Migrate some material tests to nnbd (#67477)

packages/flutter/lib/src/material/popup_menu.dart

@@ -96,8 +96,7 @@ abstract class PopupMenuEntry<T> extends StatefulWidget {
 ///  * [showMenu], a method to dynamically show a popup menu at a given location.
 ///  * [PopupMenuButton], an [IconButton] that automatically shows a menu when
 ///    it is tapped.
-// ignore: prefer_void_to_null, https://github.com/dart-lang/sdk/issues/34416
-class PopupMenuDivider extends PopupMenuEntry<Null> {
+class PopupMenuDivider extends PopupMenuEntry<Never> {
   /// Creates a horizontal divider for a popup menu.
   ///
   /// By default, the divider has a height of 16 logical pixels.

packages/flutter/test/material/navigation_rail_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_test/flutter_test.dart';
@@ -26,8 +24,8 @@ void main() {
       ),
     );
 
-    final TextStyle actualSelectedTextStyle = tester.renderObject<RenderParagraph>(find.text('Abc')).text.style;
-    final TextStyle actualUnselectedTextStyle = tester.renderObject<RenderParagraph>(find.text('Def')).text.style;
+    final TextStyle actualSelectedTextStyle = tester.renderObject<RenderParagraph>(find.text('Abc')).text.style!;
+    final TextStyle actualUnselectedTextStyle = tester.renderObject<RenderParagraph>(find.text('Def')).text.style!;
     expect(actualSelectedTextStyle.fontSize, equals(selectedTextStyle.fontSize));
     expect(actualSelectedTextStyle.fontWeight, equals(selectedTextStyle.fontWeight));
     expect(actualUnselectedTextStyle.fontSize, equals(actualUnselectedTextStyle.fontSize));
@@ -1416,7 +1414,7 @@ void main() {
 
   testWidgets('Extended rail animates the width and labels appear - [textDirection]=LTR', (WidgetTester tester) async {
     bool extended = false;
-    StateSetter stateSetter;
+    late StateSetter stateSetter;
 
     await tester.pumpWidget(
       MaterialApp(
@@ -1553,7 +1551,7 @@ void main() {
 
   testWidgets('Extended rail animates the width and labels appear - [textDirection]=RTL', (WidgetTester tester) async {
     bool extended = false;
-    StateSetter stateSetter;
+    late StateSetter stateSetter;
 
     await tester.pumpWidget(
       MaterialApp(
@@ -1697,7 +1695,7 @@ void main() {
 
   testWidgets('Extended rail gets wider with longer labels are larger text scale', (WidgetTester tester) async {
     bool extended = false;
-    StateSetter stateSetter;
+    late StateSetter stateSetter;
 
     await tester.pumpWidget(
       MaterialApp(
@@ -1708,7 +1706,7 @@ void main() {
               body: Row(
                 children: <Widget>[
                   MediaQuery(
-                    data: MediaQuery.of(context).copyWith(textScaleFactor: 3.0),
+                    data: MediaQuery.of(context)!.copyWith(textScaleFactor: 3.0),
                     child: NavigationRail(
                       selectedIndex: 0,
                       destinations: const <NavigationRailDestination>[
@@ -1755,7 +1753,7 @@ void main() {
 
   testWidgets('Extended rail final width can be changed', (WidgetTester tester) async {
     bool extended = false;
-    StateSetter stateSetter;
+    late StateSetter stateSetter;
 
     await tester.pumpWidget(
       MaterialApp(
@@ -1797,7 +1795,7 @@ void main() {
   /// Regression test for https://github.com/flutter/flutter/issues/65657
   testWidgets('Extended rail transition does not jump from the beginning', (WidgetTester tester) async {
     bool extended = false;
-    StateSetter stateSetter;
+    late StateSetter stateSetter;
 
     await tester.pumpWidget(
       MaterialApp(
@@ -1855,8 +1853,8 @@ void main() {
 
   testWidgets('Extended rail animation can be consumed', (WidgetTester tester) async {
     bool extended = false;
-    Animation<double> animation;
-    StateSetter stateSetter;
+    late Animation<double> animation;
+    late StateSetter stateSetter;
 
     await tester.pumpWidget(
       MaterialApp(
@@ -1899,7 +1897,7 @@ void main() {
   });
 
