enable use_key_in_widget_constructors lint (#77032)

analysis_options.yaml

@@ -168,8 +168,8 @@ linter:
     - prefer_if_null_operators
     - prefer_initializing_formals
     - prefer_inlined_adds
-    # - prefer_int_literals # not yet tested
-    # - prefer_interpolation_to_compose_strings # not yet tested
+    # - prefer_int_literals # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#use-double-literals-for-double-constants
+    # - prefer_interpolation_to_compose_strings # doesn't work with raw strings, see https://github.com/dart-lang/linter/issues/2490
     - prefer_is_empty
     - prefer_is_not_empty
     - prefer_is_not_operator
@@ -220,7 +220,7 @@ linter:
     # - use_function_type_syntax_for_parameters # not yet tested
     # - use_if_null_to_convert_nulls_to_bools # not yet tested
     - use_is_even_rather_than_modulo
-    # - use_key_in_widget_constructors # not yet tested
+    - use_key_in_widget_constructors
     - use_late_for_private_fields_and_variables
     # - use_named_constants # not yet yested
     - use_raw_strings

dev/benchmarks/complex_layout/lib/main.dart

@@ -7,13 +7,15 @@ import 'package:flutter/scheduler.dart' show timeDilation;
 
 void main() {
   runApp(
-    ComplexLayoutApp()
+    const ComplexLayoutApp()
   );
 }
 
 enum ScrollMode { complex, tile }
 
 class ComplexLayoutApp extends StatefulWidget {
+  const ComplexLayoutApp({Key key}) : super(key: key);
+
   @override
   ComplexLayoutAppState createState() => ComplexLayoutAppState();
 
@@ -68,7 +70,7 @@ class TileScrollLayout extends StatelessWidget {
             child: Material(
               elevation: (index % 5 + 1).toDouble(),
               color: Colors.white,
-              child: IconBar(),
+              child: const IconBar(),
             ),
           );
         },
@@ -101,7 +103,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
               print('Pressed search');
             },
           ),
-          TopBarMenu(),
+          const TopBarMenu(),
         ],
       ),
       body: Column(
@@ -118,7 +120,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
               },
             ),
           ),
-          BottomBar(),
+          const BottomBar(),
         ],
       ),
       drawer: const GalleryDrawer(),
@@ -127,6 +129,8 @@ class ComplexLayoutState extends State<ComplexLayout> {
 }
 
 class TopBarMenu extends StatelessWidget {
+  const TopBarMenu({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return PopupMenuButton<String>(
@@ -178,7 +182,7 @@ class TopBarMenu extends StatelessWidget {
 }
 
 class MenuItemWithIcon extends StatelessWidget {
-  const MenuItemWithIcon(this.icon, this.title, this.subtitle);
+  const MenuItemWithIcon(this.icon, this.title, this.subtitle, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -209,15 +213,15 @@ class FancyImageItem extends StatelessWidget {
     return ListBody(
       children: <Widget>[
         UserHeader('Ali Connors $index'),
-        ItemDescription(),
-        ItemImageBox(),
-        InfoBar(),
+        const ItemDescription(),
+        const ItemImageBox(),
+        const InfoBar(),
         const Padding(
           padding: EdgeInsets.symmetric(horizontal: 8.0),
           child: Divider(),
         ),
-        IconBar(),
-        FatDivider(),
+        const IconBar(),
+        const FatDivider(),
       ],
     );
   }
@@ -233,19 +237,21 @@ class FancyGalleryItem extends StatelessWidget {
       children: <Widget>[
         const UserHeader('Ali Connors'),
         ItemGalleryBox(index),
-        InfoBar(),
+        const InfoBar(),
         const Padding(
           padding: EdgeInsets.symmetric(horizontal: 8.0),
           child: Divider(),
         ),
-        IconBar(),
-        FatDivider(),
+        const IconBar(),
+        const FatDivider(),
       ],
     );
   }
 }
 
 class InfoBar extends StatelessWidget {
+  const InfoBar({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -262,6 +268,8 @@ class InfoBar extends StatelessWidget {
 }
 
 class IconBar extends StatelessWidget {
+  const IconBar({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -279,7 +287,7 @@ class IconBar extends StatelessWidget {
 }
 
 class IconWithText extends StatelessWidget {
-  const IconWithText(this.icon, this.title);
+  const IconWithText(this.icon, this.title, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -300,7 +308,7 @@ class IconWithText extends StatelessWidget {
 }
 
 class MiniIconWithText extends StatelessWidget {
-  const MiniIconWithText(this.icon, this.title);
+  const MiniIconWithText(this.icon, this.title, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -329,6 +337,8 @@ class MiniIconWithText extends StatelessWidget {
 }
 
 class FatDivider extends StatelessWidget {
+  const FatDivider({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -339,7 +349,7 @@ class FatDivider extends StatelessWidget {
 }
 
 class UserHeader extends StatelessWidget {
-  const UserHeader(this.userName);
+  const UserHeader(this.userName, {Key key}) : super(key: key);
 
   final String userName;
 
@@ -380,7 +390,7 @@ class UserHeader extends StatelessWidget {
               ],
             ),
           ),
-          TopBarMenu(),
+          const TopBarMenu(),
         ],
       ),
     );
@@ -388,6 +398,8 @@ class UserHeader extends StatelessWidget {
 }
 
 class ItemDescription extends StatelessWidget {
+  const ItemDescription({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const Padding(
@@ -398,6 +410,8 @@ class ItemDescription extends StatelessWidget {
 }
 
 class ItemImageBox extends StatelessWidget {
+  const ItemImageBox({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -477,7 +491,7 @@ class ItemImageBox extends StatelessWidget {
 }
 
 class ItemGalleryBox extends StatelessWidget {
-  const ItemGalleryBox(this.index);
+  const ItemGalleryBox(this.index, {Key key}) : super(key: key);
 
   final int index;
 
@@ -548,6 +562,8 @@ class ItemGalleryBox extends StatelessWidget {
 }
 
 class BottomBar extends StatelessWidget {
+  const BottomBar({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -574,7 +590,7 @@ class BottomBar extends StatelessWidget {
 }
 
 class BottomBarButton extends StatelessWidget {
-  const BottomBarButton(this.icon, this.title);
+  const BottomBarButton(this.icon, this.title, {Key key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -618,7 +634,7 @@ class GalleryDrawer extends StatelessWidget {
         key: const PageStorageKey<String>('gallery-drawer'),
         padding: EdgeInsets.zero,
         children: <Widget>[
-          FancyDrawerHeader(),
+          const FancyDrawerHeader(),
           ListTile(
             key: const Key('scroll-switcher'),
             title: const Text('Scroll Mode'),
@@ -668,6 +684,8 @@ class GalleryDrawer extends StatelessWidget {
 }
 
 class FancyDrawerHeader extends StatelessWidget {
+  const FancyDrawerHeader({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(

dev/benchmarks/complex_layout/test_memory/scroll_perf.dart

@@ -27,7 +27,7 @@ Future<void> main() async {
       ready.complete();
     },
     behavior: HitTestBehavior.opaque,
-    child: IgnorePointer(
+    child: const IgnorePointer(
       ignoring: true,
       child: ComplexLayoutApp(),
     ),
@@ -45,7 +45,7 @@ Future<void> main() async {
 
   // remove onTap handler, enable pointer events for app
   runApp(GestureDetector(
-    child: IgnorePointer(
+    child: const IgnorePointer(
       ignoring: false,
       child: ComplexLayoutApp(),
     ),

dev/benchmarks/macrobenchmarks/lib/main.dart

@@ -29,7 +29,7 @@ const String kMacrobenchmarks = 'Macrobenchmarks';
 void main() => runApp(const MacrobenchmarksApp());
 
 class MacrobenchmarksApp extends StatelessWidget {
-  const MacrobenchmarksApp({this.initialRoute = '/'});
+  const MacrobenchmarksApp({Key key, this.initialRoute = '/'}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -37,25 +37,25 @@ class MacrobenchmarksApp extends StatelessWidget {
       title: kMacrobenchmarks,
       initialRoute: initialRoute,
       routes: <String, WidgetBuilder>{
-        '/': (BuildContext context) => HomePage(),
-        kCullOpacityRouteName: (BuildContext context) => CullOpacityPage(),
-        kCubicBezierRouteName: (BuildContext context) => CubicBezierPage(),
-        kBackdropFilterRouteName: (BuildContext context) => BackdropFilterPage(),
-        kPostBackdropFilterRouteName: (BuildContext context) => PostBackdropFilterPage(),
-        kSimpleAnimationRouteName: (BuildContext context) => SimpleAnimationPage(),
-        kPictureCacheRouteName: (BuildContext context) => PictureCachePage(),
-        kLargeImageChangerRouteName: (BuildContext context) => LargeImageChangerPage(),
-        kLargeImagesRouteName: (BuildContext context) => LargeImagesPage(),
-        kTextRouteName: (BuildContext context) => TextPage(),
-        kFullscreenTextRouteName: (BuildContext context) => TextFieldPage(),
-        kAnimatedPlaceholderRouteName: (BuildContext context) => AnimatedPlaceholderPage(),
-        kColorFilterAndFadeRouteName: (BuildContext context) => ColorFilterAndFadePage(),
+        '/': (BuildContext context) => const HomePage(),
+        kCullOpacityRouteName: (BuildContext context) => const CullOpacityPage(),
+        kCubicBezierRouteName: (BuildContext context) => const CubicBezierPage(),
+        kBackdropFilterRouteName: (BuildContext context) => const BackdropFilterPage(),
+        kPostBackdropFilterRouteName: (BuildContext context) => const PostBackdropFilterPage(),
+        kSimpleAnimationRouteName: (BuildContext context) => const SimpleAnimationPage(),
+        kPictureCacheRouteName: (BuildContext context) => const PictureCachePage(),
+        kLargeImageChangerRouteName: (BuildContext context) => const LargeImageChangerPage(),
+        kLargeImagesRouteName: (BuildContext context) => const LargeImagesPage(),
+        kTextRouteName: (BuildContext context) => const TextPage(),
+        kFullscreenTextRouteName: (BuildContext context) => const TextFieldPage(),
+        kAnimatedPlaceholderRouteName: (BuildContext context) => const AnimatedPlaceholderPage(),
+        kColorFilterAndFadeRouteName: (BuildContext context) => const ColorFilterAndFadePage(),
         kFadingChildAnimationRouteName: (BuildContext context) => const FilteredChildAnimationPage(FilterType.opacity),
         kImageFilteredTransformAnimationRouteName: (BuildContext context) => const FilteredChildAnimationPage(FilterType.rotateFilter),
         kMultiWidgetConstructionRouteName: (BuildContext context) => const MultiWidgetConstructTable(10, 20),
-        kHeavyGridViewRouteName: (BuildContext context) => HeavyGridViewPage(),
-        kSimpleScrollRouteName: (BuildContext context) => SimpleScroll(),
-        kStackSizeRouteName: (BuildContext context) => StackSizePage(),
+        kHeavyGridViewRouteName: (BuildContext context) => const HeavyGridViewPage(),
+        kSimpleScrollRouteName: (BuildContext context) => const SimpleScroll(),
+        kStackSizeRouteName: (BuildContext context) => const StackSizePage(),
       },
     );
   }
@@ -64,6 +64,8 @@ class MacrobenchmarksApp extends StatelessWidget {
 }
 
 class HomePage extends StatelessWidget {
+  const HomePage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/benchmarks/macrobenchmarks/lib/src/animated_placeholder.dart

@@ -24,6 +24,8 @@ const String kBlueSquare = 'iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAYAAAAeP4ixAAAASEl'
 /// A 10x10 grid of animated looping placeholder gifts that fade into a
 /// blue square.
 class AnimatedPlaceholderPage extends StatelessWidget {
+  const AnimatedPlaceholderPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return GridView.builder(

dev/benchmarks/macrobenchmarks/lib/src/backdrop_filter.dart

@@ -7,6 +7,8 @@ import 'dart:ui';
 import 'package:flutter/material.dart';
 
 class BackdropFilterPage extends StatefulWidget {
+  const BackdropFilterPage({Key key}) : super(key: key);
+
   @override
   _BackdropFilterPageState createState() => _BackdropFilterPageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/color_filter_and_fade.dart

@@ -9,6 +9,8 @@ import 'package:flutter/material.dart';
 // This tests whether the Opacity layer raster cache works with color filters.
 // See https://github.com/flutter/flutter/issues/51975.
 class ColorFilterAndFadePage extends StatefulWidget {
+  const ColorFilterAndFadePage({Key key}) : super(key: key);
+
   @override
   _ColorFilterAndFadePageState createState() => _ColorFilterAndFadePageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/cubic_bezier.dart

@@ -8,6 +8,8 @@ import 'package:flutter/material.dart';
 
 // Based on https://github.com/eseidelGoogle/bezier_perf/blob/master/lib/main.dart
 class CubicBezierPage extends StatelessWidget {
+  const CubicBezierPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Center(
@@ -22,7 +24,7 @@ class CubicBezierPage extends StatelessWidget {
 }
 
 class Bezier extends StatelessWidget {
-  const Bezier(this.color, this.scale, {this.blur = 0.0, this.delay = 0.0});
+  const Bezier(this.color, this.scale, {Key key, this.blur = 0.0, this.delay = 0.0}) : super(key: key);
 
   final Color color;
   final double scale;
@@ -91,7 +93,7 @@ class PathDetail {
 }
 
 class AnimatedBezier extends StatefulWidget {
-  const AnimatedBezier(this.color, this.scale, {this.blur = 0.0, this.delay});
+  const AnimatedBezier(this.color, this.scale, {Key key, this.blur = 0.0, this.delay}) : super(key: key);
 
   final Color color;
   final double scale;

dev/benchmarks/macrobenchmarks/lib/src/cull_opacity.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class CullOpacityPage extends StatefulWidget {
+  const CullOpacityPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _CullOpacityPageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/filtered_child_animation.dart

