Convert some more widget tests to NNBD (#68160)

packages/flutter/test/widgets/slivers_evil_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/physics.dart';
@@ -46,10 +44,10 @@ class TestBehavior extends ScrollBehavior {
 }
 
 class TestScrollPhysics extends ClampingScrollPhysics {
-  const TestScrollPhysics({ ScrollPhysics parent }) : super(parent: parent);
+  const TestScrollPhysics({ ScrollPhysics? parent }) : super(parent: parent);
 
   @override
-  TestScrollPhysics applyTo(ScrollPhysics ancestor) {
+  TestScrollPhysics applyTo(ScrollPhysics? ancestor) {
     return TestScrollPhysics(parent: parent?.applyTo(ancestor) ?? ancestor);
   }
 
@@ -59,9 +57,9 @@ class TestScrollPhysics extends ClampingScrollPhysics {
 
 class TestViewportScrollPosition extends ScrollPositionWithSingleContext {
   TestViewportScrollPosition({
-    ScrollPhysics physics,
-    ScrollContext context,
-    ScrollPosition oldPosition,
+    required ScrollPhysics physics,
+    required ScrollContext context,
+    ScrollPosition? oldPosition,
   }) : super(physics: physics, context: context, oldPosition: oldPosition);
 
   @override

packages/flutter/test/widgets/slivers_keepalive_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/rendering.dart';
@@ -404,8 +402,8 @@ List<Widget> createSwitchedChildList(List<Widget> childList, int i, int j) {
 
 class SwitchingChildBuilderTest extends StatefulWidget {
   const SwitchingChildBuilderTest({
-    this.children,
-    Key key,
+    required this.children,
+    Key? key,
   }) : super(key: key);
 
   final List<Widget> children;
@@ -415,8 +413,8 @@ class SwitchingChildBuilderTest extends StatefulWidget {
 }
 
 class _SwitchingChildBuilderTest extends State<SwitchingChildBuilderTest> {
-  List<Widget> children;
-  Map<Key, int> _mapKeyToIndex;
+  late List<Widget> children;
+  late Map<Key, int> _mapKeyToIndex;
 
   @override
   void initState() {
@@ -424,7 +422,7 @@ class _SwitchingChildBuilderTest extends State<SwitchingChildBuilderTest> {
     children = widget.children;
     _mapKeyToIndex = <Key, int>{};
     for (int index = 0; index < children.length; index += 1) {
-      final Key key = children[index].key;
+      final Key? key = children[index].key;
       if (key != null) {
         _mapKeyToIndex[key] = index;
       }
@@ -438,7 +436,7 @@ class _SwitchingChildBuilderTest extends State<SwitchingChildBuilderTest> {
       children = widget.children;
       _mapKeyToIndex = <Key, int>{};
       for (int index = 0; index < children.length; index += 1) {
-        final Key key = children[index].key;
+        final Key? key = children[index].key;
         if (key != null) {
           _mapKeyToIndex[key] = index;
         }
@@ -475,9 +473,9 @@ class _SwitchingChildBuilderTest extends State<SwitchingChildBuilderTest> {
 
 class SwitchingChildListTest extends StatefulWidget {
   const SwitchingChildListTest({
-    this.children,
+    required this.children,
     this.viewportFraction = 1.0,
-    Key key,
+    Key? key,
   }) : super(key: key);
 
   final List<Widget> children;
@@ -512,9 +510,9 @@ class _SwitchingChildListTest extends State<SwitchingChildListTest> {
 
 class SwitchingSliverListTest extends StatefulWidget {
   const SwitchingSliverListTest({
-    this.children,
+    required this.children,
     this.viewportFraction = 1.0,
-    Key key,
+    Key? key,
   }) : super(key: key);
 
   final List<Widget> children;
@@ -548,9 +546,9 @@ class _SwitchingSliverListTest extends State<SwitchingSliverListTest> {
 
 class WidgetTest0 extends StatefulWidget {
   const WidgetTest0({
-    this.text,
+    required this.text,
     this.keepAlive = false,
-    Key key,
+    Key? key,
   }) : super(key: key);
 
   final String text;
@@ -581,9 +579,9 @@ class _WidgetTest0State extends State<WidgetTest0> with AutomaticKeepAliveClient
 
 class WidgetTest1 extends StatefulWidget {
   const WidgetTest1({
-    this.text,
+    required this.text,
     this.keepAlive = false,
-    Key key,
+    Key? key,
   }) : super(key: key);
 
   final String text;
@@ -614,9 +612,9 @@ class _WidgetTest1State extends State<WidgetTest1> with AutomaticKeepAliveClient
 