   testWidgets('onDestinationSelected is called', (WidgetTester tester) async {
-    int selectedIndex;
+    late int selectedIndex;
 
     await _pumpNavigationRail(
       tester,
@@ -2106,14 +2104,14 @@ List<NavigationRailDestination> _destinations() {
 Future<void> _pumpNavigationRail(
   WidgetTester tester, {
   double textScaleFactor = 1.0,
-  NavigationRail navigationRail,
+  required NavigationRail navigationRail,
 }) async {
   await tester.pumpWidget(
     MaterialApp(
       home: Builder(
         builder: (BuildContext context) {
           return MediaQuery(
-            data: MediaQuery.of(context).copyWith(textScaleFactor: textScaleFactor),
+            data: MediaQuery.of(context)!.copyWith(textScaleFactor: textScaleFactor),
             child: Scaffold(
               body: Row(
                 children: <Widget>[
@@ -2131,7 +2129,7 @@ Future<void> _pumpNavigationRail(
   );
 }
 
-Future<void> _pumpLocalizedTestRail(WidgetTester tester, { NavigationRailLabelType labelType, bool extended = false }) async {
+Future<void> _pumpLocalizedTestRail(WidgetTester tester, { NavigationRailLabelType? labelType, bool extended = false }) async {
   await tester.pumpWidget(
     Localizations(
       locale: const Locale('en', 'US'),
@@ -2184,7 +2182,7 @@ TextStyle _iconStyle(WidgetTester tester, IconData icon) {
       of: find.byIcon(icon),
       matching: find.byType(RichText),
     ),
-  ).text.style;
+  ).text.style!;
 }
 
 Finder _opacityAboveLabel(String text) {
@@ -2213,4 +2211,4 @@ Material _railMaterial(WidgetTester tester) {
       matching: find.byType(Material),
     ),
   );
-}
+}
\ No newline at end of file

packages/flutter/test/material/navigation_rail_theme_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/material.dart';
 import 'package:flutter/rendering.dart';
@@ -271,7 +269,7 @@ TextStyle _selectedLabelStyle(WidgetTester tester) {
       of: find.text('Abc'),
       matching: find.byType(RichText),
     ),
-  ).text.style;
+  ).text.style!;
 }
 
 TextStyle _unselectedLabelStyle(WidgetTester tester) {
@@ -280,7 +278,7 @@ TextStyle _unselectedLabelStyle(WidgetTester tester) {
       of: find.text('Def'),
       matching: find.byType(RichText),
     ),
-  ).text.style;
+  ).text.style!;
 }
 
 Align _destinationsAlign(WidgetTester tester) {

packages/flutter/test/material/outlined_button_theme_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_test/flutter_test.dart';
@@ -40,10 +38,10 @@ void main() {
       side: BorderSide(width: 1, color: colorScheme.onSurface.withOpacity(0.12)),
       borderRadius: BorderRadius.circular(4.0),
     ));
-    expect(material.textStyle.color, colorScheme.primary);
-    expect(material.textStyle.fontFamily, 'Roboto');
-    expect(material.textStyle.fontSize, 14);
-    expect(material.textStyle.fontWeight, FontWeight.w500);
+    expect(material.textStyle!.color, colorScheme.primary);
+    expect(material.textStyle!.fontFamily, 'Roboto');
+    expect(material.textStyle!.fontSize, 14);
+    expect(material.textStyle!.fontWeight, FontWeight.w500);
   });
 
   group('[Theme, TextTheme, OutlinedButton style overrides]', () {
@@ -81,7 +79,7 @@ void main() {
       enableFeedback: enableFeedback,
     );
 