@@ -12,10 +12,11 @@ enum FilterType {
 }
 
 class FilteredChildAnimationPage extends StatefulWidget {
-  const FilteredChildAnimationPage(this.initialFilterType, [
+  const FilteredChildAnimationPage(this.initialFilterType, {
+    Key key,
     this.initialComplexChild = true,
     this.initialUseRepaintBoundary = true,
-  ]);
+  }) : super(key: key);
 
   final FilterType initialFilterType;
   final bool initialComplexChild;

dev/benchmarks/macrobenchmarks/lib/src/fullscreenTextField.dart

@@ -48,6 +48,8 @@ const String textLotsOfText = 'Lorem ipsum dolor sit amet, consectetur '
   '🦻 👃 🫀 🫁 🧠 🦷 🦴 👀 👁 👅 👄 💋 🩸';
 
 class TextFieldPage extends StatelessWidget {
+  const TextFieldPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(

dev/benchmarks/macrobenchmarks/lib/src/heavy_grid_view.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class HeavyGridViewPage extends StatelessWidget {
+  const HeavyGridViewPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return GridView.builder(

dev/benchmarks/macrobenchmarks/lib/src/large_image_changer.dart

@@ -8,6 +8,8 @@ import 'package:flutter/material.dart';
 
 /// Displays a new (from image cache's perspective) large image every 500ms.
 class LargeImageChangerPage extends StatefulWidget {
+  const LargeImageChangerPage({Key key}) : super(key: key);
+
   @override
   _LargeImageChangerState createState() => _LargeImageChangerState();
 }

dev/benchmarks/macrobenchmarks/lib/src/large_images.dart

@@ -7,6 +7,8 @@ import 'dart:typed_data';
 import 'package:flutter/material.dart';
 
 class LargeImagesPage extends StatelessWidget {
+  const LargeImagesPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final ImageCache imageCache = PaintingBinding.instance.imageCache;

dev/benchmarks/macrobenchmarks/lib/src/picture_cache.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class PictureCachePage extends StatelessWidget {
+  const PictureCachePage({Key key}) : super(key: key);
+
   static const List<String> kTabNames = <String>['1', '2', '3', '4', '5'];
 
   @override

dev/benchmarks/macrobenchmarks/lib/src/post_backdrop_filter.dart

@@ -7,6 +7,8 @@ import 'dart:ui';
 import 'package:flutter/material.dart';
 
 class PostBackdropFilterPage extends StatefulWidget {
+  const PostBackdropFilterPage({Key key}) : super(key: key);
+
   @override
   _PostBackdropFilterPageState createState() => _PostBackdropFilterPageState();
 }

dev/benchmarks/macrobenchmarks/lib/src/simple_animation.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class SimpleAnimationPage extends StatelessWidget {
+  const SimpleAnimationPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const Center(child: LinearProgressIndicator());

dev/benchmarks/macrobenchmarks/lib/src/simple_scroll.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class SimpleScroll extends StatelessWidget {
+  const SimpleScroll({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return ListView(

dev/benchmarks/macrobenchmarks/lib/src/stack_size.dart

@@ -81,6 +81,8 @@ final GetStackPointerCallback getStackPointer = () {
 }();
 
 class StackSizePage extends StatelessWidget {
+  const StackSizePage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(
@@ -89,7 +91,7 @@ class StackSizePage extends StatelessWidget {
           Container(
             width: 200,
             height: 100,
-            child: ParentWidget(),
+            child: const ParentWidget(),
           ),
         ],
       ),
@@ -98,6 +100,8 @@ class StackSizePage extends StatelessWidget {
 }
 
 class ParentWidget extends StatelessWidget {
+  const ParentWidget({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final int myStackSize = getStackPointer();

dev/benchmarks/macrobenchmarks/lib/src/text.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class TextPage extends StatelessWidget {
+  const TextPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(

dev/benchmarks/macrobenchmarks/lib/src/web/bench_text_layout.dart

@@ -271,7 +271,7 @@ class BenchBuildColorsGrid extends WidgetBuildRecorder {
   @override
   Widget createWidget() {
     _counter++;
-    return MaterialApp(home: ColorsDemo());
+    return const MaterialApp(home: ColorsDemo());
   }
 }
 
@@ -469,6 +469,8 @@ class PaletteTabView extends StatelessWidget {
 }
 
 class ColorsDemo extends StatelessWidget {
+  const ColorsDemo({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return DefaultTabController(

dev/benchmarks/macrobenchmarks/lib/src/web/bench_wrapbox_scroll.dart

@@ -84,7 +84,7 @@ class _MyHomePageState extends State<MyHomePage> {
 }
 
 class ProductPreview extends StatelessWidget {
-  const ProductPreview(this.previewIndex);
+  const ProductPreview(this.previewIndex, {Key key}) : super(key: key);
 
   final int previewIndex;
 

dev/benchmarks/macrobenchmarks/test/frame_policy.dart

@@ -17,7 +17,7 @@ void main() {
   testWidgets(
     'Frame Counter and Input Delay for benchmarkLive',
     (WidgetTester tester) async {
-      await tester.pumpWidget(MaterialApp(home: Scaffold(body: SimpleScroll())));
+      await tester.pumpWidget(const MaterialApp(home: Scaffold(body: SimpleScroll())));
       await tester.pumpAndSettle();
       final Offset location = tester.getCenter(find.byType(ListView));
       int frameCount = 0;

dev/benchmarks/microbenchmarks/lib/gestures/apps/button_matrix_app.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class ButtonMatrixApp extends StatefulWidget {
+  const ButtonMatrixApp({Key key}) : super(key: key);
+
   @override
   ButtonMatrixAppState createState() => ButtonMatrixAppState();
 }
@@ -48,5 +50,5 @@ class ButtonMatrixAppState extends State<ButtonMatrixApp> {
 }
 
 void main() {
-  runApp(ButtonMatrixApp());
+  runApp(const ButtonMatrixApp());
 }

dev/benchmarks/multiple_flutters/module/lib/main.dart

@@ -13,7 +13,7 @@ void topMain() => runApp(const MyApp(Colors.green));
 void bottomMain() => runApp(const MyApp(Colors.purple));
 
 class MyApp extends StatelessWidget {
-  const MyApp(this.color);
+  const MyApp(this.color, {Key key}) : super(key: key);
 
   final Color color;
 

dev/benchmarks/test_apps/stocks/lib/main.dart

@@ -20,6 +20,8 @@ import 'stock_symbol_viewer.dart';
 import 'stock_types.dart';
 
 class StocksApp extends StatefulWidget {
+  const StocksApp({Key key}) : super(key: key);
+
   @override
   StocksAppState createState() => StocksAppState();
 }
@@ -109,5 +111,5 @@ class StocksAppState extends State<StocksApp> {
 }
 
 void main() {
-  runApp(StocksApp());
+  runApp(const StocksApp());
 }

dev/benchmarks/test_apps/stocks/lib/stock_home.dart

@@ -52,7 +52,7 @@ class _NotImplementedDialog extends StatelessWidget {
 }
 
 class StockHome extends StatefulWidget {
-  const StockHome(this.stocks, this.configuration, this.updater);
+  const StockHome(this.stocks, this.configuration, this.updater, {Key key}) : super(key: key);
 
   final StockData stocks;
   final StockConfiguration configuration;

dev/benchmarks/test_apps/stocks/lib/stock_settings.dart

@@ -7,7 +7,7 @@ import 'package:flutter/material.dart';
 import 'stock_types.dart';
 
 class StockSettings extends StatefulWidget {
-  const StockSettings(this.configuration, this.updater);
+  const StockSettings(this.configuration, this.updater, {Key key}) : super(key: key);
 
   final StockConfiguration configuration;
   final ValueChanged<StockConfiguration> updater;

dev/benchmarks/test_apps/stocks/lib/stock_symbol_viewer.dart

@@ -65,7 +65,7 @@ class _StockSymbolView extends StatelessWidget {
 }
 
 class StockSymbolPage extends StatelessWidget {
-  const StockSymbolPage({ this.symbol, this.stocks });
+  const StockSymbolPage({ Key key, this.symbol, this.stocks }) : super(key: key);
 
   final String symbol;
   final StockData stocks;
@@ -113,7 +113,7 @@ class StockSymbolPage extends StatelessWidget {
 }
 
 class StockSymbolBottomSheet extends StatelessWidget {
-  const StockSymbolBottomSheet({ this.stock });
+  const StockSymbolBottomSheet({ Key key, this.stock }) : super(key: key);
 
   final Stock stock;
 

dev/integration_tests/abstract_method_smoke_test/lib/main.dart

@@ -9,11 +9,13 @@ Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
   const MethodChannel channel = MethodChannel('com.example.abstract_method_smoke_test');
   await channel.invokeMethod<void>('show_keyboard');
-  runApp(MyApp());
+  runApp(const MyApp());
   print('Test suceeded');
 }
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -21,12 +23,14 @@ class MyApp extends StatelessWidget {
       theme: ThemeData(
         primarySwatch: Colors.blue,
       ),
-      home: HomePage(),
+      home: const HomePage(),
     );
   }
 }
 
 class HomePage extends StatefulWidget {
+  const HomePage({Key key}) : super(key: key);
+
   @override
   _HomePage createState() => _HomePage();
 }
@@ -40,7 +44,7 @@ class _HomePage extends State<HomePage> {
     // https://github.com/flutter/flutter/issues/40126
     WidgetsBinding.instance.addPostFrameCallback((_) async {
       Navigator.of(context).push(
-          MaterialPageRoute<void>(builder: (_) => SecondPage()));
+          MaterialPageRoute<void>(builder: (_) => const SecondPage()));
     });
   }
 
@@ -51,6 +55,8 @@ class _HomePage extends State<HomePage> {
 }
 
 class SecondPage extends StatelessWidget {
+  const SecondPage({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/integration_tests/android_semantics_testing/lib/main.dart

@@ -43,14 +43,14 @@ Future<String> dataHandler(String message) async {
 }
 
 Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
-  selectionControlsRoute : (BuildContext context) => SelectionControlsPage(),
-  popupControlsRoute : (BuildContext context) => PopupControlsPage(),
-  textFieldRoute : (BuildContext context) => TextFieldPage(),
-  headingsRoute: (BuildContext context) => HeadingsPage(),
+  selectionControlsRoute : (BuildContext context) => const SelectionControlsPage(),
+  popupControlsRoute : (BuildContext context) => const PopupControlsPage(),
+  textFieldRoute : (BuildContext context) => const TextFieldPage(),
+  headingsRoute: (BuildContext context) => const HeadingsPage(),
 };
 
 class TestApp extends StatelessWidget {
-  const TestApp();
+  const TestApp({Key key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {

dev/integration_tests/android_semantics_testing/lib/src/tests/controls_page.dart

@@ -9,6 +9,8 @@ export 'controls_constants.dart';
 
 /// A test page with a checkbox, three radio buttons, and a switch.
 class SelectionControlsPage extends StatefulWidget {
+  const SelectionControlsPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _SelectionControlsPageState();
 }

dev/integration_tests/android_semantics_testing/lib/src/tests/headings_page.dart

@@ -9,6 +9,8 @@ export 'headings_constants.dart';
 
 /// A test page with an app bar and some body text for testing heading flags.
 class HeadingsPage extends StatelessWidget {
+  const HeadingsPage({Key key}) : super(key: key);
+
   static const ValueKey<String> _appBarTitleKey = ValueKey<String>(appBarTitleKeyValue);
   static const ValueKey<String> _bodyTextKey = ValueKey<String>(bodyTextKeyValue);
 

dev/integration_tests/android_semantics_testing/lib/src/tests/popup_page.dart

@@ -10,6 +10,8 @@ export 'popup_constants.dart';
 
 /// A page with a popup menu, a dropdown menu, and a modal alert.
 class PopupControlsPage extends StatefulWidget {
+  const PopupControlsPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _PopupControlsPageState();
 }

dev/integration_tests/android_semantics_testing/lib/src/tests/text_field_page.dart

@@ -10,6 +10,8 @@ export 'text_field_constants.dart';
 
 /// A page with a normal text field and a password field.
 class TextFieldPage extends StatefulWidget {
+  const TextFieldPage({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _TextFieldPageState();
 }

dev/integration_tests/android_views/lib/main.dart

@@ -16,10 +16,12 @@ final List<PageWidget> _allPages = <PageWidget>[
 
 void main() {
   enableFlutterDriverExtension(handler: driverDataHandler.handleMessage);
-  runApp(MaterialApp(home: Home()));
+  runApp(const MaterialApp(home: Home()));
 }
 
 class Home extends StatelessWidget {
+  const Home({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/integration_tests/android_views/lib/motion_events_page.dart

@@ -18,12 +18,12 @@ MethodChannel channel = const MethodChannel('android_views_integration');
 const String kEventsFileName = 'touchEvents';
 
 class MotionEventsPage extends PageWidget {
-  const MotionEventsPage()
-      : super('Motion Event Tests', const ValueKey<String>('MotionEventsListTile'));
+  const MotionEventsPage({Key key})
+      : super('Motion Event Tests', const ValueKey<String>('MotionEventsListTile'), key: key);
 
   @override
   Widget build(BuildContext context) {
-    return MotionEventsBody();
+    return const MotionEventsBody();
   }
 }
 
@@ -44,6 +44,8 @@ class FutureDataHandler {
 FutureDataHandler driverDataHandler = FutureDataHandler();
 
 class MotionEventsBody extends StatefulWidget {
+  const MotionEventsBody({Key key}) : super(key: key);
+
   @override
   State createState() => MotionEventsBodyState();
 }
@@ -251,7 +253,7 @@ class MotionEventsBodyState extends State<MotionEventsBody> {
 }
 
 class TouchEventDiff extends StatelessWidget {
-  const TouchEventDiff(this.originalEvent, this.synthesizedEvent);
+  const TouchEventDiff(this.originalEvent, this.synthesizedEvent, {Key key}) : super(key: key);
 
   final Map<String, dynamic> originalEvent;
   final Map<String, dynamic> synthesizedEvent;

dev/integration_tests/android_views/lib/page.dart

@@ -8,7 +8,7 @@ import 'package:flutter/material.dart';
 //
 /// A testing page has to override this in order to be put as one of the items in the main page.
 abstract class PageWidget extends StatelessWidget {
-  const PageWidget(this.title, this.tileKey);
+  const PageWidget(this.title, this.tileKey, {Key key}) : super(key: key);
 
