -170,7 +168,7 @@ void main() {
   });
 
   testWidgets('TestAsyncUtils - expect() catches pending async work', (WidgetTester tester) async {
-    Future<Object> f1;
+    Future<Object?>? f1;
     try {
       f1 = tester.pump();
       TestAsyncUtils.verifyAllScopesClosed();
@@ -195,7 +193,7 @@ void main() {
   });
 
   testWidgets('TestAsyncUtils - expect() catches pending async work', (WidgetTester tester) async {
-    Future<Object> f1;
+    Future<Object?>? f1;
     try {
       f1 = tester.pump();
       TestAsyncUtils.verifyAllScopesClosed();

packages/flutter_test/test/test_config/child_directory/config_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import '../config_test_utils.dart';
 
 void main() {

packages/flutter_test/test/test_config/child_directory/grandchild_directory/config_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import '../../config_test_utils.dart';
 
 void main() {

packages/flutter_test/test/test_config/config_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'config_test_utils.dart';
 
 void main() {

packages/flutter_test/test/test_config/config_test_utils.dart

@@ -2,15 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:flutter_test/flutter_test.dart';
 
 void testConfig(
   String description,
-  String expectedStringValue, {
+  String? expectedStringValue, {
   Map<Type, dynamic> otherExpectedValues = const <Type, dynamic>{int: isNull},
 }) {
   final String actualStringValue = Zone.current[String] as String;

packages/flutter_test/test/test_config/flutter_test_config.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 Future<void> main(FutureOr<void> testMain()) async {

packages/flutter_test/test/test_config/nested_config/config_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import '../config_test_utils.dart';
 
 void main() {

packages/flutter_test/test/test_config/nested_config/flutter_test_config.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 Future<void> main(FutureOr<void> testMain()) async {

packages/flutter_test/test/test_config/project_root/config_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import '../config_test_utils.dart';
 
 void main() {

packages/flutter_test/test/test_text_input_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';

packages/flutter_test/test/widget_tester_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:io';
 import 'dart:ui';
@@ -30,7 +28,7 @@ void main() {
     testWidgets('completes when matcher completes', (WidgetTester tester) async {
       final Completer<void> completer = Completer<void>();
       final Future<void> future = expectLater(null, FakeMatcher(completer));
-      String result;
+      String? result;
       future.then<void>((void value) {
         result = '123';
       });
@@ -62,7 +60,7 @@ void main() {
     });
 
     testWidgets('fails with a descriptive message', (WidgetTester tester) async {
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.text('foo', skipOffstage: false), findsOneWidget);
       } on TestFailure catch (e) {
@@ -85,7 +83,7 @@ void main() {
     testWidgets('fails with a descriptive message', (WidgetTester tester) async {
       await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
 
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.text('foo', skipOffstage: false), findsNothing);
       } on TestFailure catch (e) {
@@ -103,7 +101,7 @@ void main() {
     testWidgets('fails with a descriptive message when skipping', (WidgetTester tester) async {
       await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
 
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.text('foo'), findsNothing);
       } on TestFailure catch (e) {
@@ -156,13 +154,13 @@ void main() {
 
     testWidgets('pumpFrames', (WidgetTester tester) async {
       final List<int> logPaints = <int>[];
-      int initial;
+      int? initial;
 
       final Widget target = _AlwaysAnimating(
         onPaint: () {
-          final int current = SchedulerBinding.instance.currentFrameTimeStamp.inMicroseconds;
+          final int current = SchedulerBinding.instance!.currentFrameTimeStamp.inMicroseconds;
           initial ??= current;
-          logPaints.add(current - initial);
+          logPaints.add(current - initial!);
         },
       );
 
@@ -182,7 +180,7 @@ void main() {
       await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
 
       const String customDescription = 'custom description';
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.byElementPredicate((_) => false, description: customDescription), findsOneWidget);
       } on TestFailure catch (e) {
@@ -199,7 +197,7 @@ void main() {
       await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
 
       const String customDescription = 'custom description';
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.byWidgetPredicate((_) => false, description: customDescription), findsOneWidget);
       } on TestFailure catch (e) {
@@ -250,7 +248,7 @@ void main() {
         ],
       ));
 
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.descendant(
           of: find.widgetWithText(Column, 'foo'),
@@ -312,7 +310,7 @@ void main() {
         ],
       ));
 