-    Widget buildFrame({ ButtonStyle buttonStyle, ButtonStyle themeStyle, ButtonStyle overallStyle }) {
+    Widget buildFrame({ ButtonStyle? buttonStyle, ButtonStyle? themeStyle, ButtonStyle? overallStyle }) {
       final Widget child = Builder(
         builder: (BuildContext context) {
           return OutlinedButton(
@@ -126,15 +124,15 @@ void main() {
     void checkButton(WidgetTester tester) {
       final Material material = tester.widget<Material>(findMaterial);
       final InkWell inkWell = tester.widget<InkWell>(findInkWell);
-      expect(material.textStyle.color, primaryColor);
-      expect(material.textStyle.fontSize, 12);
+      expect(material.textStyle!.color, primaryColor);
+      expect(material.textStyle!.fontSize, 12);
       expect(material.color, backgroundColor);
       expect(material.shadowColor, shadowColor);
       expect(material.elevation, elevation);
-      expect(MaterialStateProperty.resolveAs<MouseCursor>(inkWell.mouseCursor, enabled), enabledMouseCursor);
-      expect(MaterialStateProperty.resolveAs<MouseCursor>(inkWell.mouseCursor, disabled), disabledMouseCursor);
-      expect(inkWell.overlayColor.resolve(hovered), primaryColor.withOpacity(0.04));
-      expect(inkWell.overlayColor.resolve(focused), primaryColor.withOpacity(0.12));
+      expect(MaterialStateProperty.resolveAs<MouseCursor?>(inkWell.mouseCursor, enabled), enabledMouseCursor);
+      expect(MaterialStateProperty.resolveAs<MouseCursor?>(inkWell.mouseCursor, disabled), disabledMouseCursor);
+      expect(inkWell.overlayColor!.resolve(hovered), primaryColor.withOpacity(0.04));
+      expect(inkWell.overlayColor!.resolve(focused), primaryColor.withOpacity(0.12));
       expect(inkWell.enableFeedback, enableFeedback);
       expect(material.borderRadius, null);
       expect(material.shape, shape);
@@ -186,7 +184,7 @@ void main() {
     const Color shadowColor = Color(0xff000001);
     const Color overiddenColor = Color(0xff000002);
 
-    Widget buildFrame({ Color overallShadowColor, Color themeShadowColor, Color shadowColor }) {
+    Widget buildFrame({ Color? overallShadowColor, Color? themeShadowColor, Color? shadowColor }) {
       return MaterialApp(
         theme: ThemeData.from(colorScheme: colorScheme).copyWith(
           shadowColor: overallShadowColor,

packages/flutter/test/material/page_selector_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/material.dart';
 
 const Color kSelectedColor = Color(0xFF00FF00);
 const Color kUnselectedColor = Colors.transparent;
 
-Widget buildFrame(TabController tabController, { Color color, Color selectedColor, double indicatorSize = 12.0 }) {
+Widget buildFrame(TabController tabController, { Color? color, Color? selectedColor, double indicatorSize = 12.0 }) {
   return Directionality(
     textDirection: TextDirection.ltr,
     child: Theme(

packages/flutter/test/material/page_transitions_theme_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/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
@@ -12,7 +10,7 @@ import 'package:flutter_test/flutter_test.dart';
 void main() {
   testWidgets('Default PageTransitionsTheme platform', (WidgetTester tester) async {
     await tester.pumpWidget(const MaterialApp(home: Text('home')));
-    final PageTransitionsTheme theme = Theme.of(tester.element(find.text('home'))).pageTransitionsTheme;
+    final PageTransitionsTheme theme = Theme.of(tester.element(find.text('home')))!.pageTransitionsTheme;
     expect(theme.builders, isNotNull);
     for (final TargetPlatform platform in TargetPlatform.values) {
       if (platform == TargetPlatform.fuchsia) {
@@ -28,7 +26,7 @@ void main() {
       '/': (BuildContext context) => Material(
         child: TextButton(
           child: const Text('push'),
-          onPressed: () { Navigator.of(context).pushNamed('/b'); },
+          onPressed: () { Navigator.of(context)!.pushNamed('/b'); },
         ),
       ),
       '/b': (BuildContext context) => const Text('page b'),
@@ -40,7 +38,7 @@ void main() {
       ),
     );
 
-    expect(Theme.of(tester.element(find.text('push'))).platform, debugDefaultTargetPlatformOverride);
+    expect(Theme.of(tester.element(find.text('push')))!.platform, debugDefaultTargetPlatformOverride);
     expect(find.byType(CupertinoPageTransition), findsOneWidget);
 
     await tester.tap(find.text('push'));
@@ -54,7 +52,7 @@ void main() {
       '/': (BuildContext context) => Material(
         child: TextButton(
           child: const Text('push'),
-          onPressed: () { Navigator.of(context).pushNamed('/b'); },
+          onPressed: () { Navigator.of(context)!.pushNamed('/b'); },
         ),
       ),
       '/b': (BuildContext context) => const Text('page b'),
@@ -73,7 +71,7 @@ void main() {
       );
     }
 