   /// The title of the testing page
   ///

dev/integration_tests/android_views/lib/wm_integrations.dart

@@ -10,14 +10,16 @@ import 'package:flutter/services.dart';
 import 'page.dart';
 
 class WindowManagerIntegrationsPage extends PageWidget {
-  const WindowManagerIntegrationsPage()
-      : super('Window Manager Integrations Tests', const ValueKey<String>('WmIntegrationsListTile'));
+  const WindowManagerIntegrationsPage({Key key})
+      : super('Window Manager Integrations Tests', const ValueKey<String>('WmIntegrationsListTile'), key: key);
 
   @override
-  Widget build(BuildContext context) => WindowManagerBody();
+  Widget build(BuildContext context) => const WindowManagerBody();
 }
 
 class WindowManagerBody extends StatefulWidget {
+  const WindowManagerBody({Key key}) : super(key: key);
+
   @override
   State<WindowManagerBody> createState() => WindowManagerBodyState();
 }

dev/integration_tests/channels/lib/main.dart

@@ -15,10 +15,12 @@ import 'src/test_step.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(TestApp());
+  runApp(const TestApp());
 }
 
 class TestApp extends StatefulWidget {
+  const TestApp({Key key}) : super(key: key);
+
   @override
   _TestAppState createState() => _TestAppState();
 }

dev/integration_tests/external_ui/lib/main.dart

@@ -11,10 +11,12 @@ import 'package:flutter_driver/driver_extension.dart';
 void main() {
   enableFlutterDriverExtension();
   debugPrint('Application starting...');
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 class MyApp extends StatefulWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   State createState() => MyAppState();
 }

dev/integration_tests/flavors/lib/main.dart

@@ -8,10 +8,12 @@ import 'package:flutter_driver/driver_extension.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(Center(child: Flavor()));
+  runApp(const Center(child: Flavor()));
 }
 
 class Flavor extends StatefulWidget {
+  const Flavor({Key key}) : super(key: key);
+
   @override
   _FlavorState createState() => _FlavorState();
 }

dev/integration_tests/flutter_gallery/lib/demo/calculator/home.dart

@@ -138,7 +138,7 @@ class _CalculatorState extends State<Calculator> {
 }
 
 class CalcDisplay extends StatelessWidget {
-  const CalcDisplay({ this.content });
+  const CalcDisplay({ Key? key, this.content}) : super(key: key);
 
   final String? content;
 
@@ -154,7 +154,7 @@ class CalcDisplay extends StatelessWidget {
 }
 
 class KeyPad extends StatelessWidget {
-  const KeyPad({ this.calcState });
+  const KeyPad({ Key? key, this.calcState }) : super(key: key);
 
   final _CalculatorState? calcState;
 
@@ -222,7 +222,7 @@ class KeyPad extends StatelessWidget {
 }
 
 class KeyRow extends StatelessWidget {
-  const KeyRow(this.keys);
+  const KeyRow(this.keys, {Key? key}) : super(key: key);
 
   final List<Widget> keys;
 
@@ -238,7 +238,7 @@ class KeyRow extends StatelessWidget {
 }
 
 class CalcKey extends StatelessWidget {
-  const CalcKey(this.text, this.onTap);
+  const CalcKey(this.text, this.onTap, {Key? key}) : super(key: key);
 
   final String text;
   final GestureTapCallback onTap;
@@ -265,8 +265,8 @@ class CalcKey extends StatelessWidget {
 }
 
 class NumberKey extends CalcKey {
-  NumberKey(int value, _CalculatorState? calcState)
+  NumberKey(int value, _CalculatorState? calcState, {Key? key})
     : super('$value', () {
         calcState!.handleNumberTap(value);
-      });
+      }, key: key);
 }

dev/integration_tests/flutter_gallery/lib/demo/colors_demo.dart

@@ -120,6 +120,8 @@ class PaletteTabView extends StatelessWidget {
 }
 
 class ColorsDemo extends StatelessWidget {
+  const ColorsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/colors';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/contacts_demo.dart

@@ -86,6 +86,8 @@ class _ContactItem extends StatelessWidget {
 }
 
 class ContactsDemo extends StatefulWidget {
+  const ContactsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/contacts';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_activity_indicator_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoProgressIndicatorDemo extends StatelessWidget {
+  const CupertinoProgressIndicatorDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/progress_indicator';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_alert_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoAlertDemo extends StatefulWidget {
+  const CupertinoAlertDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/alert';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_buttons_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoButtonsDemo extends StatefulWidget {
+  const CupertinoButtonsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/buttons';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_navigation_demo.dart

@@ -32,13 +32,14 @@ const List<String> coolColorNames = <String>[
 const int _kChildCount = 50;
 
 class CupertinoNavigationDemo extends StatelessWidget {
-  CupertinoNavigationDemo({ this.randomSeed })
+  CupertinoNavigationDemo({ Key? key, this.randomSeed })
       : colorItems = List<Color>.generate(_kChildCount, (int index) {
           return coolColors[math.Random(randomSeed).nextInt(coolColors.length)];
         }) ,
         colorNameItems = List<String>.generate(_kChildCount, (int index) {
           return coolColorNames[math.Random(randomSeed).nextInt(coolColorNames.length)];
-        });
+        }),
+        super(key: key);
 
   static const String routeName = '/cupertino/navigation';
 
@@ -85,12 +86,12 @@ class CupertinoNavigationDemo extends StatelessWidget {
                 );
               case 1:
                 return CupertinoTabView(
-                  builder: (BuildContext context) => CupertinoDemoTab2(),
+                  builder: (BuildContext context) => const CupertinoDemoTab2(),
                   defaultTitle: 'Support Chat',
                 );
               case 2:
                 return CupertinoTabView(
-                  builder: (BuildContext context) => CupertinoDemoTab3(),
+                  builder: (BuildContext context) => const CupertinoDemoTab3(),
                   defaultTitle: 'Account',
                 );
             }
@@ -104,7 +105,7 @@ class CupertinoNavigationDemo extends StatelessWidget {
 }
 
 class ExitButton extends StatelessWidget {
-  const ExitButton();
+  const ExitButton({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -134,10 +135,11 @@ final Widget trailingButtons = Row(
 
 class CupertinoDemoTab1 extends StatelessWidget {
   const CupertinoDemoTab1({
+    Key? key,
     this.colorItems,
     this.colorNameItems,
     this.randomSeed,
-  });
+  }) : super(key: key);
 
   final List<Color>? colorItems;
   final List<String>? colorNameItems;
@@ -184,12 +186,13 @@ class CupertinoDemoTab1 extends StatelessWidget {
 
 class Tab1RowItem extends StatelessWidget {
   const Tab1RowItem({
+    Key? key,
     this.index,
     this.lastItem,
     this.color,
     this.colorName,
     this.randomSeed,
-  });
+  }) : super(key: key);
 
   final int? index;
   final bool? lastItem;
@@ -287,7 +290,7 @@ class Tab1RowItem extends StatelessWidget {
 }
 
 class Tab1ItemPage extends StatefulWidget {
-  const Tab1ItemPage({this.color, this.colorName, this.index, this.randomSeed});
+  const Tab1ItemPage({Key? key, this.color, this.colorName, this.index, this.randomSeed}) : super(key: key);
 
   final Color? color;
   final String? colorName;
@@ -441,6 +444,8 @@ class Tab1ItemPageState extends State<Tab1ItemPage> {
 }
 
 class CupertinoDemoTab2 extends StatelessWidget {
+  const CupertinoDemoTab2({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return CupertinoPageScaffold(
@@ -450,7 +455,7 @@ class CupertinoDemoTab2 extends StatelessWidget {
       child: CupertinoScrollbar(
         child: ListView(
           children: <Widget>[
-            CupertinoUserInterfaceLevel(
+            const CupertinoUserInterfaceLevel(
               data: CupertinoUserInterfaceLevelData.elevated,
               child: Tab2Header(),
             ),
@@ -463,6 +468,8 @@ class CupertinoDemoTab2 extends StatelessWidget {
 }
 
 class Tab2Header extends StatelessWidget {
+  const Tab2Header({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Padding(
@@ -589,7 +596,7 @@ enum Tab2ConversationBubbleColor {
 }
 
 class Tab2ConversationBubble extends StatelessWidget {
-  const Tab2ConversationBubble({this.text, this.color});
+  const Tab2ConversationBubble({Key? key, this.text, this.color}) : super(key: key);
 
   final String? text;
   final Tab2ConversationBubbleColor? color;
@@ -633,7 +640,7 @@ class Tab2ConversationBubble extends StatelessWidget {
 }
 
 class Tab2ConversationAvatar extends StatelessWidget {
-  const Tab2ConversationAvatar({this.text, this.color});
+  const Tab2ConversationAvatar({Key? key, this.text, this.color}) : super(key: key);
 
   final String? text;
   final Color? color;
@@ -672,7 +679,7 @@ class Tab2ConversationAvatar extends StatelessWidget {
 }
 
 class Tab2ConversationRow extends StatelessWidget {
-  const Tab2ConversationRow({this.avatar, this.text});
+  const Tab2ConversationRow({Key? key, this.avatar, this.text}) : super(key: key);
 
   final Tab2ConversationAvatar? avatar;
   final String? text;
@@ -742,6 +749,8 @@ List<Widget> buildTab2Conversation() {
 }
 
 class CupertinoDemoTab3 extends StatelessWidget {
+  const CupertinoDemoTab3({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return CupertinoPageScaffold(
@@ -755,7 +764,7 @@ class CupertinoDemoTab3 extends StatelessWidget {
               Navigator.of(context, rootNavigator: true).push(
                 CupertinoPageRoute<bool>(
                   fullscreenDialog: true,
-                  builder: (BuildContext context) => Tab3Dialog(),
+                  builder: (BuildContext context) => const Tab3Dialog(),
                 ),
               );
             },
@@ -792,6 +801,8 @@ class CupertinoDemoTab3 extends StatelessWidget {
 }
 
 class Tab3Dialog extends StatelessWidget {
+  const Tab3Dialog({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return CupertinoPageScaffold(

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_picker_demo.dart

@@ -12,6 +12,8 @@ const double _kPickerSheetHeight = 216.0;
 const double _kPickerItemHeight = 32.0;
 
 class CupertinoPickerDemo extends StatefulWidget {
+  const CupertinoPickerDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/picker';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_refresh_demo.dart

@@ -9,6 +9,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoRefreshControlDemo extends StatefulWidget {
+  const CupertinoRefreshControlDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/refresh';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_segmented_control_demo.dart

@@ -12,6 +12,8 @@ const Color _kKeyPenumbraOpacity = Color(0x24000000); // alpha = 0.14
 const Color _kAmbientShadowOpacity = Color(0x1F000000); // alpha = 0.12
 
 class CupertinoSegmentedControlDemo extends StatefulWidget {
+  const CupertinoSegmentedControlDemo({Key? key}) : super(key: key);
+
   static const String routeName = 'cupertino/segmented_control';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_slider_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoSliderDemo extends StatefulWidget {
+  const CupertinoSliderDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/slider';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_switch_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/cupertino.dart';
 import '../../gallery/demo.dart';
 
 class CupertinoSwitchDemo extends StatefulWidget {
+  const CupertinoSwitchDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/switch';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_text_field_demo.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/cupertino.dart';
 
 class CupertinoTextFieldDemo extends StatefulWidget {
+  const CupertinoTextFieldDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/cupertino/text_fields';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/fortnightly/fortnightly.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class FortnightlyDemo extends StatelessWidget {
+  const FortnightlyDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/fortnightly';
 
   @override
@@ -15,7 +17,7 @@ class FortnightlyDemo extends StatelessWidget {
       home: Scaffold(
         body: Stack(
           children: <Widget>[
-            FruitPage(),
+            const FruitPage(),
             SafeArea(
               child: ShortAppBar(
                 onBackPressed: () {
@@ -31,7 +33,7 @@ class FortnightlyDemo extends StatelessWidget {
 }
 
 class ShortAppBar extends StatelessWidget {
-  const ShortAppBar({ this.onBackPressed });
+  const ShortAppBar({ Key? key, this.onBackPressed }) : super(key: key);
 
   final VoidCallback? onBackPressed;
 
@@ -66,6 +68,8 @@ class ShortAppBar extends StatelessWidget {
 }
 
 class FruitPage extends StatelessWidget {
+  const FruitPage({Key? key}) : super(key: key);
+
   static final String paragraph1 = '''
 Have you ever held a quince? It's strange;
 covered in a fuzz somewhere between peach skin and a spider web. And it's

dev/integration_tests/flutter_gallery/lib/demo/images_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../gallery/demo.dart';
 
 class ImagesDemo extends StatelessWidget {
+  const ImagesDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/images';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/backdrop_demo.dart

@@ -239,6 +239,8 @@ class BackdropTitle extends AnimatedWidget {
 
 // This widget is essentially the backdrop itself.
 class BackdropDemo extends StatefulWidget {
+  const BackdropDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/backdrop';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/bottom_app_bar_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class BottomAppBarDemo extends StatefulWidget {
+  const BottomAppBarDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/bottom_app_bar';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/bottom_navigation_demo.dart

@@ -74,6 +74,8 @@ class NavigationIconView {
 }
 
 class CustomIcon extends StatelessWidget {
+  const CustomIcon({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final IconThemeData iconTheme = IconTheme.of(context);
@@ -87,6 +89,8 @@ class CustomIcon extends StatelessWidget {
 }
 
 class CustomInactiveIcon extends StatelessWidget {
+  const CustomInactiveIcon({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     final IconThemeData iconTheme = IconTheme.of(context);
@@ -102,6 +106,8 @@ class CustomInactiveIcon extends StatelessWidget {
 }
 
 class BottomNavigationDemo extends StatefulWidget {
+  const BottomNavigationDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/bottom_navigation';
 