 class WidgetTest2 extends StatefulWidget {
   const WidgetTest2({
-    this.text,
+    required this.text,
     this.keepAlive = false,
-    Key key,
+    Key? key,
   }) : super(key: key);
 
   final String text;

packages/flutter/test/widgets/slivers_padding_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 = 2.8
-
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
@@ -544,6 +542,6 @@ void main() {
       ),
       parentUsesSize: true,
     );
-    expect(renderObject.geometry.paintOrigin, 10.0);
+    expect(renderObject.geometry!.paintOrigin, 10.0);
   });
 }

packages/flutter/test/widgets/slivers_protocol_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 = 2.8
-
 import 'dart:math' as math;
 
 import 'package:flutter_test/flutter_test.dart';
@@ -11,9 +9,9 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 
 void verifyPaintPosition(GlobalKey key, Offset ideal) {
-  final RenderObject target = key.currentContext.findRenderObject();
+  final RenderObject target = key.currentContext!.findRenderObject()!;
   expect(target.parent, isA<RenderViewport>());
-  final SliverPhysicalParentData parentData = target.parentData as SliverPhysicalParentData;
+  final SliverPhysicalParentData parentData = target.parentData! as SliverPhysicalParentData;
   final Offset actual = parentData.paintOffset;
   expect(actual, ideal);
 }
@@ -57,7 +55,7 @@ void main() {
 
 class RenderBigSliver extends RenderSliver {
   static const double height = 550.0;
-  double get paintExtent => (height - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent) as double;
+  double get paintExtent => (height - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent);
 
   @override
   void performLayout() {
@@ -70,7 +68,7 @@ class RenderBigSliver extends RenderSliver {
 }
 
 class BigSliver extends LeafRenderObjectWidget {
-  const BigSliver({ Key key }) : super(key: key);
+  const BigSliver({ Key? key }) : super(key: key);
   @override
   RenderBigSliver createRenderObject(BuildContext context) {
     return RenderBigSliver();
@@ -92,7 +90,7 @@ class RenderOverlappingSliver extends RenderSliver {
   }
 
   double get layoutExtent {
-    return (totalHeight - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent) as double;
+    return (totalHeight - constraints.scrollOffset).clamp(0.0, constraints.remainingPaintExtent);
   }
 
   @override
@@ -107,7 +105,7 @@ class RenderOverlappingSliver extends RenderSliver {
 }
 
 class OverlappingSliver extends LeafRenderObjectWidget {
-  const OverlappingSliver({ Key key }) : super(key: key);
+  const OverlappingSliver({ Key? key }) : super(key: key);
   @override
   RenderOverlappingSliver createRenderObject(BuildContext context) {
     return RenderOverlappingSliver();

packages/flutter/test/widgets/slivers_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 = 2.8
-
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
@@ -51,9 +49,7 @@ Future<void> testSliverFixedExtentList(WidgetTester tester, List<String> items)
               childCount : items.length,
               findChildIndexCallback: (Key key) {
                 final ValueKey<String> valueKey = key as ValueKey<String>;
-                final String data = valueKey.value;
-                final int index = items.indexOf(data);
-                return index == -1 ? null : index;
+                return items.indexOf(valueKey.value);
               },
             ),
           ),
@@ -68,7 +64,7 @@ void verify(WidgetTester tester, List<Offset> idealPositions, List<bool> idealVi
     (RenderBox target) => target.localToGlobal(const Offset(0.0, 0.0))
   ).toList();
   final List<bool> actualVisibles = tester.renderObjectList<RenderSliverToBoxAdapter>(find.byType(SliverToBoxAdapter, skipOffstage: false)).map<bool>(
-    (RenderSliverToBoxAdapter target) => target.geometry.visible
+    (RenderSliverToBoxAdapter target) => target.geometry!.visible
   ).toList();
   expect(actualPositions, equals(idealPositions));
   expect(actualVisibles, equals(idealVisibles));
@@ -497,7 +493,7 @@ void main() {
       addRepaintBoundaries: false,
       addSemanticIndexes: false,
     );
-    final KeyedSubtree wrapped = builderThrowsDelegate.build(_NullBuildContext(), 0) as KeyedSubtree;
+    final KeyedSubtree wrapped = builderThrowsDelegate.build(_NullBuildContext(), 0)! as KeyedSubtree;
     expect(wrapped.child, errorText);
     expect(tester.takeException(), 'builder');
     ErrorWidget.builder = oldBuilder;
@@ -614,8 +610,8 @@ void main() {
       expect(semantics.nodesWith(label: 'a'), hasLength(0));
       expect(find.byType(Text), findsNothing);
       final RenderViewport renderViewport = tester.renderObject(find.byType(Viewport));
-      final RenderSliver renderSliver = renderViewport.lastChild;
-      expect(renderSliver.geometry.scrollExtent, 0.0);
+      final RenderSliver renderSliver = renderViewport.lastChild!;
+      expect(renderSliver.geometry!.scrollExtent, 0.0);
       expect(find.byType(SliverOffstage), findsNothing);
     });
 