-    expect(Theme.of(tester.element(find.text('push'))).platform, debugDefaultTargetPlatformOverride);
+    expect(Theme.of(tester.element(find.text('push')))!.platform, debugDefaultTargetPlatformOverride);
     expect(findFadeUpwardsPageTransition(), findsOneWidget);
 
     await tester.tap(find.text('push'));
@@ -87,7 +85,7 @@ void main() {
       '/': (BuildContext context) => Material(
         child: TextButton(
           child: const Text('push'),
-          onPressed: () { Navigator.of(context).pushNamed('/b'); },
+          onPressed: () { Navigator.of(context)!.pushNamed('/b'); },
         ),
       ),
       '/b': (BuildContext context) => const Text('page b'),
@@ -113,7 +111,7 @@ void main() {
       );
     }
 
-    expect(Theme.of(tester.element(find.text('push'))).platform, debugDefaultTargetPlatformOverride);
+    expect(Theme.of(tester.element(find.text('push')))!.platform, debugDefaultTargetPlatformOverride);
     expect(findOpenUpwardsPageTransition(), findsOneWidget);
 
     await tester.tap(find.text('push'));
@@ -127,7 +125,7 @@ void main() {
       '/': (BuildContext context) => Material(
         child: TextButton(
           child: const Text('push'),
-          onPressed: () { Navigator.of(context).pushNamed('/b'); },
+          onPressed: () { Navigator.of(context)!.pushNamed('/b'); },
         ),
       ),
       '/b': (BuildContext context) => const Text('page b'),
@@ -153,7 +151,7 @@ void main() {
       );
     }
 
-    expect(Theme.of(tester.element(find.text('push'))).platform, debugDefaultTargetPlatformOverride);
+    expect(Theme.of(tester.element(find.text('push')))!.platform, debugDefaultTargetPlatformOverride);
     expect(findZoomPageTransition(), findsOneWidget);
 
     await tester.tap(find.text('push'));
@@ -171,7 +169,7 @@ void main() {
       '/': (BuildContext context) => Material(
         child: TextButton(
           child: const Text('push'),
-          onPressed: () { Navigator.of(context).pushNamed('/b'); },
+          onPressed: () { Navigator.of(context)!.pushNamed('/b'); },
         ),
       ),
       '/b': (BuildContext context) => StatefulBuilder(

packages/flutter/test/material/paginated_data_table_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/gestures.dart' show DragStartBehavior;
@@ -15,7 +13,7 @@ class TestDataSource extends DataTableSource {
     this.onSelectChanged,
   });
 
-  final void Function(bool) onSelectChanged;
+  final void Function(bool?)? onSelectChanged;
 
   int get generation => _generation;
   int _generation = 0;
@@ -68,7 +66,7 @@ void main() {
         availableRowsPerPage: const <int>[
           2, 4, 8, 16,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) {
+        onRowsPerPageChanged: (int? rowsPerPage) {
           log.add('rows-per-page-changed: $rowsPerPage');
         },
         onPageChanged: (int rowIndex) {
@@ -218,7 +216,7 @@ void main() {
         availableRowsPerPage: const <int>[
           8, 9,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) { },
+        onRowsPerPageChanged: (int? rowsPerPage) { },
         columns: const <DataColumn>[
           DataColumn(label: Text('COL1')),
           DataColumn(label: Text('COL2')),
@@ -243,7 +241,7 @@ void main() {
           source: source,
           rowsPerPage: 501,
           availableRowsPerPage: const <int>[ 501 ],
-          onRowsPerPageChanged: (int rowsPerPage) { },
+          onRowsPerPageChanged: (int? rowsPerPage) { },
           columns: const <DataColumn>[
             DataColumn(label: Text('COL1')),
             DataColumn(label: Text('COL2')),
@@ -280,7 +278,7 @@ void main() {
               rowsPerPage: 5,
               dragStartBehavior: DragStartBehavior.down,
               availableRowsPerPage: const <int>[ 5 ],
-              onRowsPerPageChanged: (int rowsPerPage) { },
+              onRowsPerPageChanged: (int? rowsPerPage) { },
               columns: const <DataColumn>[
                 DataColumn(label: Text('COL1')),
                 DataColumn(label: Text('COL2')),
@@ -315,7 +313,7 @@ void main() {
         availableRowsPerPage: const <int>[
           2, 4, 8, 16,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) {},
+        onRowsPerPageChanged: (int? rowsPerPage) {},
         onPageChanged: (int rowIndex) {},
         columns: const <DataColumn>[
           DataColumn(label: Text('Name')),
@@ -336,7 +334,7 @@ void main() {
         availableRowsPerPage: const <int>[
           2, 4, 8, 16,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) {},
+        onRowsPerPageChanged: (int? rowsPerPage) {},
         onPageChanged: (int rowIndex) {},
         columns: const <DataColumn>[
           DataColumn(label: Text('Name')),
@@ -398,7 +396,7 @@ void main() {
     await binding.setSurfaceSize(const Size(_width, _height));
 