   @override
@@ -125,8 +131,8 @@ class _BottomNavigationDemoState extends State<BottomNavigationDemo>
         vsync: this,
       ),
       NavigationIconView(
-        activeIcon: CustomIcon(),
-        icon: CustomInactiveIcon(),
+        activeIcon: const CustomIcon(),
+        icon: const CustomInactiveIcon(),
         title: 'Box',
         color: Colors.deepOrange,
         vsync: this,

dev/integration_tests/flutter_gallery/lib/demo/material/buttons_demo.dart

@@ -46,6 +46,8 @@ const String _actionText =
 const String _actionCode = 'buttons_action';
 
 class ButtonsDemo extends StatefulWidget {
+  const ButtonsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/buttons';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/cards_demo.dart

@@ -335,6 +335,8 @@ class TravelDestinationContent extends StatelessWidget {
 }
 
 class CardsDemo extends StatefulWidget {
+  const CardsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/cards';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/chip_demo.dart

@@ -135,6 +135,8 @@ class _ChipsTile extends StatelessWidget {
 }
 
 class ChipDemo extends StatefulWidget {
+  const ChipDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/chip';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/data_table_demo.dart

@@ -142,6 +142,8 @@ class DessertDataSource extends DataTableSource {
 }
 
 class DataTableDemo extends StatefulWidget {
+  const DataTableDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/data-table';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/date_and_time_picker_demo.dart

@@ -113,6 +113,8 @@ class _DateTimePicker extends StatelessWidget {
 }
 
 class DateAndTimePickerDemo extends StatefulWidget {
+  const DateAndTimePickerDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/date-and-time-pickers';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/dialog_demo.dart

@@ -48,6 +48,8 @@ class DialogDemoItem extends StatelessWidget {
 }
 
 class DialogDemo extends StatefulWidget {
+  const DialogDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/dialog';
 
   @override
@@ -192,7 +194,7 @@ class DialogDemoState extends State<DialogDemo> {
             child: const Text('FULLSCREEN'),
             onPressed: () {
               Navigator.push(context, MaterialPageRoute<DismissDialogAction>(
-                builder: (BuildContext context) => FullScreenDialogDemo(),
+                builder: (BuildContext context) => const FullScreenDialogDemo(),
                 fullscreenDialog: true,
               ));
             },

dev/integration_tests/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -13,6 +13,8 @@ const String _kAsset2 = 'people/square/sandra.png';
 const String _kGalleryAssetsPackage = 'flutter_gallery_assets';
 
 class DrawerDemo extends StatefulWidget {
+  const DrawerDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/drawer';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/elevation_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ElevationDemo extends StatefulWidget {
+  const ElevationDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/elevation';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/expansion_panels_demo.dart

@@ -18,11 +18,12 @@ typedef ValueToString<T> = String? Function(T value);
 
 class DualHeaderWithHint extends StatelessWidget {
   const DualHeaderWithHint({
+    Key? key,
     this.name,
     this.value,
     this.hint,
     this.showHint,
-  });
+  }) : super(key: key);
 
   final String? name;
   final String? value;
@@ -80,11 +81,12 @@ class DualHeaderWithHint extends StatelessWidget {
 
 class CollapsibleBody extends StatelessWidget {
   const CollapsibleBody({
+    Key? key,
     this.margin = EdgeInsets.zero,
     this.child,
     this.onSave,
     this.onCancel,
-  });
+  }) : super(key: key);
 
   final EdgeInsets margin;
   final Widget? child;
@@ -175,6 +177,8 @@ class DemoItem<T> {
 }
 
 class ExpansionPanelsDemo extends StatefulWidget {
+  const ExpansionPanelsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/expansion_panels';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/expansion_tile_list_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ExpansionTileListDemo extends StatelessWidget {
+  const ExpansionTileListDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/expansion-tile-list';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/full_screen_dialog_demo.dart

@@ -93,6 +93,8 @@ class DateTimeItem extends StatelessWidget {
 }
 
 class FullScreenDialogDemo extends StatefulWidget {
+  const FullScreenDialogDemo({Key? key}) : super(key: key);
+
   @override
   FullScreenDialogDemoState createState() => FullScreenDialogDemoState();
 }

dev/integration_tests/flutter_gallery/lib/demo/material/icons_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class IconsDemo extends StatefulWidget {
+  const IconsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/icons';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/modal_bottom_sheet_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ModalBottomSheetDemo extends StatelessWidget {
+  const ModalBottomSheetDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/modal-bottom-sheet';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/page_selector_demo.dart

@@ -74,6 +74,8 @@ class _PageSelector extends StatelessWidget {
 }
 
 class PageSelectorDemo extends StatelessWidget {
+  const PageSelectorDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/page-selector';
   static final List<Icon> icons = <Icon>[
     const Icon(Icons.event, semanticLabel: 'Event'),

dev/integration_tests/flutter_gallery/lib/demo/material/persistent_bottom_sheet_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class PersistentBottomSheetDemo extends StatefulWidget {
+  const PersistentBottomSheetDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/persistent-bottom-sheet';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/progress_indicator_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class ProgressIndicatorDemo extends StatefulWidget {
+  const ProgressIndicatorDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/progress-indicator';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/scrollable_tabs_demo.dart

@@ -36,6 +36,8 @@ const List<_Page> _allPages = <_Page>[
 ];
 
 class ScrollableTabsDemo extends StatefulWidget {
+  const ScrollableTabsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/scrollable-tabs';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/search_demo.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class SearchDemo extends StatefulWidget {
+  const SearchDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/search';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/selection_controls_demo.dart

@@ -28,6 +28,8 @@ const String _switchText =
 const String _switchCode = 'selectioncontrols_switch';
 
 class SelectionControlsDemo extends StatefulWidget {
+  const SelectionControlsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/selection-controls';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/slider_demo.dart

@@ -9,6 +9,8 @@ import 'package:flutter/material.dart';
 import '../../gallery/demo.dart';
 
 class SliderDemo extends StatefulWidget {
+  const SliderDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/slider';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/tabs_demo.dart

@@ -138,6 +138,8 @@ class _CardDataItem extends StatelessWidget {
 }
 
 class TabsDemo extends StatelessWidget {
+  const TabsDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/tabs';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/tabs_fab_demo.dart

@@ -35,6 +35,8 @@ final List<_Page> _allPages = <_Page>[
 ];
 
 class TabsFabDemo extends StatefulWidget {
+  const TabsFabDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/material/tabs-fab';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -26,6 +26,7 @@ class PersonData {
 
 class PasswordField extends StatefulWidget {
   const PasswordField({
+    Key? key,
     this.fieldKey,
     this.hintText,
     this.labelText,
@@ -33,7 +34,7 @@ class PasswordField extends StatefulWidget {
     this.onSaved,
     this.validator,
     this.onFieldSubmitted,
-  });
+  }) : super(key: key);
 
   final Key? fieldKey;
   final String? hintText;

dev/integration_tests/flutter_gallery/lib/demo/material/tooltip_demo.dart

@@ -12,6 +12,7 @@ const String _introText =
   'apps accessible, like screen readers.';
 
 class TooltipDemo extends StatelessWidget {
+  const TooltipDemo({Key? key}) : super(key: key);
 
   static const String routeName = '/material/tooltips';
 

dev/integration_tests/flutter_gallery/lib/demo/pesto_demo.dart

@@ -10,7 +10,7 @@ class PestoDemo extends StatelessWidget {
   static const String routeName = '/pesto';
 
   @override
-  Widget build(BuildContext context) => PestoHome();
+  Widget build(BuildContext context) => const PestoHome();
 }
 
 
@@ -29,6 +29,8 @@ final ThemeData _kTheme = ThemeData(
 );
 
 class PestoHome extends StatelessWidget {
+  const PestoHome({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const RecipeGridPage(recipes: kPestoRecipes);
@@ -36,6 +38,8 @@ class PestoHome extends StatelessWidget {
 }
 
 class PestoFavorites extends StatelessWidget {
+  const PestoFavorites({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return RecipeGridPage(recipes: _favoriteRecipes.toList());
@@ -167,7 +171,7 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
   void showFavoritesPage(BuildContext context) {
     Navigator.push(context, MaterialPageRoute<void>(
       settings: const RouteSettings(name: '/pesto/favorites'),
-      builder: (BuildContext context) => PestoFavorites(),
+      builder: (BuildContext context) => const PestoFavorites(),
     ));
   }
 
@@ -185,7 +189,7 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
 }
 
 class PestoLogo extends StatefulWidget {
-  const PestoLogo({this.height, this.t});
+  const PestoLogo({Key? key, this.height, this.t}) : super(key: key);
 
   final double? height;
   final double? t;

dev/integration_tests/flutter_gallery/lib/demo/shrine/app.dart

@@ -13,6 +13,8 @@ import 'package:flutter_gallery/demo/shrine/login.dart';
 import 'package:flutter_gallery/demo/shrine/supplemental/cut_corners_border.dart';
 
 class ShrineApp extends StatefulWidget {
+  const ShrineApp({Key? key}) : super(key: key);
+
   @override
   _ShrineAppState createState() => _ShrineAppState();
 }
@@ -62,7 +64,7 @@ Route<dynamic>? _getRoute(RouteSettings settings) {
 
   return MaterialPageRoute<void>(
     settings: settings,
-    builder: (BuildContext context) => LoginPage(),
+    builder: (BuildContext context) => const LoginPage(),
     fullscreenDialog: true,
   );
 }

dev/integration_tests/flutter_gallery/lib/demo/shrine/backdrop.dart

@@ -198,12 +198,13 @@ class _BackdropTitle extends AnimatedWidget {
 /// front or back layer is showing.
 class Backdrop extends StatefulWidget {
   const Backdrop({
+    Key? key,
     required this.frontLayer,
     required this.backLayer,
     required this.frontTitle,
     required this.backTitle,
     required this.controller,
-  });
+  }) : super(key: key);
 
   final Widget frontLayer;
   final Widget backLayer;
@@ -355,7 +356,7 @@ class _BackdropState extends State<Backdrop> with SingleTickerProviderStateMixin
           onPressed: () {
             Navigator.push<void>(
               context,
-              MaterialPageRoute<void>(builder: (BuildContext context) => LoginPage()),
+              MaterialPageRoute<void>(builder: (BuildContext context) => const LoginPage()),
             );
           },
         ),
@@ -364,7 +365,7 @@ class _BackdropState extends State<Backdrop> with SingleTickerProviderStateMixin
           onPressed: () {
             Navigator.push<void>(
               context,
-              MaterialPageRoute<void>(builder: (BuildContext context) => LoginPage()),
+              MaterialPageRoute<void>(builder: (BuildContext context) => const LoginPage()),
             );
           },
         ),

dev/integration_tests/flutter_gallery/lib/demo/shrine/expanding_bottom_sheet.dart

@@ -286,9 +286,9 @@ class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with Ticker
                   width: numProducts > 3 ? _width - 94.0 : _width - 64.0,
                   height: _kCartHeight,
                   padding: const EdgeInsets.symmetric(vertical: 8.0),
-                  child: ProductThumbnailRow(),
+                  child: const ProductThumbnailRow(),
                 ),
-                ExtraProductsNumber(),
+                const ExtraProductsNumber(),
               ],
             ),
           ],
@@ -300,7 +300,7 @@ class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with Ticker
   Widget _buildShoppingCartPage() {
     return Opacity(
       opacity: _cartOpacityAnimation.value,
-      child: ShoppingCartPage(),
+      child: const ShoppingCartPage(),
     );
   }
 
@@ -404,6 +404,8 @@ class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with Ticker
 }
 
 class ProductThumbnailRow extends StatefulWidget {
+  const ProductThumbnailRow({Key? key}) : super(key: key);
+
   @override
   _ProductThumbnailRowState createState() => _ProductThumbnailRowState();
 }
@@ -511,6 +513,8 @@ class _ProductThumbnailRowState extends State<ProductThumbnailRow> {
 }
 
 class ExtraProductsNumber extends StatelessWidget {
+  const ExtraProductsNumber({Key? key}) : super(key: key);
+
   // Calculates the number to be displayed at the end of the row if there are
   // more than three products in the cart. This calculates overflow products,
   // including their duplicates (but not duplicates of products shown as
@@ -554,7 +558,7 @@ class ExtraProductsNumber extends StatelessWidget {
 }
 
 class ProductThumbnail extends StatelessWidget {
-  const ProductThumbnail(this.animation, this.opacityAnimation, this.product);
+  const ProductThumbnail(this.animation, this.opacityAnimation, this.product, {Key? key}) : super(key: key);
 
   final Animation<double> animation;
   final Animation<double> opacityAnimation;

dev/integration_tests/flutter_gallery/lib/demo/shrine/home.dart

@@ -12,7 +12,7 @@ import 'package:flutter_gallery/demo/shrine/model/product.dart';
 import 'package:flutter_gallery/demo/shrine/supplemental/asymmetric_view.dart';
 
 class ProductPage extends StatelessWidget {
-  const ProductPage({this.category = Category.all});
+  const ProductPage({Key? key, this.category = Category.all}) : super(key: key);
 
   final Category category;
 

dev/integration_tests/flutter_gallery/lib/demo/shrine/login.dart

@@ -7,6 +7,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter_gallery/demo/shrine/colors.dart';
 
 class LoginPage extends StatefulWidget {
+  const LoginPage({Key? key}) : super(key: key);
+
   @override
   _LoginPageState createState() => _LoginPageState();
 }

dev/integration_tests/flutter_gallery/lib/demo/shrine/shopping_cart.dart

@@ -14,6 +14,8 @@ import 'package:flutter_gallery/demo/shrine/model/product.dart';
 const double _leftColumnWidth = 60.0;
 
 class ShoppingCartPage extends StatefulWidget {
+  const ShoppingCartPage({Key? key}) : super(key: key);
+
   @override
   _ShoppingCartPageState createState() => _ShoppingCartPageState();
 }
@@ -103,7 +105,7 @@ class _ShoppingCartPageState extends State<ShoppingCartPage> {
 }
 
 class ShoppingCartSummary extends StatelessWidget {
-  const ShoppingCartSummary({this.model});
+  const ShoppingCartSummary({Key? key, this.model}) : super(key: key);
 
   final AppStateModel? model;
 
@@ -183,10 +185,11 @@ class ShoppingCartSummary extends StatelessWidget {
 
 class ShoppingCartRow extends StatelessWidget {
   const ShoppingCartRow({
+    Key? key,
     required this.product,
     required this.quantity,
     this.onPressed,
-  });
+  }) : super(key: key);
 
   final Product product;
   final int? quantity;

dev/integration_tests/flutter_gallery/lib/demo/shrine/supplemental/product_card.dart

@@ -10,8 +10,8 @@ import 'package:flutter_gallery/demo/shrine/model/app_state_model.dart';
 import 'package:flutter_gallery/demo/shrine/model/product.dart';
 
 class ProductCard extends StatelessWidget {
-  const ProductCard({ this.imageAspectRatio = 33 / 49, this.product })
-      : assert(imageAspectRatio > 0);
+  const ProductCard({ Key? key, this.imageAspectRatio = 33 / 49, this.product })
+      : assert(imageAspectRatio > 0), super(key: key);
 
   final double imageAspectRatio;
   final Product? product;

dev/integration_tests/flutter_gallery/lib/demo/shrine/supplemental/product_columns.dart

@@ -9,9 +9,10 @@ import 'package:flutter_gallery/demo/shrine/supplemental/product_card.dart';
 
 class TwoProductCardColumn extends StatelessWidget {
   const TwoProductCardColumn({
+    Key? key,
     required this.bottom,
     this.top,
-  });
+  }) : super(key: key);
 
   final Product? bottom, top;
 
@@ -57,7 +58,7 @@ class TwoProductCardColumn extends StatelessWidget {
 }
 
 class OneProductCardColumn extends StatelessWidget {
-  const OneProductCardColumn({this.product});
+  const OneProductCardColumn({Key? key, this.product}) : super(key: key);
 
   final Product? product;
 

dev/integration_tests/flutter_gallery/lib/demo/shrine_demo.dart

@@ -11,5 +11,5 @@ class ShrineDemo extends StatelessWidget {
   static const String routeName = '/shrine'; // Used by the Gallery app.
 