@@ -633,8 +629,8 @@ void main() {
       expect(semantics.nodesWith(label: 'a'), hasLength(1));
       expect(find.byType(Text), findsOneWidget);
       final RenderViewport renderViewport = tester.renderObject(find.byType(Viewport));
-      final RenderSliver renderSliver = renderViewport.lastChild;
-      expect(renderSliver.geometry.scrollExtent, 14.0);
+      final RenderSliver renderSliver = renderViewport.lastChild!;
+      expect(renderSliver.geometry!.scrollExtent, 14.0);
       expect(find.byType(SliverOffstage), paints..paragraph());
     });
   });
@@ -945,7 +941,7 @@ bool sameHorizontal(Offset a, Offset b) => b.dy == a.dy;
 bool sameVertical(Offset a, Offset b) => b.dx == a.dx;
 
 class TestSliverGrid extends StatelessWidget {
-  const TestSliverGrid(this.children, { Key key }) : super(key: key);
+  const TestSliverGrid(this.children, { Key? key }) : super(key: key);
 
   final List<Widget> children;
 
@@ -1003,7 +999,7 @@ class _TestArbitrarySliverGridLayout implements SliverGridLayout {
 }
 
 class TestSliverFixedExtentList extends StatelessWidget {
-  const TestSliverFixedExtentList(this.children, { Key key }) : super(key: key);
+  const TestSliverFixedExtentList(this.children, { Key? key }) : super(key: key);
 
   final List<Widget> children;
 
@@ -1026,7 +1022,7 @@ class TestSliverFixedExtentList extends StatelessWidget {
 }
 
 class KeepAlive extends StatefulWidget {
-  const KeepAlive(this.data, { Key key }) : super(key: key);
+  const KeepAlive(this.data, { Key? key }) : super(key: key);
 
   final String data;
 

packages/flutter/test/widgets/spacer_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 

packages/flutter/test/widgets/stack_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
@@ -61,7 +59,7 @@ void main() {
     StackParentData parentData;
 
     container = tester.element(find.byKey(key));
-    parentData = container.renderObject.parentData as StackParentData;
+    parentData = container.renderObject!.parentData! as StackParentData;
     expect(parentData.top, isNull);
     expect(parentData.right, isNull);
     expect(parentData.bottom, isNull);
@@ -86,7 +84,7 @@ void main() {
     );
 
     container = tester.element(find.byKey(key));
-    parentData = container.renderObject.parentData as StackParentData;
+    parentData = container.renderObject!.parentData! as StackParentData;
     expect(parentData.top, isNull);
     expect(parentData.right, equals(10.0));
     expect(parentData.bottom, isNull);
@@ -108,7 +106,7 @@ void main() {
     Element containerElement = tester.element(find.byKey(key));
 
     StackParentData parentData;
-    parentData = containerElement.renderObject.parentData as StackParentData;
+    parentData = containerElement.renderObject!.parentData! as StackParentData;
     expect(parentData.top, isNull);
     expect(parentData.right, isNull);
     expect(parentData.bottom, isNull);
@@ -124,7 +122,7 @@ void main() {
     );
     containerElement = tester.element(find.byKey(key));
 
-    parentData = containerElement.renderObject.parentData as StackParentData;
+    parentData = containerElement.renderObject!.parentData! as StackParentData;
     expect(parentData.top, isNull);
     expect(parentData.right, isNull);
     expect(parentData.bottom, isNull);
@@ -153,11 +151,11 @@ void main() {
     );
 
     final Element child0 = tester.element(find.byKey(child0Key));
-    final StackParentData child0RenderObjectParentData = child0.renderObject.parentData as StackParentData;
+    final StackParentData child0RenderObjectParentData = child0.renderObject!.parentData! as StackParentData;
     expect(child0RenderObjectParentData.offset, equals(const Offset(0.0, 0.0)));
 
     final Element child1 = tester.element(find.byKey(child1Key));
-    final StackParentData child1RenderObjectParentData = child1.renderObject.parentData as StackParentData;
+    final StackParentData child1RenderObjectParentData = child1.renderObject!.parentData! as StackParentData;
     expect(child1RenderObjectParentData.offset, equals(const Offset(5.0, 5.0)));
 
     await tester.pumpWidget(
@@ -199,11 +197,11 @@ void main() {
     );
 