     final TestDataSource source = TestDataSource(
-      onSelectChanged: (bool value) {},
+      onSelectChanged: (bool? value) {},
     );
     Finder cellContent;
     Finder checkbox;
@@ -412,9 +410,9 @@ void main() {
         availableRowsPerPage: const <int>[
           2, 4,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) {},
+        onRowsPerPageChanged: (int? rowsPerPage) {},
         onPageChanged: (int rowIndex) {},
-        onSelectAll: (bool value) {},
+        onSelectAll: (bool? value) {},
         columns: const <DataColumn>[
           DataColumn(label: Text('Name')),
           DataColumn(label: Text('Calories'), numeric: true),
@@ -481,9 +479,9 @@ void main() {
           availableRowsPerPage: const <int>[
             2, 4,
           ],
-          onRowsPerPageChanged: (int rowsPerPage) {},
+          onRowsPerPageChanged: (int? rowsPerPage) {},
           onPageChanged: (int rowIndex) {},
-          onSelectAll: (bool value) {},
+          onSelectAll: (bool? value) {},
           columns: const <DataColumn>[
             DataColumn(label: Text('Name')),
             DataColumn(label: Text('Calories'), numeric: true),
@@ -564,7 +562,7 @@ void main() {
         availableRowsPerPage: const <int>[
           2, 4, 8, 16,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) {},
+        onRowsPerPageChanged: (int? rowsPerPage) {},
         onPageChanged: (int rowIndex) {},
         columns: const <DataColumn>[
           DataColumn(label: Text('Name')),
@@ -620,7 +618,7 @@ void main() {
           availableRowsPerPage: const <int>[
             2, 4, 8, 16,
           ],
-          onRowsPerPageChanged: (int rowsPerPage) {},
+          onRowsPerPageChanged: (int? rowsPerPage) {},
           onPageChanged: (int rowIndex) {},
           columns: const <DataColumn>[
             DataColumn(label: Text('Name')),
@@ -691,7 +689,7 @@ void main() {
         availableRowsPerPage: const <int>[
           2, 4, 8, 16,
         ],
-        onRowsPerPageChanged: (int rowsPerPage) {},
+        onRowsPerPageChanged: (int? rowsPerPage) {},
         onPageChanged: (int rowIndex) {},
         columns: const <DataColumn>[
           DataColumn(label: Text('Name')),
@@ -735,7 +733,7 @@ void main() {
     Widget buildTable(bool checkbox) => MaterialApp(
       home: PaginatedDataTable(
         header: const Text('Test table'),
-        source: TestDataSource(onSelectChanged: (bool value) {}),
+        source: TestDataSource(onSelectChanged: (bool? value) {}),
         showCheckboxColumn: checkbox,
         columns: const <DataColumn>[
           DataColumn(label: Text('Name')),

packages/flutter/test/material/persistent_bottom_sheet_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/material.dart';
 
@@ -25,7 +23,6 @@ void main() {
 
   testWidgets('Verify that a BottomSheet can be rebuilt with ScaffoldFeatureController.setState()', (WidgetTester tester) async {
     final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
-    PersistentBottomSheetController<void> bottomSheet;
     int buildCount = 0;
 
     await tester.pumpWidget(MaterialApp(
@@ -35,7 +32,7 @@ void main() {
       ),
     ));
 