   @override
-  Widget build(BuildContext context) => ShrineApp();
+  Widget build(BuildContext context) => const ShrineApp();
 }

dev/integration_tests/flutter_gallery/lib/demo/transformations/transformations_demo_color_picker.dart

@@ -8,10 +8,11 @@ import 'package:flutter/material.dart';
 @immutable
 class ColorPicker extends StatelessWidget {
   const ColorPicker({
+    Key? key,
     required this.colors,
     required this.selectedColor,
     this.onColorSelection,
-  });
+  }) : super(key: key);
 
   final Set<Color> colors;
   final Color selectedColor;

dev/integration_tests/flutter_gallery/lib/demo/typography_demo.dart

@@ -39,6 +39,8 @@ class TextStyleItem extends StatelessWidget {
 }
 
 class TypographyDemo extends StatelessWidget {
+  const TypographyDemo({Key? key}) : super(key: key);
+
   static const String routeName = '/typography';
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/video_demo.dart

@@ -92,7 +92,7 @@ class VideoCard extends StatelessWidget {
 }
 
 class VideoPlayerLoading extends StatefulWidget {
-  const VideoPlayerLoading(this.controller);
+  const VideoPlayerLoading(this.controller, {Key? key}) : super(key: key);
 
   final VideoPlayerController? controller;
 
@@ -136,7 +136,7 @@ class _VideoPlayerLoadingState extends State<VideoPlayerLoading> {
 }
 
 class VideoPlayPause extends StatefulWidget {
-  const VideoPlayPause(this.controller);
+  const VideoPlayPause(this.controller, {Key? key}) : super(key: key);
 
   final VideoPlayerController? controller;
 
@@ -202,9 +202,10 @@ class _VideoPlayPauseState extends State<VideoPlayPause> {
 
 class FadeAnimation extends StatefulWidget {
   const FadeAnimation({
+    Key? key,
     this.child,
     this.duration = const Duration(milliseconds: 500),
-  });
+  }) : super(key: key);
 
   final Widget? child;
   final Duration duration;
@@ -264,9 +265,10 @@ class _FadeAnimationState extends State<FadeAnimation> with SingleTickerProvider
 
 class ConnectivityOverlay extends StatefulWidget {
   const ConnectivityOverlay({
+    Key? key,
     this.child,
     this.connectedCompleter,
-  });
+  }) : super(key: key);
 
   final Widget? child;
   final Completer<void>? connectedCompleter;

dev/integration_tests/flutter_gallery/lib/gallery/backdrop.dart

@@ -179,13 +179,14 @@ class _BackAppBar extends StatelessWidget {
 
 class Backdrop extends StatefulWidget {
   const Backdrop({
+    Key? key,
     this.frontAction,
     this.frontTitle,
     this.frontHeading,
     this.frontLayer,
     this.backTitle,
     this.backLayer,
-  });
+  }) : super(key: key);
 
   final Widget? frontAction;
   final Widget? frontTitle;

dev/integration_tests/flutter_gallery/lib/gallery/demo.dart

@@ -42,12 +42,13 @@ class ComponentDemoTabData {
 
 class TabbedComponentDemoScaffold extends StatelessWidget {
   const TabbedComponentDemoScaffold({
+    Key? key,
     this.title,
     this.demos,
     this.actions,
     this.isScrollable = true,
     this.showExampleCodeAction = true,
-  });
+  }) : super(key: key);
 
   final List<ComponentDemoTabData>? demos;
   final String? title;
@@ -147,7 +148,7 @@ class TabbedComponentDemoScaffold extends StatelessWidget {
 }
 
 class FullScreenCodeDialog extends StatefulWidget {
-  const FullScreenCodeDialog({ this.exampleCodeTag });
+  const FullScreenCodeDialog({ Key? key, this.exampleCodeTag }) : super(key: key);
 
   final String? exampleCodeTag;
 

dev/integration_tests/flutter_gallery/lib/gallery/demos.dart

@@ -104,7 +104,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.custom_typography,
       category: _kDemos,
       routeName: FortnightlyDemo.routeName,
-      buildRoute: (BuildContext context) => FortnightlyDemo(),
+      buildRoute: (BuildContext context) => const FortnightlyDemo(),
     ),
     GalleryDemo(
       title: 'Contact profile',
@@ -112,7 +112,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.account_box,
       category: _kDemos,
       routeName: ContactsDemo.routeName,
-      buildRoute: (BuildContext context) => ContactsDemo(),
+      buildRoute: (BuildContext context) => const ContactsDemo(),
     ),
     GalleryDemo(
       title: 'Animation',
@@ -146,7 +146,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.colors,
       category: _kStyle,
       routeName: ColorsDemo.routeName,
-      buildRoute: (BuildContext context) => ColorsDemo(),
+      buildRoute: (BuildContext context) => const ColorsDemo(),
     ),
     GalleryDemo(
       title: 'Typography',
@@ -154,7 +154,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.custom_typography,
       category: _kStyle,
       routeName: TypographyDemo.routeName,
-      buildRoute: (BuildContext context) => TypographyDemo(),
+      buildRoute: (BuildContext context) => const TypographyDemo(),
     ),
 
     // Material Components
@@ -164,7 +164,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.backdrop,
       category: _kMaterialComponents,
       routeName: BackdropDemo.routeName,
-      buildRoute: (BuildContext context) => BackdropDemo(),
+      buildRoute: (BuildContext context) => const BackdropDemo(),
     ),
     GalleryDemo(
       title: 'Banner',
@@ -182,7 +182,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: BottomAppBarDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/BottomAppBar-class.html',
-      buildRoute: (BuildContext context) => BottomAppBarDemo(),
+      buildRoute: (BuildContext context) => const BottomAppBarDemo(),
     ),
     GalleryDemo(
       title: 'Bottom navigation',
@@ -191,7 +191,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: BottomNavigationDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/BottomNavigationBar-class.html',
-      buildRoute: (BuildContext context) => BottomNavigationDemo(),
+      buildRoute: (BuildContext context) => const BottomNavigationDemo(),
     ),
     GalleryDemo(
       title: 'Bottom sheet: Modal',
@@ -200,7 +200,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: ModalBottomSheetDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/showModalBottomSheet.html',
-      buildRoute: (BuildContext context) => ModalBottomSheetDemo(),
+      buildRoute: (BuildContext context) => const ModalBottomSheetDemo(),
     ),
     GalleryDemo(
       title: 'Bottom sheet: Persistent',
@@ -209,7 +209,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: PersistentBottomSheetDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/ScaffoldState/showBottomSheet.html',
-      buildRoute: (BuildContext context) => PersistentBottomSheetDemo(),
+      buildRoute: (BuildContext context) => const PersistentBottomSheetDemo(),
     ),
     GalleryDemo(
       title: 'Buttons',
@@ -217,7 +217,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.generic_buttons,
       category: _kMaterialComponents,
       routeName: ButtonsDemo.routeName,
-      buildRoute: (BuildContext context) => ButtonsDemo(),
+      buildRoute: (BuildContext context) => const ButtonsDemo(),
     ),
     GalleryDemo(
       title: 'Buttons: Floating Action Button',
@@ -226,7 +226,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: TabsFabDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/FloatingActionButton-class.html',
-      buildRoute: (BuildContext context) => TabsFabDemo(),
+      buildRoute: (BuildContext context) => const TabsFabDemo(),
     ),
     GalleryDemo(
       title: 'Cards',
@@ -235,7 +235,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: CardsDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/Card-class.html',
-      buildRoute: (BuildContext context) => CardsDemo(),
+      buildRoute: (BuildContext context) => const CardsDemo(),
     ),
     GalleryDemo(
       title: 'Chips',
@@ -244,7 +244,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: ChipDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/Chip-class.html',
-      buildRoute: (BuildContext context) => ChipDemo(),
+      buildRoute: (BuildContext context) => const ChipDemo(),
     ),
     GalleryDemo(
       title: 'Data tables',
@@ -253,7 +253,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: DataTableDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/PaginatedDataTable-class.html',
-      buildRoute: (BuildContext context) => DataTableDemo(),
+      buildRoute: (BuildContext context) => const DataTableDemo(),
     ),
     GalleryDemo(
       title: 'Dialogs',
@@ -262,7 +262,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: DialogDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/showDialog.html',
-      buildRoute: (BuildContext context) => DialogDemo(),
+      buildRoute: (BuildContext context) => const DialogDemo(),
     ),
     GalleryDemo(
       title: 'Elevations',
@@ -272,7 +272,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: ElevationDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/Material/elevation.html',
-      buildRoute: (BuildContext context) => ElevationDemo(),
+      buildRoute: (BuildContext context) => const ElevationDemo(),
     ),
     GalleryDemo(
       title: 'Expand/collapse list control',
@@ -281,7 +281,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: ExpansionTileListDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/ExpansionTile-class.html',
-      buildRoute: (BuildContext context) => ExpansionTileListDemo(),
+      buildRoute: (BuildContext context) => const ExpansionTileListDemo(),
     ),
     GalleryDemo(
       title: 'Expansion panels',
@@ -290,7 +290,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: ExpansionPanelsDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/ExpansionPanel-class.html',
-      buildRoute: (BuildContext context) => ExpansionPanelsDemo(),
+      buildRoute: (BuildContext context) => const ExpansionPanelsDemo(),
     ),
     GalleryDemo(
       title: 'Grid',
@@ -308,7 +308,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: IconsDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/IconButton-class.html',
-      buildRoute: (BuildContext context) => IconsDemo(),
+      buildRoute: (BuildContext context) => const IconsDemo(),
     ),
     GalleryDemo(
       title: 'Lists',
@@ -353,7 +353,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: DrawerDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/Drawer-class.html',
-      buildRoute: (BuildContext context) => DrawerDemo(),
+      buildRoute: (BuildContext context) => const DrawerDemo(),
     ),
     GalleryDemo(
       title: 'Pagination',
@@ -362,7 +362,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: PageSelectorDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/TabBarView-class.html',
-      buildRoute: (BuildContext context) => PageSelectorDemo(),
+      buildRoute: (BuildContext context) => const PageSelectorDemo(),
     ),
     GalleryDemo(
       title: 'Pickers',
@@ -371,7 +371,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: DateAndTimePickerDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/showDatePicker.html',
-      buildRoute: (BuildContext context) => DateAndTimePickerDemo(),
+      buildRoute: (BuildContext context) => const DateAndTimePickerDemo(),
     ),
     GalleryDemo(
       title: 'Progress indicators',
@@ -380,7 +380,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: ProgressIndicatorDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/LinearProgressIndicator-class.html',
-      buildRoute: (BuildContext context) => ProgressIndicatorDemo(),
+      buildRoute: (BuildContext context) => const ProgressIndicatorDemo(),
     ),
     GalleryDemo(
       title: 'Pull to refresh',
@@ -398,7 +398,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: SearchDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/showSearch.html',
-      buildRoute: (BuildContext context) => SearchDemo(),
+      buildRoute: (BuildContext context) => const SearchDemo(),
     ),
     GalleryDemo(
       title: 'Selection controls',
@@ -406,7 +406,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.check_box,
       category: _kMaterialComponents,
       routeName: SelectionControlsDemo.routeName,
-      buildRoute: (BuildContext context) => SelectionControlsDemo(),
+      buildRoute: (BuildContext context) => const SelectionControlsDemo(),
     ),
     GalleryDemo(
       title: 'Sliders',
@@ -415,7 +415,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: SliderDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/Slider-class.html',
-      buildRoute: (BuildContext context) => SliderDemo(),
+      buildRoute: (BuildContext context) => const SliderDemo(),
     ),
     GalleryDemo(
       title: 'Snackbar',
@@ -433,7 +433,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: TabsDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/TabBarView-class.html',
-      buildRoute: (BuildContext context) => TabsDemo(),
+      buildRoute: (BuildContext context) => const TabsDemo(),
     ),
     GalleryDemo(
       title: 'Tabs: Scrolling',
@@ -442,7 +442,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.tabs,
       routeName: ScrollableTabsDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/TabBar-class.html',
-      buildRoute: (BuildContext context) => ScrollableTabsDemo(),
+      buildRoute: (BuildContext context) => const ScrollableTabsDemo(),
     ),
     GalleryDemo(
       title: 'Text fields',
@@ -460,7 +460,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kMaterialComponents,
       routeName: TooltipDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/material/Tooltip-class.html',
-      buildRoute: (BuildContext context) => TooltipDemo(),
+      buildRoute: (BuildContext context) => const TooltipDemo(),
     ),
 