     final Element child0 = tester.element(find.byKey(child0Key));
-    final StackParentData child0RenderObjectParentData = child0.renderObject.parentData as StackParentData;
+    final StackParentData child0RenderObjectParentData = child0.renderObject!.parentData! as StackParentData;
     expect(child0RenderObjectParentData.offset, equals(const Offset(0.0, 0.0)));
 
     final Element child1 = tester.element(find.byKey(child1Key));
-    final StackParentData child1RenderObjectParentData = child1.renderObject.parentData as StackParentData;
+    final StackParentData child1RenderObjectParentData = child1.renderObject!.parentData! as StackParentData;
     expect(child1RenderObjectParentData.offset, equals(const Offset(5.0, 5.0)));
 
     await tester.pumpWidget(
@@ -245,7 +243,7 @@ void main() {
 
   testWidgets('Can construct an IndexedStack', (WidgetTester tester) async {
     const int itemCount = 3;
-    List<int> itemsPainted;
+    late List<int> itemsPainted;
 
     Widget buildFrame(int index) {
       itemsPainted = <int>[];
@@ -282,7 +280,7 @@ void main() {
   testWidgets('Can hit test an IndexedStack', (WidgetTester tester) async {
     const Key key = Key('indexedStack');
     const int itemCount = 3;
-    List<int> itemsTapped;
+    late List<int> itemsTapped;
 
     Widget buildFrame(int index) {
       itemsTapped = <int>[];
@@ -336,8 +334,8 @@ void main() {
     StackParentData parentData;
 
     box = tester.element(find.byKey(key));
-    renderBox = box.renderObject as RenderBox;
-    parentData = renderBox.parentData as StackParentData;
+    renderBox = box.renderObject! as RenderBox;
+    parentData = renderBox.parentData! as StackParentData;
     expect(parentData.top, isNull);
     expect(parentData.right, isNull);
     expect(parentData.bottom, isNull);
@@ -364,8 +362,8 @@ void main() {
     );
 
     box = tester.element(find.byKey(key));
-    renderBox = box.renderObject as RenderBox;
-    parentData = renderBox.parentData as StackParentData;
+    renderBox = box.renderObject! as RenderBox;
+    parentData = renderBox.parentData! as StackParentData;
     expect(parentData.top, isNull);
     expect(parentData.right, equals(10.0));
     expect(parentData.bottom, isNull);
@@ -388,7 +386,7 @@ void main() {
   });
 
   testWidgets('IndexedStack with null index', (WidgetTester tester) async {
-    bool tapped;
+    bool? tapped;
 
     await tester.pumpWidget(
       Directionality(

packages/flutter/test/widgets/state_setting_in_scrollables_test.dart

@@ -2,13 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 class Foo extends StatefulWidget {
-  const Foo({ Key key }) : super(key: key);
+  const Foo({ Key? key }) : super(key: key);
   @override
   FooState createState() => FooState();
 }

packages/flutter/test/widgets/stateful_component_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';

packages/flutter/test/widgets/stateful_components_test.dart

@@ -2,13 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 
 class InnerWidget extends StatefulWidget {
-  const InnerWidget({ Key key }) : super(key: key);
+  const InnerWidget({ Key? key }) : super(key: key);
 
   @override
   InnerWidgetState createState() => InnerWidgetState();
@@ -30,7 +28,7 @@ class InnerWidgetState extends State<InnerWidget> {
 }
 
 class OuterContainer extends StatefulWidget {
-  const OuterContainer({ Key key, this.child }) : super(key: key);
+  const OuterContainer({ Key? key, required this.child }) : super(key: key);
 
   final InnerWidget child;
 
@@ -61,7 +59,7 @@ void main() {
     final InnerWidgetState innerElementState = innerElement.state as InnerWidgetState;
     expect(innerElementState.widget, equals(inner1));
     expect(innerElementState._didInitState, isTrue);
-    expect(innerElement.renderObject.attached, isTrue);
+    expect(innerElement.renderObject!.attached, isTrue);
 
     inner2 = const InnerWidget(key: innerKey);
     outer2 = OuterContainer(key: outerKey, child: inner2);
@@ -73,7 +71,7 @@ void main() {
 
     expect(innerElementState.widget, equals(inner2));
     expect(innerElementState._didInitState, isTrue);
-    expect(innerElement.renderObject.attached, isTrue);
+    expect(innerElement.renderObject!.attached, isTrue);
 