-    bottomSheet = scaffoldKey.currentState.showBottomSheet<void>((_) {
+    final PersistentBottomSheetController<void> bottomSheet = scaffoldKey.currentState!.showBottomSheet<void>((_) {
       return Builder(
         builder: (BuildContext context) {
           buildCount += 1;
@@ -46,7 +43,7 @@ void main() {
 
     await tester.pump();
     expect(buildCount, equals(1));
-    bottomSheet.setState(() { });
+    bottomSheet.setState!(() { });
     await tester.pump();
     expect(buildCount, equals(2));
   });
@@ -92,7 +89,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
       return ListView(
         shrinkWrap: true,
         primary: false,
@@ -124,7 +121,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
       return ListView(
         shrinkWrap: true,
         primary: false,
@@ -159,7 +156,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState.showBottomSheet<void>(
+    scaffoldKey.currentState!.showBottomSheet<void>(
       (BuildContext context) {
         return DraggableScrollableSheet(
           expand: false,
@@ -313,7 +310,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState.showBottomSheet<void>(
+    scaffoldKey.currentState!.showBottomSheet<void>(
       (BuildContext context) {
         return DraggableScrollableSheet(
           expand: false,
@@ -363,7 +360,7 @@ void main() {
 
     int buildCount = 0;
     showBottomSheet<void>(
-      context: key.currentContext,
+      context: key.currentContext!,
       builder: (BuildContext context) {
         return Builder(
           builder: (BuildContext context) {
@@ -378,8 +375,8 @@ void main() {
   });
 
   testWidgets('Scaffold removes top MediaQuery padding', (WidgetTester tester) async {
-    BuildContext scaffoldContext;
-    BuildContext bottomSheetContext;
+    late BuildContext scaffoldContext;
+    late BuildContext bottomSheetContext;
 
     await tester.pumpWidget(MaterialApp(
       home: MediaQuery(
@@ -411,7 +408,7 @@ void main() {
     await tester.pump();
 
     expect(
-      MediaQuery.of(bottomSheetContext).padding,
+      MediaQuery.of(bottomSheetContext)!.padding,
       const EdgeInsets.only(
         bottom: 50.0,
         left: 50.0,
@@ -492,7 +489,7 @@ void main() {
       ),
     ));
 
-    scaffoldKey.currentState.showBottomSheet<void>((BuildContext context) {
+    scaffoldKey.currentState!.showBottomSheet<void>((BuildContext context) {
       return ListView(
         shrinkWrap: true,
         primary: false,
@@ -522,7 +519,7 @@ void main() {
       ),
     ));
 
-    final PersistentBottomSheetController<void> bottomSheet = scaffoldKey.currentState.showBottomSheet<void>((_) {
+    final PersistentBottomSheetController<void> bottomSheet = scaffoldKey.currentState!.showBottomSheet<void>((_) {
       return Builder(
         builder: (BuildContext context) {
           return Container(height: 200.0);

packages/flutter/test/material/popup_menu_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' show window, SemanticsFlag;
 
 import 'package:flutter_test/flutter_test.dart';
@@ -66,7 +64,7 @@ void main() {
 
   testWidgets('PopupMenuButton calls onCanceled callback when an item is not selected', (WidgetTester tester) async {
     int cancels = 0;
-    BuildContext popupContext;
+    late BuildContext popupContext;
     final Key noCallbackKey = UniqueKey();
     final Key withCallbackKey = UniqueKey();
 
@@ -125,7 +123,7 @@ void main() {
     await tester.tap(find.byKey(withCallbackKey));
     await tester.pump();
     await tester.pump(const Duration(seconds: 1));
-    Navigator.of(popupContext).pop();
+    Navigator.of(popupContext)!.pop();
     await tester.pump();
     expect(cancels, equals(2));
   });
@@ -140,7 +138,7 @@ void main() {
       return MaterialApp(
         home: Builder(builder: (BuildContext context) {
           return MediaQuery(
-            data: MediaQuery.of(context).copyWith(
+            data: MediaQuery.of(context)!.copyWith(
               navigationMode: NavigationMode.directional,
             ),
             child: Material(
@@ -191,7 +189,7 @@ void main() {
     await tester.pumpWidget(buildApp(directional: true));
 