     // Cupertino Components
@@ -470,7 +470,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoProgressIndicatorDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoActivityIndicator-class.html',
-      buildRoute: (BuildContext context) => CupertinoProgressIndicatorDemo(),
+      buildRoute: (BuildContext context) => const CupertinoProgressIndicatorDemo(),
     ),
     GalleryDemo(
       title: 'Alerts',
@@ -478,7 +478,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoAlertDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/showCupertinoDialog.html',
-      buildRoute: (BuildContext context) => CupertinoAlertDemo(),
+      buildRoute: (BuildContext context) => const CupertinoAlertDemo(),
     ),
     GalleryDemo(
       title: 'Buttons',
@@ -486,7 +486,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoButtonsDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoButton-class.html',
-      buildRoute: (BuildContext context) => CupertinoButtonsDemo(),
+      buildRoute: (BuildContext context) => const CupertinoButtonsDemo(),
     ),
     GalleryDemo(
       title: 'Navigation',
@@ -502,7 +502,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoPickerDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoPicker-class.html',
-      buildRoute: (BuildContext context) => CupertinoPickerDemo(),
+      buildRoute: (BuildContext context) => const CupertinoPickerDemo(),
     ),
     GalleryDemo(
       title: 'Pull to refresh',
@@ -510,7 +510,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoRefreshControlDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoSliverRefreshControl-class.html',
-      buildRoute: (BuildContext context) => CupertinoRefreshControlDemo(),
+      buildRoute: (BuildContext context) => const CupertinoRefreshControlDemo(),
     ),
     GalleryDemo(
       title: 'Segmented Control',
@@ -518,7 +518,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoSegmentedControlDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoSegmentedControl-class.html',
-      buildRoute: (BuildContext context) => CupertinoSegmentedControlDemo(),
+      buildRoute: (BuildContext context) => const CupertinoSegmentedControlDemo(),
     ),
     GalleryDemo(
       title: 'Sliders',
@@ -526,7 +526,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoSliderDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoSlider-class.html',
-      buildRoute: (BuildContext context) => CupertinoSliderDemo(),
+      buildRoute: (BuildContext context) => const CupertinoSliderDemo(),
     ),
     GalleryDemo(
       title: 'Switches',
@@ -534,14 +534,14 @@ List<GalleryDemo> _buildGalleryDemos() {
       category: _kCupertinoComponents,
       routeName: CupertinoSwitchDemo.routeName,
       documentationUrl: 'https://api.flutter.dev/flutter/cupertino/CupertinoSwitch-class.html',
-      buildRoute: (BuildContext context) => CupertinoSwitchDemo(),
+      buildRoute: (BuildContext context) => const CupertinoSwitchDemo(),
     ),
     GalleryDemo(
       title: 'Text Fields',
       icon: GalleryIcons.text_fields_alt,
       category: _kCupertinoComponents,
       routeName: CupertinoTextFieldDemo.routeName,
-      buildRoute: (BuildContext context) => CupertinoTextFieldDemo(),
+      buildRoute: (BuildContext context) => const CupertinoTextFieldDemo(),
     ),
 
     // Media
@@ -551,7 +551,7 @@ List<GalleryDemo> _buildGalleryDemos() {
       icon: GalleryIcons.animation,
       category: _kMedia,
       routeName: ImagesDemo.routeName,
-      buildRoute: (BuildContext context) => ImagesDemo(),
+      buildRoute: (BuildContext context) => const ImagesDemo(),
     ),
     GalleryDemo(
       title: 'Video',

dev/integration_tests/flutter_gallery/test/accessibility_test.dart

@@ -12,84 +12,84 @@ void main() {
   group('All material demos meet recommended tap target sizes', () {
     testWidgets('backdrop_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: BackdropDemo()));
+      await tester.pumpWidget(const MaterialApp(home: BackdropDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('bottom_app_bar_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: BottomAppBarDemo()));
+      await tester.pumpWidget(const MaterialApp(home: BottomAppBarDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('bottom_navigation_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: BottomNavigationDemo()));
+      await tester.pumpWidget(const MaterialApp(home: BottomNavigationDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('buttons_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ButtonsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ButtonsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('cards_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: CardsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: CardsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('chip_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ChipDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ChipDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     }, skip: true); // https://github.com/flutter/flutter/issues/42455
 
     testWidgets('data_table_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DataTableDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DataTableDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('date_and_time_picker_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DateAndTimePickerDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DateAndTimePickerDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('dialog_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DialogDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DialogDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('drawer_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DrawerDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DrawerDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('elevation_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ElevationDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ElevationDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('expansion_panels_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ExpansionPanelsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ExpansionPanelsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -103,7 +103,7 @@ void main() {
 
     testWidgets('icons_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: IconsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: IconsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -131,7 +131,7 @@ void main() {
 
     testWidgets('modal_bottom_sheet_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ModalBottomSheetDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ModalBottomSheetDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -145,21 +145,21 @@ void main() {
 
     testWidgets('page_selector_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: PageSelectorDemo()));
+      await tester.pumpWidget(const MaterialApp(home: PageSelectorDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('persistent_bottom_sheet_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: PersistentBottomSheetDemo()));
+      await tester.pumpWidget(const MaterialApp(home: PersistentBottomSheetDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('progress_indicator_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ProgressIndicatorDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ProgressIndicatorDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -173,28 +173,28 @@ void main() {
 
     testWidgets('scrollable_tabs_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ScrollableTabsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ScrollableTabsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('search_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: SearchDemo()));
+      await tester.pumpWidget(const MaterialApp(home: SearchDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('selection_controls_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: SelectionControlsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: SelectionControlsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('slider_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: SliderDemo()));
+      await tester.pumpWidget(const MaterialApp(home: SliderDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -208,14 +208,14 @@ void main() {
 
     testWidgets('tabs_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: TabsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: TabsDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('tabs_fab_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: TabsFabDemo()));
+      await tester.pumpWidget(const MaterialApp(home: TabsFabDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -229,14 +229,14 @@ void main() {
 
     testWidgets('tooltip_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: TooltipDemo()));
+      await tester.pumpWidget(const MaterialApp(home: TooltipDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('expansion_tile_list_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ExpansionTileListDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ExpansionTileListDemo()));
       await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
       handle.dispose();
     });
@@ -245,84 +245,84 @@ void main() {
   group('All material demos have labeled tap targets', () {
     testWidgets('backdrop_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: BackdropDemo()));
+      await tester.pumpWidget(const MaterialApp(home: BackdropDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('bottom_app_bar_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: BottomAppBarDemo()));
+      await tester.pumpWidget(const MaterialApp(home: BottomAppBarDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('bottom_navigation_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: BottomNavigationDemo()));
+      await tester.pumpWidget(const MaterialApp(home: BottomNavigationDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('buttons_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ButtonsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ButtonsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('cards_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: CardsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: CardsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('chip_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ChipDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ChipDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('data_table_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DataTableDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DataTableDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     }, skip: true); // DataTables are not accessible, https://github.com/flutter/flutter/issues/10830
 
     testWidgets('date_and_time_picker_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DateAndTimePickerDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DateAndTimePickerDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('dialog_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DialogDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DialogDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('drawer_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: DrawerDemo()));
+      await tester.pumpWidget(const MaterialApp(home: DrawerDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('elevation_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ElevationDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ElevationDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('expansion_panels_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ExpansionPanelsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ExpansionPanelsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -336,7 +336,7 @@ void main() {
 
     testWidgets('icons_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: IconsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: IconsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -364,7 +364,7 @@ void main() {
 
     testWidgets('modal_bottom_sheet_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ModalBottomSheetDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ModalBottomSheetDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -378,21 +378,21 @@ void main() {
 
     testWidgets('page_selector_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: PageSelectorDemo()));
+      await tester.pumpWidget(const MaterialApp(home: PageSelectorDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('persistent_bottom_sheet_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: PersistentBottomSheetDemo()));
+      await tester.pumpWidget(const MaterialApp(home: PersistentBottomSheetDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('progress_indicator_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ProgressIndicatorDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ProgressIndicatorDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -406,28 +406,28 @@ void main() {
 
     testWidgets('scrollable_tabs_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ScrollableTabsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ScrollableTabsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('search_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: SearchDemo()));
+      await tester.pumpWidget(const MaterialApp(home: SearchDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('selection_controls_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: SelectionControlsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: SelectionControlsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('slider_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: SliderDemo()));
+      await tester.pumpWidget(const MaterialApp(home: SliderDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -441,14 +441,14 @@ void main() {
 
     testWidgets('tabs_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: TabsDemo()));
+      await tester.pumpWidget(const MaterialApp(home: TabsDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('tabs_fab_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: TabsFabDemo()));
+      await tester.pumpWidget(const MaterialApp(home: TabsFabDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -462,14 +462,14 @@ void main() {
 
     testWidgets('tooltip_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: TooltipDemo()));
+      await tester.pumpWidget(const MaterialApp(home: TooltipDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
 
     testWidgets('expansion_tile_list_demo', (WidgetTester tester) async {
       final SemanticsHandle handle = tester.ensureSemantics();
-      await tester.pumpWidget(MaterialApp(home: ExpansionTileListDemo()));
+      await tester.pumpWidget(const MaterialApp(home: ExpansionTileListDemo()));
       await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
       handle.dispose();
     });
@@ -493,7 +493,7 @@ void main() {
       testWidgets('backdrop_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: BackdropDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const BackdropDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -501,7 +501,7 @@ void main() {
       testWidgets('bottom_app_bar_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: BottomAppBarDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const BottomAppBarDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -509,7 +509,7 @@ void main() {
       testWidgets('bottom_navigation_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: BottomNavigationDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const BottomNavigationDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -517,7 +517,7 @@ void main() {
       testWidgets('buttons_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ButtonsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ButtonsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -525,7 +525,7 @@ void main() {
       testWidgets('cards_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: CardsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const CardsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -533,7 +533,7 @@ void main() {
       testWidgets('chip_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ChipDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ChipDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -541,7 +541,7 @@ void main() {
       testWidgets('data_table_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: DataTableDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const DataTableDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -549,7 +549,7 @@ void main() {
       testWidgets('date_and_time_picker_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: DateAndTimePickerDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const DateAndTimePickerDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -557,7 +557,7 @@ void main() {
       testWidgets('dialog_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: DialogDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const DialogDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       }, skip: theme == ThemeData.dark()); // Raised Button does not follow
@@ -567,7 +567,7 @@ void main() {
       testWidgets('drawer_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: DrawerDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const DrawerDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -575,7 +575,7 @@ void main() {
       testWidgets('elevation_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ElevationDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ElevationDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -583,7 +583,7 @@ void main() {
       testWidgets('expansion_panels_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ExpansionPanelsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ExpansionPanelsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -599,7 +599,7 @@ void main() {
       testWidgets('icons_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: IconsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const IconsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -632,7 +632,7 @@ void main() {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
         await tester.pumpWidget(
-          MaterialApp(theme: theme, home: ModalBottomSheetDemo())
+          MaterialApp(theme: theme, home: const ModalBottomSheetDemo())
         );
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
@@ -651,7 +651,7 @@ void main() {
       testWidgets('page_selector_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: PageSelectorDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const PageSelectorDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -660,7 +660,7 @@ void main() {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
         await tester.pumpWidget(
-          MaterialApp(theme: theme, home: PersistentBottomSheetDemo())
+          MaterialApp(theme: theme, home: const PersistentBottomSheetDemo())
         );
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
@@ -671,7 +671,7 @@ void main() {
       testWidgets('progress_indicator_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ProgressIndicatorDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ProgressIndicatorDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -687,7 +687,7 @@ void main() {
       testWidgets('scrollable_tabs_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ScrollableTabsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ScrollableTabsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -695,7 +695,7 @@ void main() {
       testWidgets('search_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: SearchDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const SearchDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -703,7 +703,7 @@ void main() {
       testWidgets('selection_controls_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: SelectionControlsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const SelectionControlsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -711,7 +711,7 @@ void main() {
       testWidgets('slider_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: SliderDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const SliderDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -731,7 +731,7 @@ void main() {
       testWidgets('tabs_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: TabsDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const TabsDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -739,7 +739,7 @@ void main() {
       testWidgets('tabs_fab_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: TabsFabDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const TabsFabDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -755,7 +755,7 @@ void main() {
       testWidgets('tooltip_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: TooltipDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const TooltipDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });
@@ -763,7 +763,7 @@ void main() {
       testWidgets('expansion_tile_list_demo $themeName', (WidgetTester tester) async {
         tester.binding.addTime(const Duration(seconds: 3));
         final SemanticsHandle handle = tester.ensureSemantics();
-        await tester.pumpWidget(MaterialApp(theme: theme, home: ExpansionTileListDemo()));
+        await tester.pumpWidget(MaterialApp(theme: theme, home: const ExpansionTileListDemo()));
         await expectLater(tester, meetsGuideline(textContrastGuideline));
         handle.dispose();
       });

dev/integration_tests/flutter_gallery/test/demo/material/chip_demo_test.dart

@@ -11,7 +11,7 @@ void main() {
     final SemanticsHandle handle = tester.ensureSemantics();
     await tester.pumpWidget(MaterialApp(
       theme: ThemeData(platform: TargetPlatform.iOS),
-      home: ChipDemo(),
+      home: const ChipDemo(),
     ));
 
     expect(tester.getSemantics(find.byIcon(Icons.vignette)), matchesSemantics(

dev/integration_tests/flutter_gallery/test/demo/material/drawer_demo_test.dart

@@ -10,7 +10,7 @@ void main() {
   testWidgets('Drawer header does not scroll', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       theme: ThemeData(platform: TargetPlatform.iOS),
-      home: DrawerDemo(),
+      home: const DrawerDemo(),
     ));
 
     await tester.tap(find.text('Tap here to open the drawer'));

dev/integration_tests/flutter_gallery/test/demo/material/expansion_panels_demo_test.dart