     final StatefulElement outerElement = tester.element(find.byKey(outerKey));
     expect(outerElement.state.widget, equals(outer2));
@@ -83,6 +81,6 @@ void main() {
     expect(tester.element(find.byKey(innerKey)), equals(innerElement));
     expect(innerElement.state, equals(innerElementState));
     expect(innerElementState.widget, equals(inner2));
-    expect(innerElement.renderObject.attached, isTrue);
+    expect(innerElement.renderObject!.attached, isTrue);
   });
 }

packages/flutter/test/widgets/status_transitions_test.dart

@@ -2,16 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 
 class TestStatusTransitionWidget extends StatusTransitionWidget {
   const TestStatusTransitionWidget({
-    Key key,
-    this.builder,
-    Animation<double> animation,
+    Key? key,
+    required this.builder,
+    required Animation<double> animation,
   }) : super(key: key, animation: animation);
 
   final WidgetBuilder builder;

packages/flutter/test/widgets/syncing_test.dart

@@ -2,17 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 
 class TestWidget extends StatefulWidget {
   const TestWidget({
-    Key key,
-    this.child,
-    this.persistentState,
-    this.syncedState,
+    Key? key,
+    required this.child,
+    required this.persistentState,
+    required this.syncedState,
   }) : super(key: key);
 
   final Widget child;
@@ -24,8 +22,8 @@ class TestWidget extends StatefulWidget {
 }
 
 class TestWidgetState extends State<TestWidget> {
-  int persistentState;
-  int syncedState;
+  late int persistentState;
+  late int syncedState;
   int updates = 0;
 
   @override
@@ -56,6 +54,7 @@ void main() {
         child: Container(
           child: TestWidget(
             persistentState: 1,
+            syncedState: 0,
             child: Container(),
           ),
         ),
@@ -72,6 +71,7 @@ void main() {
         child: Container(
           child: TestWidget(
             persistentState: 2,
+            syncedState: 0,
             child: Container(),
           ),
         ),
@@ -90,6 +90,7 @@ void main() {
         child: Container(
           child: TestWidget(
             persistentState: 10,
+            syncedState: 0,
             child: Container(),
           ),
         ),
@@ -105,6 +106,7 @@ void main() {
       Container(
         child: TestWidget(
           persistentState: 11,
+          syncedState: 0,
           child: Container(),
         ),
       ),

packages/flutter/test/widgets/table_test.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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/material.dart';
 
 class TestStatefulWidget extends StatefulWidget {
-  const TestStatefulWidget({ Key key }) : super(key: key);
+  const TestStatefulWidget({ Key? key }) : super(key: key);
 
   @override
   TestStatefulWidgetState createState() => TestStatefulWidgetState();
@@ -22,7 +20,7 @@ class TestStatefulWidgetState extends State<TestStatefulWidget> {
 }
 
 class TestChildWidget extends StatefulWidget {
-  const TestChildWidget({ Key key }) : super(key: key);
+  const TestChildWidget({ Key? key }) : super(key: key);
 
   @override
   TestChildState createState() => TestChildState();
@@ -877,7 +875,7 @@ void main() {
       ),
     );
     await tester.pumpWidget(table);
-    final RenderObjectElement element = key0.currentContext as RenderObjectElement;
+    final RenderObjectElement element = key0.currentContext! as RenderObjectElement;
     expect(element, hasAGoodToStringDeep);
     expect(
       element.toStringDeep(minLevel: DiagnosticLevel.info),
@@ -959,7 +957,7 @@ void main() {
   testWidgets(
     'Table widget requires all TableRows to have non-null children',
     (WidgetTester tester) async {
-      FlutterError error;
+      FlutterError? error;
       try {
         await tester.pumpWidget(
           Directionality(
@@ -976,7 +974,7 @@ void main() {
         error = e;
       } finally {
         expect(error, isNotNull);
-        expect(error.toStringDeep(), contains('The children property of TableRow must not be null.'));
+        expect(error!.toStringDeep(), contains('The children property of TableRow must not be null.'));
       }
   });
 

packages/flutter/test/widgets/text_golden_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 = 2.8
-
 @TestOn('!chrome') // Flaky on web
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';

packages/flutter/test/widgets/text_selection_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart' show PointerDeviceKind;
 import 'package:flutter/material.dart';
@@ -18,7 +16,7 @@ class MockClipboard {
 
   final bool getDataThrows;
 
-  Object _clipboardData = <String, dynamic>{
+  dynamic _clipboardData = <String, dynamic>{
     'text': null,
   };
 