     // Try to bring up the popup menu and select the first item from it
-    Focus.of(popupButtonKey.currentContext).requestFocus();
+    Focus.of(popupButtonKey.currentContext!)!.requestFocus();
     await tester.pumpAndSettle();
     await tester.tap(find.byKey(popupButtonKey));
     await tester.pumpAndSettle();
@@ -240,10 +238,10 @@ void main() {
         ),
       ),
     );
-    Focus.of(childKey.currentContext, nullOk: true).requestFocus();
+    Focus.of(childKey.currentContext!)!.requestFocus();
     await tester.pump();
 
-    expect(Focus.of(childKey.currentContext, nullOk: true).hasPrimaryFocus, isFalse);
+    expect(Focus.of(childKey.currentContext!)!.hasPrimaryFocus, isFalse);
     expect(itemBuilderCalled, isFalse);
     expect(onSelectedCalled, isFalse);
   });
@@ -256,7 +254,7 @@ void main() {
       MaterialApp(
         home: Builder(builder: (BuildContext context) {
           return MediaQuery(
-            data: MediaQuery.of(context).copyWith(
+            data: MediaQuery.of(context)!.copyWith(
               navigationMode: NavigationMode.directional,
             ),
             child: Material(
@@ -283,10 +281,10 @@ void main() {
         }),
       ),
     );
-    Focus.of(childKey.currentContext, nullOk: true).requestFocus();
+    Focus.of(childKey.currentContext!)!.requestFocus();
     await tester.pump();
 
-    expect(Focus.of(childKey.currentContext, nullOk: true).hasPrimaryFocus, isTrue);
+    expect(Focus.of(childKey.currentContext!)!.hasPrimaryFocus, isTrue);
   });
 
   testWidgets('PopupMenuItem is only focusable when enabled', (WidgetTester tester) async {
@@ -321,7 +319,7 @@ void main() {
     // Open the popup to build and show the menu contents.
     await tester.tap(find.byKey(popupButtonKey));
     await tester.pumpAndSettle();
-    final FocusNode childNode = Focus.of(childKey.currentContext, nullOk: true);
+    final FocusNode childNode = Focus.of(childKey.currentContext!)!;
     // Now that the contents are shown, request focus on the child text.
     childNode.requestFocus();
     await tester.pumpAndSettle();
@@ -364,7 +362,7 @@ void main() {
     await tester.pumpAndSettle();
 
     expect(itemBuilderCalled, isTrue);
-    expect(Focus.of(childKey.currentContext, nullOk: true).hasPrimaryFocus, isFalse);
+    expect(Focus.of(childKey.currentContext!)!.hasPrimaryFocus, isFalse);
   });
 
   testWidgets('PopupMenuButton is horizontal on iOS', (WidgetTester tester) async {
@@ -637,7 +635,7 @@ void main() {
   });
 
   testWidgets('PopupMenu removes MediaQuery padding', (WidgetTester tester) async {
-    BuildContext popupContext;
+    late BuildContext popupContext;
 
     await tester.pumpWidget(MaterialApp(
       home: MediaQuery(
@@ -674,7 +672,7 @@ void main() {
 
     await tester.pump();
 
-    expect(MediaQuery.of(popupContext).padding, EdgeInsets.zero);
+    expect(MediaQuery.of(popupContext)!.padding, EdgeInsets.zero);
   });
 
   testWidgets('Popup Menu Offset Test', (WidgetTester tester) async {
@@ -1042,7 +1040,7 @@ void main() {
   testWidgets('PopupMenuButton PopupMenuDivider', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/27072
 
-    String selectedValue;
+    late String selectedValue;
     await tester.pumpWidget(
       MaterialApp(
         home: Scaffold(
@@ -1093,41 +1091,6 @@ void main() {
     expect(selectedValue, '2');
   });
 