@@ -8,7 +8,7 @@ import 'package:flutter_test/flutter_test.dart';
 
 Future<void> main() async {
   testWidgets('Expansion panel demo: radio tile selection changes on tap', (WidgetTester tester) async {
-    await tester.pumpWidget(MaterialApp(home: ExpansionPanelsDemo()));
+    await tester.pumpWidget(const MaterialApp(home: ExpansionPanelsDemo()));
 
     expect(_expandIcons, findsNWidgets(3));
 

dev/integration_tests/hybrid_android_views/lib/main.dart

@@ -17,10 +17,12 @@ final List<PageWidget> _allPages = <PageWidget>[
 
 void main() {
   enableFlutterDriverExtension(handler: driverDataHandler.handleMessage);
-  runApp(MaterialApp(home: Home()));
+  runApp(const MaterialApp(home: Home()));
 }
 
 class Home extends StatelessWidget {
+  const Home({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

dev/integration_tests/hybrid_android_views/lib/motion_events_page.dart

@@ -17,16 +17,18 @@ import 'page.dart';
 const String kEventsFileName = 'touchEvents';
 
 class MotionEventsPage extends PageWidget {
-  const MotionEventsPage()
-      : super('Motion Event Tests', const ValueKey<String>('MotionEventsListTile'));
+  const MotionEventsPage({Key key})
+      : super('Motion Event Tests', const ValueKey<String>('MotionEventsListTile'), key: key);
 
   @override
   Widget build(BuildContext context) {
-    return MotionEventsBody();
+    return const MotionEventsBody();
   }
 }
 
 class MotionEventsBody extends StatefulWidget {
+  const MotionEventsBody({Key key}) : super(key: key);
+
   @override
   State createState() => MotionEventsBodyState();
 }
@@ -223,7 +225,7 @@ class MotionEventsBodyState extends State<MotionEventsBody> {
 }
 
 class TouchEventDiff extends StatelessWidget {
-  const TouchEventDiff(this.originalEvent, this.synthesizedEvent);
+  const TouchEventDiff(this.originalEvent, this.synthesizedEvent, {Key key}) : super(key: key);
 
   final Map<String, dynamic> originalEvent;
   final Map<String, dynamic> synthesizedEvent;

dev/integration_tests/hybrid_android_views/lib/nested_view_event_page.dart

@@ -12,14 +12,16 @@ import 'future_data_handler.dart';
 import 'page.dart';
 
 class NestedViewEventPage extends PageWidget {
-  const NestedViewEventPage()
-      : super('Nested View Event Tests', const ValueKey<String>('NestedViewEventTile'));
+  const NestedViewEventPage({Key key})
+      : super('Nested View Event Tests', const ValueKey<String>('NestedViewEventTile'), key: key);
 
   @override
-  Widget build(BuildContext context) => NestedViewEventBody();
+  Widget build(BuildContext context) => const NestedViewEventBody();
 }
 
 class NestedViewEventBody extends StatefulWidget {
+  const NestedViewEventBody({Key key}) : super(key: key);
+
   @override
   State<NestedViewEventBody> createState() => NestedViewEventBodyState();
 }

dev/integration_tests/hybrid_android_views/lib/page.dart

@@ -8,7 +8,7 @@ import 'package:flutter/material.dart';
 //
 /// A testing page has to override this in order to be put as one of the items in the main page.
 abstract class PageWidget extends StatelessWidget {
-  const PageWidget(this.title, this.tileKey);
+  const PageWidget(this.title, this.tileKey, {Key key}) : super(key: key);
 
   /// The title of the testing page
   ///

dev/integration_tests/ios_add2app_life_cycle/flutterapp/lib/main.dart

@@ -28,7 +28,7 @@ void main() {
 ///
 /// Rewiring semantics is a signal to native IOS test that the test has passed.
 class LifeCycleSpy extends StatefulWidget {
-  const LifeCycleSpy();
+  const LifeCycleSpy({Key key}) : super(key: key);
 
   @override
   _LifeCycleSpyState createState() => _LifeCycleSpyState();

dev/integration_tests/ios_app_with_extensions/lib/main.dart

@@ -4,9 +4,11 @@
 
 import 'package:flutter/material.dart';
 
-void main() => runApp(MyApp());
+void main() => runApp(const MyApp());
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   // This widget is the root of your application.
   @override
   Widget build(BuildContext context) {

dev/integration_tests/ios_platform_view_tests/lib/main.dart

@@ -7,11 +7,13 @@ import 'package:flutter_driver/driver_extension.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 /// The main app entrance of the test
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -50,7 +52,7 @@ class _MyHomePageState extends State<MyHomePage> {
             Navigator.push(
               context,
               MaterialPageRoute<PlatformViewPage>(
-                  builder: (BuildContext context) => PlatformViewPage()),
+                  builder: (BuildContext context) => const PlatformViewPage()),
             );
           },
         ),
@@ -67,7 +69,9 @@ class _MyHomePageState extends State<MyHomePage> {
 
 /// A page contains the platform view to be tested.
 class PlatformViewPage extends StatelessWidget {
-  final Key button = const ValueKey<String>('plus_button');
+  const PlatformViewPage({Key key}) : super(key: key);
+
+  static Key button = const ValueKey<String>('plus_button');
 
   @override
   Widget build(BuildContext context) {

dev/integration_tests/non_nullable/lib/main.dart

@@ -7,10 +7,12 @@ import 'package:flutter/material.dart';
 String? unused;
 
 void main() {
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(

dev/integration_tests/platform_interaction/lib/main.dart

@@ -12,10 +12,12 @@ import 'src/test_step.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(TestApp());
+  runApp(const TestApp());
 }
 
 class TestApp extends StatefulWidget {
+  const TestApp({Key key}) : super(key: key);
+
   @override
   _TestAppState createState() => _TestAppState();
 }

dev/integration_tests/ui/lib/driver.dart

@@ -7,10 +7,12 @@ import 'package:flutter_driver/driver_extension.dart';
 
 void main() {
   enableFlutterDriverExtension();
-  runApp(DriverTestApp());
+  runApp(const DriverTestApp());
 }
 
 class DriverTestApp extends StatefulWidget {
+  const DriverTestApp({Key key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() {
     return DriverTestAppState();

dev/integration_tests/ui/lib/empty.dart

@@ -8,10 +8,12 @@ import 'package:flutter_driver/driver_extension.dart';
 /// This application does nothing but show a empty screen.
 void main() {
   enableFlutterDriverExtension();
-  runApp(Empty());
+  runApp(const Empty());
 }
 
 class Empty extends StatelessWidget {
+  const Empty({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) => Container();
 }

dev/integration_tests/ui/lib/keyboard_resize.dart

@@ -12,21 +12,25 @@ void main() {
     // TODO(cbernaschina): remove when test flakiness is resolved
     return 'keyboard_resize';
   });
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       title: 'Text Editing',
       theme: ThemeData(primarySwatch: Colors.blue),
-      home: MyHomePage(),
+      home: const MyHomePage(),
     );
   }
 }
 
 class MyHomePage extends StatefulWidget {
+  const MyHomePage({Key key}) : super(key: key);
+
   @override
   _MyHomePageState createState() => _MyHomePageState();
 }

dev/integration_tests/ui/lib/keyboard_textfield.dart

@@ -10,21 +10,25 @@ import 'keys.dart' as keys;
 void main() {
   enableFlutterDriverExtension();
 
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       title: 'Keyboard & TextField',
       theme: ThemeData(primarySwatch: Colors.blue),
-      home: MyHomePage(),
+      home: const MyHomePage(),
     );
   }
 }
 
 class MyHomePage extends StatefulWidget {
+  const MyHomePage({Key key}) : super(key: key);
+
   @override
   _MyHomePageState createState() => _MyHomePageState();
 }

dev/integration_tests/ui/lib/license_check.dart

@@ -10,10 +10,12 @@ import 'package:flutter_driver/driver_extension.dart';
 /// license in it.
 void main() {
   enableFlutterDriverExtension();
-  runApp(ShowLicenses());
+  runApp(const ShowLicenses());
 }
 
 class ShowLicenses extends StatelessWidget {
+  const ShowLicenses({Key key}) : super(key: key);
+
   Widget _buildTestResultWidget(
     BuildContext context,
     AsyncSnapshot<List<LicenseEntry>> snapshot,

dev/integration_tests/ui/lib/screenshot.dart

@@ -12,10 +12,12 @@ import 'package:flutter_driver/driver_extension.dart';
 void main() {
   enableFlutterDriverExtension();
 
-  runApp(Toggler());
+  runApp(const Toggler());
 }
 
 class Toggler extends StatefulWidget {
+  const Toggler({Key key}) : super(key: key);
+
   @override
   State<Toggler> createState() => TogglerState();
 }

dev/integration_tests/web_e2e_tests/lib/text_editing_main.dart

@@ -4,9 +4,11 @@
 
 import 'package:flutter/material.dart';
 
-void main() => runApp(MyApp());
+void main() => runApp(const MyApp());
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const MaterialApp(

dev/manual_tests/lib/actions.dart

@@ -294,7 +294,7 @@ class UndoableDirectionalFocusAction extends UndoableFocusActionBase<Directional
 
 /// A button class that takes focus when clicked.
 class DemoButton extends StatefulWidget {
-  const DemoButton({this.name});
+  const DemoButton({Key key, this.name}) : super(key: key);
 
   final String name;
 

dev/manual_tests/lib/animated_icons.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class AnimatedIconsTestApp extends StatelessWidget {
+  const AnimatedIconsTestApp({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return const MaterialApp(
@@ -17,7 +19,7 @@ class AnimatedIconsTestApp extends StatelessWidget {
 }
 
 class IconsList extends StatelessWidget {
-  const IconsList();
+  const IconsList({Key key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -28,7 +30,7 @@ class IconsList extends StatelessWidget {
 }
 
 class IconSampleRow extends StatefulWidget {
-  const IconSampleRow(this.sample);
+  const IconSampleRow(this.sample, {Key key}) : super(key: key);
 
   final IconSample sample;
 
@@ -105,4 +107,4 @@ class IconSample {
   final String description;
 }
 
-void main() => runApp(AnimatedIconsTestApp());
+void main() => runApp(const AnimatedIconsTestApp());

dev/manual_tests/lib/card_collection.dart

@@ -18,6 +18,8 @@ class CardModel {
 }
 
 class CardCollection extends StatefulWidget {
+  const CardCollection({Key key}) : super(key: key);
+
   @override
   CardCollectionState createState() => CardCollectionState();
 }
@@ -389,7 +391,7 @@ class CardCollectionState extends State<CardCollection> {
 }
 
 void main() {
-  runApp(MaterialApp(
+  runApp(const MaterialApp(
     title: 'Cards',
     home: CardCollection(),
   ));

dev/manual_tests/lib/color_testing_demo.dart

@@ -10,10 +10,12 @@ class ColorTestingDemo extends StatelessWidget {
   static const String routeName = '/color_demo';
 
   @override
-  Widget build(BuildContext context) => ColorDemoHome();
+  Widget build(BuildContext context) => const ColorDemoHome();
 }
 
 class ColorDemoHome extends StatelessWidget {
+  const ColorDemoHome({Key key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -85,7 +87,7 @@ class ColorRow extends StatelessWidget {
 }
 
 void main() {
-  runApp(MaterialApp(
+  runApp(const MaterialApp(
     title: 'Color Testing Demo',
     home: ColorDemoHome(),
   ));

dev/manual_tests/lib/density.dart

@@ -19,9 +19,11 @@ final Map<int, Color> m2SwatchColors = <int, Color>{
 };
 final MaterialColor m2Swatch = MaterialColor(m2SwatchColors[500].value, m2SwatchColors);
 
-void main() => runApp(MyApp());
+void main() => runApp(const MyApp());
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key key}) : super(key: key);
+
   static const String _title = 'Density Test';
 