@@ -36,16 +34,16 @@ class MockClipboard {
 }
 
 void main() {
-  int tapCount;
-  int singleTapUpCount;
-  int singleTapCancelCount;
-  int singleLongTapStartCount;
-  int doubleTapDownCount;
-  int forcePressStartCount;
-  int forcePressEndCount;
-  int dragStartCount;
-  int dragUpdateCount;
-  int dragEndCount;
+  late int tapCount;
+  late int singleTapUpCount;
+  late int singleTapCancelCount;
+  late int singleLongTapStartCount;
+  late int doubleTapDownCount;
+  late int forcePressStartCount;
+  late int forcePressEndCount;
+  late int dragStartCount;
+  late int dragUpdateCount;
+  late int dragEndCount;
   const Offset forcePressOffset = Offset(400.0, 50.0);
 
   void _handleTapDown(TapDownDetails details) { tapCount++; }
@@ -687,9 +685,9 @@ void main() {
 
 class FakeTextSelectionGestureDetectorBuilderDelegate implements TextSelectionGestureDetectorBuilderDelegate {
   FakeTextSelectionGestureDetectorBuilderDelegate({
-    this.editableTextKey,
-    this.forcePressEnabled,
-    this.selectionEnabled,
+    required this.editableTextKey,
+    required this.forcePressEnabled,
+    required this.selectionEnabled,
   });
 
   @override
@@ -703,7 +701,7 @@ class FakeTextSelectionGestureDetectorBuilderDelegate implements TextSelectionGe
 }
 
 class FakeEditableText extends EditableText {
-  FakeEditableText({Key key}): super(
+  FakeEditableText({Key? key}): super(
     key: key,
     controller: TextEditingController(),
     focusNode: FocusNode(),
@@ -721,7 +719,7 @@ class FakeEditableTextState extends EditableTextState {
   bool showToolbarCalled = false;
 
   @override
-  RenderEditable get renderEditable => _editableKey.currentContext.findRenderObject() as RenderEditable;
+  RenderEditable get renderEditable => _editableKey.currentContext!.findRenderObject()! as RenderEditable;
 
   @override
   bool showToolbar() {
@@ -739,7 +737,7 @@ class FakeEditableTextState extends EditableTextState {
 class FakeEditable extends LeafRenderObjectWidget {
   const FakeEditable(
     this.delegate, {
-    Key key,
+    Key? key,
   }) : super(key: key);
   final EditableTextState delegate;
 
@@ -769,25 +767,25 @@ class FakeRenderEditable extends RenderEditable {
 
   bool selectWordsInRangeCalled = false;
   @override
-  void selectWordsInRange({ @required Offset from, Offset to, @required SelectionChangedCause cause }) {
+  void selectWordsInRange({ required Offset from, Offset? to, required SelectionChangedCause cause }) {
     selectWordsInRangeCalled = true;
   }
 
   bool selectWordEdgeCalled = false;
   @override
-  void selectWordEdge({ @required SelectionChangedCause cause }) {
+  void selectWordEdge({ required SelectionChangedCause cause }) {
     selectWordEdgeCalled = true;
   }
 
   bool selectPositionAtCalled = false;
   @override
-  void selectPositionAt({ @required Offset from, Offset to, @required SelectionChangedCause cause }) {
+  void selectPositionAt({ required Offset from, Offset? to, required SelectionChangedCause cause }) {
     selectPositionAtCalled = true;
   }
 
   bool selectWordCalled = false;
   @override
-  void selectWord({ @required SelectionChangedCause cause }) {
+  void selectWord({ required SelectionChangedCause cause }) {
     selectWordCalled = true;
   }
 }

packages/flutter/test/widgets/text_semantics_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 = 2.8
-
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart';

packages/flutter/test/widgets/text_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 = 2.8
-
 import 'dart:ui' as ui;
 
 import 'package:flutter_test/flutter_test.dart';
@@ -127,7 +125,7 @@ void main() {
 
     final RichText text = tester.firstWidget(find.byType(RichText));
     expect(text, isNotNull);
-    expect(text.text.style.fontSize, 20.0);
+    expect(text.text.style!.fontSize, 20.0);
   });
 
   testWidgets('inline widgets works with ellipsis', (WidgetTester tester) async {
@@ -1007,7 +1005,11 @@ void main() {
   }, semanticsEnabled: true, skip: isBrowser); // Browser semantics have different sizes.
 }
 