-  testWidgets('showMenu position required', (WidgetTester tester) async {
-    // Test for https://github.com/flutter/flutter/issues/22256
-    await tester.pumpWidget(
-      MaterialApp(
-        home: Material(
-          child: Center(
-            child: Builder(
-              builder: (BuildContext context) {
-                return ElevatedButton(
-                  onPressed: () {
-                    // Ensure showMenu throws an assertion without a position
-                    expect(() {
-                      // ignore: missing_required_param
-                      showMenu<int>(
-                        context: context,
-                        items: <PopupMenuItem<int>>[
-                          const PopupMenuItem<int>(
-                              value: 1, child: Text('1'),
-                          ),
-                        ],
-                      );
-                    }, throwsAssertionError);
-                  },
-                  child: const Text('Menu Button'),
-                );
-              },
-            ),
-          ),
-        ),
-      ),
-    );
-
-    await tester.tap(find.text('Menu Button'));
-  });
-
   testWidgets('PopupMenuItem child height is a minimum, child is vertically centered', (WidgetTester tester) async {
     final Key popupMenuButtonKey = UniqueKey();
     final Type menuItemType = const PopupMenuItem<String>(child: Text('item')).runtimeType;
@@ -1219,14 +1182,14 @@ void main() {
       double fontSize = 24,
     }) {
       return MaterialApp(
-        builder: (BuildContext context, Widget child) {
+        builder: (BuildContext context, Widget? child) {
           return Directionality(
             textDirection: textDirection,
             child: PopupMenuTheme(
               data: PopupMenuTheme.of(context).copyWith(
-                textStyle: Theme.of(context).textTheme.subtitle1.copyWith(fontSize: fontSize),
+                textStyle: Theme.of(context)!.textTheme.subtitle1!.copyWith(fontSize: fontSize),
               ),
-              child: child,
+              child: child!,
             ),
           );
         },
@@ -1533,7 +1496,7 @@ void main() {
 
     expect(find.text('Tap me please!'), findsNothing);
 
-    globalKey.currentState.showButtonMenu();
+    globalKey.currentState!.showButtonMenu();
     // The PopupMenuItem will appear after an animation, hence,
     // we have to first wait for the tester to settle.
     await tester.pumpAndSettle();
@@ -1571,7 +1534,7 @@ void main() {
 
     await tester.pump();
 
-    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+    expect(RendererBinding.instance!.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
 
     // Test default cursor
     await tester.pumpWidget(
@@ -1594,7 +1557,7 @@ void main() {
       ),
     );
 
-    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+    expect(RendererBinding.instance!.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
 
     // Test default cursor when disabled
     await tester.pumpWidget(
@@ -1618,19 +1581,19 @@ void main() {
       ),
     );
 
-    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
+    expect(RendererBinding.instance!.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
   });
 }
 
 class TestApp extends StatefulWidget {
   const TestApp({
-    Key key,
-    this.textDirection,
+    Key? key,
+    required this.textDirection,
     this.child,
   }) : super(key: key);
 
   final TextDirection textDirection;
-  final Widget child;
+  final Widget? child;
 
   @override
   _TestAppState createState() => _TestAppState();
@@ -1670,7 +1633,7 @@ class MenuObserver extends NavigatorObserver {
   int menuCount = 0;
 
   @override
-  void didPush(Route<dynamic> route, Route<dynamic> previousRoute) {
+  void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) {
     if (route.toString().contains('_PopupMenuRoute')) {
       menuCount++;
     }

packages/flutter/test/material/popup_menu_theme_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_test/flutter_test.dart';
@@ -79,7 +77,7 @@ void main() {
             PopupMenuButton<void>(
               key: popupButtonKey,
               itemBuilder: (BuildContext context) {
-                return <PopupMenuEntry<Object>>[
+                return <PopupMenuEntry<void>>[
                   PopupMenuItem<void>(
                     key: popupItemKey,
                     child: const Text('Example'),
@@ -139,7 +137,7 @@ void main() {
               key: popupButtonKey,
               itemBuilder: (BuildContext context) {
                 return <PopupMenuEntry<Object>>[
-                  PopupMenuItem<void>(
+                  PopupMenuItem<Object>(
                     key: popupItemKey,
                     child: const Text('Example'),
                   ),
@@ -206,7 +204,7 @@ void main() {
               color: color,
               shape: shape,
               itemBuilder: (BuildContext context) {
-                return <PopupMenuEntry<Object>>[
+                return <PopupMenuEntry<void>>[
                   PopupMenuItem<void>(
                     key: popupItemKey,
                     textStyle: textStyle,
@@ -270,7 +268,7 @@ void main() {
               child: PopupMenuButton<void>(
                 key: popupButtonKey,
                 itemBuilder: (BuildContext context) {
-                  return <PopupMenuEntry<Object>>[
+                  return <PopupMenuEntry<void>>[
                     PopupMenuItem<void>(
                       key: popupItemKey,
                       child: const Text('Example'),