-      TestFailure failure;
+      late TestFailure failure;
       try {
         expect(find.ancestor(
           of: find.text('bar'),
@@ -554,7 +552,7 @@ void main() {
 
   group('runAsync', () {
     testWidgets('works with no async calls', (WidgetTester tester) async {
-      String value;
+      String? value;
       await tester.runAsync(() async {
         value = '123';
       });
@@ -574,14 +572,14 @@ void main() {
     });
 
     testWidgets('propagates return values', (WidgetTester tester) async {
-      final String value = await tester.runAsync<String>(() async {
+      final String? value = await tester.runAsync<String>(() async {
         return '123';
       });
       expect(value, '123');
     });
 
     testWidgets('reports errors via framework', (WidgetTester tester) async {
-      final String value = await tester.runAsync<String>(() async {
+      final String? value = await tester.runAsync<String>(() async {
         throw ArgumentError();
       });
       expect(value, isNull);
@@ -630,7 +628,7 @@ void main() {
   });
 
   testWidgets('verifyTickersWereDisposed control test', (WidgetTester tester) async {
-    FlutterError error;
+    late FlutterError error;
     final Ticker ticker = tester.createTicker((Duration duration) {});
     ticker.start();
     try {
@@ -685,7 +683,7 @@ void main() {
 
   group('TargetPlatformVariant', () {
     int numberOfVariationsRun = 0;
-    TargetPlatform origTargetPlatform;
+    TargetPlatform? origTargetPlatform;
 
     setUpAll((){
       origTargetPlatform = debugDefaultTargetPlatformOverride;
@@ -717,7 +715,7 @@ void main() {
   });
 
   group('Pending timer', () {
-    TestExceptionReporter currentExceptionReporter;
+    late TestExceptionReporter currentExceptionReporter;
     setUp(() {
       currentExceptionReporter = reportTestException;
     });
@@ -727,7 +725,7 @@ void main() {
     });
 
     test('Throws assertion message without code', () async {
-      FlutterErrorDetails flutterErrorDetails;
+      late FlutterErrorDetails flutterErrorDetails;
       reportTestException = (FlutterErrorDetails details, String testDescription) {
         flutterErrorDetails = details;
       };
@@ -738,8 +736,8 @@ void main() {
         expect(timer.isActive, true);
       }, () {});
 
-      expect(flutterErrorDetails?.exception, isA<AssertionError>());
-      expect(flutterErrorDetails?.exception?.message, 'A Timer is still pending even after the widget tree was disposed.');
+      expect(flutterErrorDetails.exception, isA<AssertionError>());
+      expect(flutterErrorDetails.exception!.message, 'A Timer is still pending even after the widget tree was disposed.');
     });
   });
 }
@@ -750,8 +748,8 @@ class FakeMatcher extends AsyncMatcher {
   final Completer<void> completer;
 
   @override
-  Future<String> matchAsync(dynamic object) {
-    return completer.future.then<String>((void value) {
+  Future<String?> matchAsync(dynamic object) {
+    return completer.future.then<String?>((void value) {
       return object?.toString();
     });
   }
@@ -761,14 +759,14 @@ class FakeMatcher extends AsyncMatcher {
 }
 
 class _SingleTickerTest extends StatefulWidget {
-  const _SingleTickerTest({Key key}) : super(key: key);
+  const _SingleTickerTest({Key? key}) : super(key: key);
 
   @override
   _SingleTickerTestState createState() => _SingleTickerTestState();
 }
 
 class _SingleTickerTestState extends State<_SingleTickerTest> with SingleTickerProviderStateMixin {
-  AnimationController controller;
+  late AnimationController controller;
 
   @override
   void initState() {
@@ -788,10 +786,10 @@ class _SingleTickerTestState extends State<_SingleTickerTest> with SingleTickerP
 class _AlwaysAnimating extends StatefulWidget {
   const _AlwaysAnimating({
     this.child,
-    this.onPaint,
+    required this.onPaint,
   });
 
-  final Widget child;
+  final Widget? child;
   final VoidCallback onPaint;
 
   @override
@@ -799,7 +797,7 @@ class _AlwaysAnimating extends StatefulWidget {
 }
 
 class _AlwaysAnimatingState extends State<_AlwaysAnimating> with SingleTickerProviderStateMixin {
-  AnimationController _controller;
+  late AnimationController _controller;
 
   @override
   void initState() {
@@ -821,7 +819,7 @@ class _AlwaysAnimatingState extends State<_AlwaysAnimating> with SingleTickerPro
   Widget build(BuildContext context) {
     return AnimatedBuilder(
       animation: _controller.view,
-      builder: (BuildContext context, Widget child) {
+      builder: (BuildContext context, Widget? child) {
         return CustomPaint(
           painter: _AlwaysRepaint(widget.onPaint),
           child: widget.child,

packages/flutter_test/test/window_test.dart

@@ -2,18 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:ui' as ui show window;
 import 'dart:ui' show Size, Locale, WindowPadding, AccessibilityFeatures, Brightness;
 
 import 'package:flutter/widgets.dart' show WidgetsBinding;
 import 'package:flutter_test/flutter_test.dart';
-import 'package:meta/meta.dart';
 
 void main() {
   test('TestWindow can handle new methods without breaking', () {
-    final dynamic testWindow = TestWindow(window: ui.window);
+    final dynamic testWindow = TestWindow(window: ui.window); // ignore: unnecessary_nullable_for_final_variable_declarations
     expect(testWindow.someNewProperty, null);
   });
 