-Future<void> _pumpTextWidget({ WidgetTester tester, String text, TextOverflow overflow }) {
+Future<void> _pumpTextWidget({
+  required WidgetTester tester,
+  required String text,
+  required TextOverflow overflow,
+}) {
   return tester.pumpWidget(
     Directionality(
       textDirection: TextDirection.ltr,

packages/flutter/test/widgets/texture_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
@@ -29,7 +27,7 @@ void main() {
     final ContainerLayer containerLayer = ContainerLayer();
     final PaintingContext paintingContext = PaintingContext(containerLayer, Rect.zero);
     textureBox.paint(paintingContext, Offset.zero);
-    final Layer layer = containerLayer.lastChild;
+    final Layer layer = containerLayer.lastChild!;
     expect(layer, isNotNull);
     final TextureLayer textureLayer = layer as TextureLayer;
     expect(textureLayer, isNotNull);
@@ -58,7 +56,7 @@ void main() {
     final ContainerLayer containerLayer = ContainerLayer();
     final PaintingContext paintingContext = PaintingContext(containerLayer, Rect.zero);
     textureBox.paint(paintingContext, Offset.zero);
-    final Layer layer = containerLayer.lastChild;
+    final Layer layer = containerLayer.lastChild!;
     expect(layer, isNotNull);
     final TextureLayer textureLayer = layer as TextureLayer;
     expect(textureLayer, isNotNull);
@@ -86,7 +84,7 @@ void main() {
     final ContainerLayer containerLayer = ContainerLayer();
     final PaintingContext paintingContext = PaintingContext(containerLayer, Rect.zero);
     textureBox.paint(paintingContext, Offset.zero);
-    final Layer layer = containerLayer.lastChild;
+    final Layer layer = containerLayer.lastChild!;
     expect(layer, isNotNull);
     final TextureLayer textureLayer = layer as TextureLayer;
     expect(textureLayer, isNotNull);

packages/flutter/test/widgets/ticker_mode_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 = 2.8
-
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -13,7 +11,7 @@ void main() {
     int outerTickCount = 0;
     int innerTickCount = 0;
 
-    Widget nestedTickerModes({bool innerEnabled, bool outerEnabled}) {
+    Widget nestedTickerModes({required bool innerEnabled, required bool outerEnabled}) {
       return Directionality(
         textDirection: TextDirection.rtl,
         child: TickerMode(
@@ -103,7 +101,7 @@ void main() {
 }
 
 class _TickingWidget extends StatefulWidget {
-  const _TickingWidget({this.onTick});
+  const _TickingWidget({required this.onTick});
 
   final VoidCallback onTick;
 
@@ -112,7 +110,7 @@ class _TickingWidget extends StatefulWidget {
 }
 
 class _TickingWidgetState extends State<_TickingWidget> with SingleTickerProviderStateMixin {
-  Ticker _ticker;
+  late Ticker _ticker;
 
   @override
   void initState() {

packages/flutter/test/widgets/ticker_provider_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 = 2.8
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -104,15 +102,15 @@ void main() {
         child: _SingleTickerTest(key: key),
       );
       await tester.pumpWidget(widget);
-      FlutterError error;
-      key.currentState.controller.repeat();
+      FlutterError? error;
+      key.currentState!.controller.repeat();
       try {
-        key.currentState.dispose();
+        key.currentState!.dispose();
       } on FlutterError catch (e) {
         error = e;
       } finally {
         expect(error, isNotNull);
-        expect(error.diagnostics.length, 4);
+        expect(error!.diagnostics.length, 4);
         expect(error.diagnostics[2].level, DiagnosticLevel.hint);
         expect(
           error.diagnostics[2].toStringDeep(),
@@ -137,7 +135,7 @@ void main() {
             '     created))\n'
             '     The stack trace when the Ticker was actually created was:'
         ));
-        key.currentState.controller.stop();
+        key.currentState!.controller.stop();
       }
     });
 
@@ -147,15 +145,15 @@ void main() {
         child: _SingleTickerTest(key: key),
       );
       await tester.pumpWidget(widget);
-      FlutterError error;
-      key.currentState.controller.repeat();
+      FlutterError? error;
+      key.currentState!.controller.repeat();
       try {
-        key.currentState.dispose();
+        key.currentState!.dispose();
       } on FlutterError catch (e) {
         error = e;
       } finally {
         expect(error, isNotNull);
-        expect(error.diagnostics.length, 4);
+        expect(error!.diagnostics.length, 4);
         expect(error.diagnostics[2].level, DiagnosticLevel.hint);
         expect(
           error.diagnostics[2].toStringDeep(),
@@ -180,7 +178,7 @@ void main() {
           '     created))\n'
           '     The stack trace when the Ticker was actually created was:'
         ));
-        key.currentState.controller.stop();
+        key.currentState!.controller.stop();
       }
     });
 