@@ -23,7 +20,7 @@ void main() {
       realValue: ui.window.devicePixelRatio,
       fakeValue: 2.5,
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.devicePixelRatio;
+        return WidgetsBinding.instance!.window.devicePixelRatio;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, double fakeValue) {
         binding.window.devicePixelRatioTestValue = fakeValue;
@@ -37,7 +34,7 @@ void main() {
       realValue: ui.window.physicalSize,
       fakeValue: const Size(50, 50),
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.physicalSize;
+        return WidgetsBinding.instance!.window.physicalSize;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, Size fakeValue) {
         binding.window.physicalSizeTestValue = fakeValue;
@@ -51,7 +48,7 @@ void main() {
       realValue: ui.window.viewInsets,
       fakeValue: const FakeWindowPadding(),
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.viewInsets;
+        return WidgetsBinding.instance!.window.viewInsets;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, WindowPadding fakeValue) {
         binding.window.viewInsetsTestValue = fakeValue;
@@ -65,7 +62,7 @@ void main() {
       realValue: ui.window.padding,
       fakeValue: const FakeWindowPadding(),
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.padding;
+        return WidgetsBinding.instance!.window.padding;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, WindowPadding fakeValue) {
         binding.window.paddingTestValue = fakeValue;
@@ -79,7 +76,7 @@ void main() {
       realValue: ui.window.locale,
       fakeValue: const Locale('fake_language_code'),
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.locale;
+        return WidgetsBinding.instance!.window.locale;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, Locale fakeValue) {
         binding.window.localeTestValue = fakeValue;
@@ -93,7 +90,7 @@ void main() {
       realValue: ui.window.locales,
       fakeValue: <Locale>[const Locale('fake_language_code')],
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.locales;
+        return WidgetsBinding.instance!.window.locales;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, List<Locale> fakeValue) {
         binding.window.localesTestValue = fakeValue;
@@ -107,7 +104,7 @@ void main() {
       realValue: ui.window.textScaleFactor,
       fakeValue: 2.5,
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.textScaleFactor;
+        return WidgetsBinding.instance!.window.textScaleFactor;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, double fakeValue) {
         binding.window.textScaleFactorTestValue = fakeValue;
@@ -121,7 +118,7 @@ void main() {
       realValue: ui.window.alwaysUse24HourFormat,
       fakeValue: !ui.window.alwaysUse24HourFormat,
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.alwaysUse24HourFormat;
+        return WidgetsBinding.instance!.window.alwaysUse24HourFormat;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, bool fakeValue) {
         binding.window.alwaysUse24HourFormatTestValue = fakeValue;
@@ -135,7 +132,7 @@ void main() {
       realValue: ui.window.defaultRouteName,
       fakeValue: 'fake_route',
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.defaultRouteName;
+        return WidgetsBinding.instance!.window.defaultRouteName;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, String fakeValue) {
         binding.window.defaultRouteNameTestValue = fakeValue;
@@ -149,7 +146,7 @@ void main() {
       realValue: ui.window.accessibilityFeatures,
       fakeValue: const FakeAccessibilityFeatures(),
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.accessibilityFeatures;
+        return WidgetsBinding.instance!.window.accessibilityFeatures;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, AccessibilityFeatures fakeValue) {
         binding.window.accessibilityFeaturesTestValue = fakeValue;
@@ -163,7 +160,7 @@ void main() {
       realValue: Brightness.light,
       fakeValue: Brightness.dark,
       propertyRetriever: () {
-        return WidgetsBinding.instance.window.platformBrightness;
+        return WidgetsBinding.instance!.window.platformBrightness;
       },
       propertyFaker: (TestWidgetsFlutterBinding binding, Brightness fakeValue) {
         binding.window.platformBrightnessTestValue = fakeValue;
@@ -184,20 +181,20 @@ void main() {
     testWindow.clearAllTestValues();
 
     // Verify that the window once again reports real property values.
-    expect(WidgetsBinding.instance.window.devicePixelRatio, originalDevicePixelRatio);
-    expect(WidgetsBinding.instance.window.textScaleFactor, originalTextScaleFactor);
+    expect(WidgetsBinding.instance!.window.devicePixelRatio, originalDevicePixelRatio);
+    expect(WidgetsBinding.instance!.window.textScaleFactor, originalTextScaleFactor);
   });
 }
 
 void verifyThatTestWindowCanFakeProperty<WindowPropertyType>({
-  @required WidgetTester tester,
-  @required WindowPropertyType realValue,
-  @required WindowPropertyType fakeValue,
-  @required WindowPropertyType Function() propertyRetriever,
-  @required Function(TestWidgetsFlutterBinding, WindowPropertyType fakeValue) propertyFaker,
+  required WidgetTester tester,
+  required WindowPropertyType? realValue,
+  required WindowPropertyType fakeValue,
+  required WindowPropertyType? Function() propertyRetriever,
+  required Function(TestWidgetsFlutterBinding, WindowPropertyType fakeValue) propertyFaker,
 }) {
-  WindowPropertyType propertyBeforeFaking;
-  WindowPropertyType propertyAfterFaking;
+  WindowPropertyType? propertyBeforeFaking;
+  WindowPropertyType? propertyAfterFaking;
 
   propertyBeforeFaking = propertyRetriever();