@@ -190,15 +188,15 @@ void main() {
         child: _MultipleTickerTest(key: key),
       );
       await tester.pumpWidget(widget);
-      FlutterError error;
-      key.currentState.controllers.first.repeat();
+      FlutterError? error;
+      key.currentState!.controllers.first.repeat();
       try {
-        key.currentState.dispose();
+        key.currentState!.dispose();
       } on FlutterError catch (e) {
         error = e;
       } finally {
         expect(error, isNotNull);
-        expect(error.diagnostics.length, 4);
+        expect(error!.diagnostics.length, 4);
         expect(error.diagnostics[2].level, DiagnosticLevel.hint);
         expect(
           error.diagnostics[2].toStringDeep(),
@@ -223,14 +221,14 @@ void main() {
           '     _MultipleTickerTestState#00000(lifecycle state: created,\n'
           '     tickers: tracking 0 tickers))'
         ));
-        key.currentState.controllers.first.stop();
+        key.currentState!.controllers.first.stop();
       }
     });
   });
 }
 
 class BoringTickerTest extends StatefulWidget {
-  const BoringTickerTest({ Key key }) : super(key: key);
+  const BoringTickerTest({ Key? key }) : super(key: key);
   @override
   _BoringTickerTestState createState() => _BoringTickerTestState();
 }
@@ -241,14 +239,14 @@ class _BoringTickerTestState extends State<BoringTickerTest> with SingleTickerPr
 }
 
 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() {
@@ -266,7 +264,7 @@ class _SingleTickerTestState extends State<_SingleTickerTest> with SingleTickerP
 }
 
 class _MultipleTickerTest extends StatefulWidget {
-  const _MultipleTickerTest({Key key}) : super(key: key);
+  const _MultipleTickerTest({Key? key}) : super(key: key);
 
   @override
   _MultipleTickerTestState createState() => _MultipleTickerTestState();

packages/flutter/test/widgets/title_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 = 2.8
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/services.dart';
@@ -28,18 +26,6 @@ void main() {
     expect(widget.color, equals(const Color(0xFF00FF00)));
   });
 
-  testWidgets('should not allow null title or color', (WidgetTester tester) async {
-    expect(() => Title(
-      title: null,
-      color: const Color(0xFF00FF00),
-      child: Container(),
-    ), throwsAssertionError);
-    expect(() => Title(
-      color: null,
-      child: Container(),
-    ), throwsAssertionError);
-  });
-
   testWidgets('should not allow non-opaque color', (WidgetTester tester) async {
     expect(() => Title(
       color: const Color(0x00000000),

packages/flutter/test/widgets/tracking_scroll_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 = 2.8
-
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 

packages/flutter/test/widgets/transform_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 = 2.8
-
 import 'dart:math' as math;
 import 'dart:ui' as ui;
 
@@ -255,7 +253,7 @@ void main() {
     expect(layers.length, 2);
     // The first transform is from the render view.
     final TransformLayer layer = layers[1] as TransformLayer;
-    final Matrix4 transform = layer.transform;
+    final Matrix4 transform = layer.transform!;
     expect(transform.getTranslation(), equals(Vector3(100.0, 75.0, 0.0)));
   });
 
@@ -272,7 +270,7 @@ void main() {
     expect(layers.length, 2);
     // The first transform is from the render view.
     final TransformLayer layer = layers[1] as TransformLayer;
-    final Matrix4 transform = layer.transform;
+    final Matrix4 transform = layer.transform!;
     expect(transform.storage, <dynamic>[
       moreOrLessEquals(0.0), 1.0, 0.0, 0.0,
       -1.0, moreOrLessEquals(0.0), 0.0, 0.0,
@@ -327,7 +325,7 @@ void main() {
     expect(layers.length, 2);
     // The first transform is from the render view.
     final TransformLayer layer = layers[1] as TransformLayer;
-    final Matrix4 transform = layer.transform;
+    final Matrix4 transform = layer.transform!;
     expect(transform.storage, <dynamic>[
       // These are column-major, not row-major.
       2.0, 0.0, 0.0, 0.0,
@@ -380,8 +378,8 @@ void main() {
     (WidgetTester tester) async {
       for (double angle = 0; angle <= math.pi/4; angle += 0.01) {
         await tester.pumpWidget(RepaintBoundary(child: _generateTransform(true, angle)));
-        final RenderBox renderBox = tester.binding.renderView.child;
-        final OffsetLayer layer = renderBox.debugLayer as OffsetLayer;
+        final RenderBox renderBox = tester.binding.renderView.child!;
+        final OffsetLayer layer = renderBox.debugLayer! as OffsetLayer;
         final ui.Image imageWithCompositing = await layer.toImage(renderBox.paintBounds);
 
         await tester.pumpWidget(RepaintBoundary(child: _generateTransform(false, angle)));

packages/flutter/test/widgets/transformed_scrollable_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 = 2.8
-
 import 'dart:math' as math;
 
 import 'package:flutter/material.dart';