   @override
@@ -132,7 +134,7 @@ class LabeledCheckbox extends StatelessWidget {
 }
 
 class Options extends StatefulWidget {
-  const Options(this.model);
+  const Options(this.model, {Key key}) : super(key: key);
 
   final OptionModel model;
 

dev/manual_tests/lib/drag_and_drop.dart

@@ -7,6 +7,8 @@ import 'dart:math' as math;
 import 'package:flutter/material.dart';
 
 class ExampleDragTarget extends StatefulWidget {
+  const ExampleDragTarget({Key key}) : super(key: key);
+
   @override
   ExampleDragTargetState createState() => ExampleDragTargetState();
 }
@@ -174,7 +176,7 @@ class DashOutlineCirclePainter extends CustomPainter {
 }
 
 class MovableBall extends StatelessWidget {
-  const MovableBall(this.position, this.ballPosition, this.callback);
+  const MovableBall(this.position, this.ballPosition, this.callback, {Key key}) : super(key: key);
 
   final int position;
   final int ballPosition;
@@ -223,6 +225,8 @@ class MovableBall extends StatelessWidget {
 }
 
 class DragAndDropApp extends StatefulWidget {
+  const DragAndDropApp({Key key}) : super(key: key);
+
   @override
   DragAndDropAppState createState() => DragAndDropAppState();
 }
@@ -270,7 +274,7 @@ class DragAndDropAppState extends State<DragAndDropApp> {
           ),
           Expanded(
             child: Row(
-              children: <Widget>[
+              children: const <Widget>[
                 Expanded(child: ExampleDragTarget()),
                 Expanded(child: ExampleDragTarget()),
                 Expanded(child: ExampleDragTarget()),
@@ -295,7 +299,7 @@ class DragAndDropAppState extends State<DragAndDropApp> {
 }
 
 void main() {
-  runApp(MaterialApp(
+  runApp(const MaterialApp(
     title: 'Drag and Drop Flutter Demo',
     home: DragAndDropApp(),
   ));

dev/manual_tests/lib/focus.dart

@@ -13,7 +13,7 @@ void main() {
 }
 
 class DemoButton extends StatefulWidget {
-  const DemoButton({this.name, this.canRequestFocus = true, this.autofocus = false});
+  const DemoButton({Key key, this.name, this.canRequestFocus = true, this.autofocus = false}) : super(key: key);
 
   final String name;
   final bool canRequestFocus;

dev/manual_tests/lib/hover.dart

@@ -12,7 +12,7 @@ void main() {
 }
 
 class DemoButton extends StatelessWidget {
-  const DemoButton({this.name});
+  const DemoButton({Key key, this.name}) : super(key: key);
 
   final String name;
 

dev/manual_tests/lib/overlay_geometry.dart

@@ -86,6 +86,8 @@ class Marker extends StatelessWidget {
 }
 
 class OverlayGeometryApp extends StatefulWidget {
+  const OverlayGeometryApp({Key key}) : super(key: key);
+
   @override
   OverlayGeometryAppState createState() => OverlayGeometryAppState();
 }
@@ -209,6 +211,6 @@ void main() {
       accentColor: Colors.redAccent,
     ),
     title: 'Cards',
-    home: OverlayGeometryApp(),
+    home: const OverlayGeometryApp(),
   ));
 }

dev/manual_tests/lib/page_view.dart

@@ -14,6 +14,8 @@ class CardModel {
 }
 
 class PageViewApp extends StatefulWidget {
+  const PageViewApp({Key key}) : super(key: key);
+
   @override
   PageViewAppState createState() => PageViewAppState();
 }
@@ -146,6 +148,6 @@ void main() {
       primarySwatch: Colors.blue,
       accentColor: Colors.redAccent,
     ),
-    home: PageViewApp(),
+    home: const PageViewApp(),
   ));
 }

dev/manual_tests/test/overlay_geometry_test.dart

@@ -8,7 +8,7 @@ import 'package:manual_tests/overlay_geometry.dart' as overlay_geometry;
 
 void main() {
   testWidgets('Overlay geometry smoke test', (WidgetTester tester) async {
-    await tester.pumpWidget(MaterialApp(home: overlay_geometry.OverlayGeometryApp()));
+    await tester.pumpWidget(const MaterialApp(home: overlay_geometry.OverlayGeometryApp()));
     expect(find.byType(overlay_geometry.Marker), findsNothing);
     await tester.tap(find.text('Card 3'));
     await tester.pump();

examples/flutter_view/lib/main.dart

@@ -7,10 +7,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 void main() {
-  runApp(FlutterView());
+  runApp(const FlutterView());
 }
 
 class FlutterView extends StatelessWidget {
+  const FlutterView({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -18,12 +20,14 @@ class FlutterView extends StatelessWidget {
       theme: ThemeData(
         primarySwatch: Colors.grey,
       ),
-      home: MyHomePage(),
+      home: const MyHomePage(),
     );
   }
 }
 
 class MyHomePage extends StatefulWidget {
+  const MyHomePage({Key? key}) : super(key: key);
+
   @override
   _MyHomePageState createState() => _MyHomePageState();
 }

examples/image_list/lib/main.dart

@@ -124,7 +124,7 @@ const int IMAGES = 50;
 
 @immutable
 class MyApp extends StatelessWidget {
-  const MyApp(this.port);
+  const MyApp(this.port, {Key? key}) : super(key: key);
 
   final int port;
 

examples/layers/services/isolate.dart

@@ -197,6 +197,8 @@ class CalculationManager {
 // This is a StatefulWidget in order to hold the CalculationManager and
 // the AnimationController for the running animation.
 class IsolateExampleWidget extends StatefulWidget {
+  const IsolateExampleWidget({Key? key}) : super(key: key);
+
   @override
   IsolateExampleState createState() => IsolateExampleState();
 }
@@ -302,5 +304,5 @@ class IsolateExampleState extends State<StatefulWidget> with SingleTickerProvide
 }
 
 void main() {
-  runApp(MaterialApp(home: IsolateExampleWidget()));
+  runApp(const MaterialApp(home: IsolateExampleWidget()));
 }

examples/layers/test/gestures_test.dart

@@ -9,7 +9,7 @@ import '../widgets/gestures.dart';
 
 void main() {
   testWidgets('Tap on center change color', (WidgetTester tester) async {
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(const Directionality(
       textDirection: TextDirection.ltr,
       child: GestureDemo(),
     ));

examples/layers/test/sector_test.dart

@@ -13,6 +13,6 @@ void main() {
   });
 
   testWidgets('Sector Sixes', (WidgetTester tester) async {
-    await tester.pumpWidget(SectorApp());
+    await tester.pumpWidget(const SectorApp());
   });
 }

examples/layers/widgets/gestures.dart

@@ -55,6 +55,8 @@ class _GesturePainter extends CustomPainter {
 }
 
 class GestureDemo extends StatefulWidget {
+  const GestureDemo({Key? key}) : super(key: key);
+
   @override
   GestureDemoState createState() => GestureDemoState();
 }
@@ -223,7 +225,7 @@ void main() {
     theme: ThemeData.dark(),
     home: Scaffold(
       appBar: AppBar(title: const Text('Gestures Demo')),
-      body: GestureDemo(),
+      body: const GestureDemo(),
     ),
   ));
 }

examples/layers/widgets/sectors.dart

@@ -16,6 +16,8 @@ RenderBoxToRenderSectorAdapter initCircle() {
 }
 
 class SectorApp extends StatefulWidget {
+  const SectorApp({Key? key}) : super(key: key);
+
   @override
   SectorAppState createState() => SectorAppState();
 }
@@ -163,5 +165,5 @@ class SectorAppState extends State<SectorApp> {
 }
 
 void main() {
-  runApp(SectorApp());
+  runApp(const SectorApp());
 }

examples/layers/widgets/spinning_square.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/widgets.dart';
 
 class SpinningSquare extends StatefulWidget {
+  const SpinningSquare({Key? key}) : super(key: key);
+
   @override
   _SpinningSquareState createState() => _SpinningSquareState();
 }
@@ -44,5 +46,5 @@ class _SpinningSquareState extends State<SpinningSquare> with SingleTickerProvid
 }
 
 void main() {
-  runApp(Center(child: SpinningSquare()));
+  runApp(const Center(child: SpinningSquare()));
 }

examples/layers/widgets/styled_text.dart

@@ -58,6 +58,8 @@ Widget toStyledText(String name, String text) {
 Widget toPlainText(String name, String text) => Text(name + ':' + text);
 
 class SpeakerSeparator extends StatelessWidget {
+  const SpeakerSeparator({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -73,6 +75,8 @@ class SpeakerSeparator extends StatelessWidget {
 }
 
 class StyledTextDemo extends StatefulWidget {
+  const StyledTextDemo({Key? key}) : super(key: key);
+
   @override
   _StyledTextDemoState createState() => _StyledTextDemoState();
 }
@@ -99,7 +103,7 @@ class _StyledTextDemoState extends State<StyledTextDemo> {
             .map<Widget>((List<String> nameAndText) => _toText(nameAndText[0], nameAndText[1]))
             .expand((Widget line) => <Widget>[
               line,
-              SpeakerSeparator(),
+              const SpeakerSeparator(),
             ])
             .toList()..removeLast(),
         ),
@@ -117,7 +121,7 @@ void main() {
       ),
       body: Material(
         color: Colors.grey.shade50,
-        child: StyledTextDemo(),
+        child: const StyledTextDemo(),
       ),
     ),
   ));

examples/platform_channel/lib/main.dart

@@ -8,6 +8,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 class PlatformChannel extends StatefulWidget {
+  const PlatformChannel({Key? key}) : super(key: key);
+
   @override
   _PlatformChannelState createState() => _PlatformChannelState();
 }
@@ -80,5 +82,5 @@ class _PlatformChannelState extends State<PlatformChannel> {
 }
 
 void main() {
-  runApp(MaterialApp(home: PlatformChannel()));
+  runApp(const MaterialApp(home: PlatformChannel()));
 }

examples/platform_channel_swift/lib/main.dart

@@ -8,6 +8,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 class PlatformChannel extends StatefulWidget {
+  const PlatformChannel({Key? key}) : super(key: key);
+
   @override
   _PlatformChannelState createState() => _PlatformChannelState();
 }
@@ -80,5 +82,5 @@ class _PlatformChannelState extends State<PlatformChannel> {
 }
 
 void main() {
-  runApp(MaterialApp(home: PlatformChannel()));
+  runApp(const MaterialApp(home: PlatformChannel()));
 }

examples/platform_view/lib/main.dart

@@ -8,10 +8,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 void main() {
-  runApp(PlatformView());
+  runApp(const PlatformView());
 }
 
 class PlatformView extends StatelessWidget {
+  const PlatformView({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(

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

@@ -123,6 +123,7 @@ class NavigationRail extends StatefulWidget {
   ///
   /// Typically used within a [Row] that defines the [Scaffold.body] property.
   const NavigationRail({
+    Key? key,
     this.backgroundColor,
     this.extended = false,
     this.leading,
@@ -147,7 +148,8 @@ class NavigationRail extends StatefulWidget {
         assert(minExtendedWidth == null || minExtendedWidth > 0),
         assert((minWidth == null || minExtendedWidth == null) || minExtendedWidth >= minWidth),
         assert(extended != null),
-        assert(!extended || (labelType == null || labelType == NavigationRailLabelType.none));
+        assert(!extended || (labelType == null || labelType == NavigationRailLabelType.none)),
+        super(key: key);
 
   /// Sets the color of the Container that holds all of the [NavigationRail]'s
   /// contents.

packages/flutter/test/cupertino/page_test.dart

@@ -494,7 +494,7 @@ class RtlOverrideWidgetsLocalization implements WidgetsLocalizations {
 }
 
 class KeepsStateTestWidget extends StatefulWidget {
-  const KeepsStateTestWidget({this.navigatorKey});
+  const KeepsStateTestWidget({Key? key, this.navigatorKey}) : super(key: key);
 
   final Key? navigatorKey;
 

packages/flutter/test/material/page_test.dart

@@ -960,7 +960,7 @@ Widget buildNavigator({
 }
 
 class KeepsStateTestWidget extends StatefulWidget {
-  const KeepsStateTestWidget({this.navigatorKey});
+  const KeepsStateTestWidget({Key? key, this.navigatorKey}) : super(key: key);
 
   final Key? navigatorKey;
 

packages/flutter/test/material/tabs_test.dart

@@ -3308,7 +3308,7 @@ void main() {
   });
 
   testWidgets('Crash on dispose', (WidgetTester tester) async {
-    await tester.pumpWidget(Padding(padding: const EdgeInsets.only(right: 200.0), child: TabBarDemo()));
+    await tester.pumpWidget(const Padding(padding: EdgeInsets.only(right: 200.0), child: TabBarDemo()));
     await tester.tap(find.byIcon(Icons.directions_bike));
     // There was a time where this would throw an exception
     // because we tried to send a notification on dispose.
@@ -3428,6 +3428,8 @@ class _KeepAliveInkState extends State<KeepAliveInk> with AutomaticKeepAliveClie
 }
 
 class TabBarDemo extends StatelessWidget {
+  const TabBarDemo({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(

packages/flutter/test/widgets/framework_test.dart

@@ -1667,7 +1667,7 @@ class DependentState extends State<DependentStatefulWidget> {
 }
 
 class SwapKeyWidget extends StatefulWidget {
-  const SwapKeyWidget({this.childKey}): super();
+  const SwapKeyWidget({Key? key, this.childKey}): super(key: key);
 
   final Key? childKey;
   @override

packages/flutter/test/widgets/independent_widget_layout_test.dart

@@ -270,7 +270,7 @@ enum WidgetState {
 }
 
 class TestStates extends StatefulWidget {
-  const TestStates({required this.states});
+  const TestStates({Key? key, required this.states}) : super(key: key);
 
   final List<WidgetState> states;
 

packages/flutter/test/widgets/navigator_restoration_test.dart

@@ -1030,13 +1030,13 @@ Route<void> _routeBuilder(BuildContext context, Object? arguments) {
 Route<void> _routeFutureBuilder(BuildContext context, Object? arguments) {
   return MaterialPageRoute<void>(
     builder: (BuildContext context) {
-      return RouteFutureWidget();
+      return const RouteFutureWidget();
     },
   );
 }
 
 class PagedTestWidget extends StatelessWidget {
-  const PagedTestWidget({this.restorationId = 'app'});
+  const PagedTestWidget({Key? key, this.restorationId = 'app'}) : super(key: key);
 
   final String restorationId;
 
@@ -1044,7 +1044,7 @@ class PagedTestWidget extends StatelessWidget {
   Widget build(BuildContext context) {
     return RootRestorationScope(
       restorationId: restorationId,
-      child: Directionality(
+      child: const Directionality(
         textDirection: TextDirection.ltr,
         child: PagedTestNavigator(),
       ),
@@ -1053,6 +1053,8 @@ class PagedTestWidget extends StatelessWidget {
 }
 
 class PagedTestNavigator extends StatefulWidget {
+  const PagedTestNavigator({Key? key}) : super(key: key);
+
   @override
   State<PagedTestNavigator> createState() => PagedTestNavigatorState();
 }
@@ -1157,7 +1159,7 @@ class TestPage extends Page<void> {
 }
 
 class TestWidget extends StatelessWidget {
-  const TestWidget({this.restorationId = 'app'});
+  const TestWidget({Key? key, this.restorationId = 'app'}) : super(key: key);
 
   final String? restorationId;
 
@@ -1237,6 +1239,8 @@ class RouteWidgetState extends State<RouteWidget> with RestorationMixin {
 }
 
 class RouteFutureWidget extends StatefulWidget {
+  const RouteFutureWidget({Key? key}): super(key: key);
+
   @override
   State<RouteFutureWidget> createState() => RouteFutureWidgetState();
 }

packages/flutter/test/widgets/page_route_builder_test.dart

@@ -6,6 +6,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 class TestPage extends StatelessWidget {
+  const TestPage({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -13,12 +15,14 @@ class TestPage extends StatelessWidget {
       theme: ThemeData(
         primarySwatch: Colors.blue,
       ),
-      home: HomePage(),
+      home: const HomePage(),
     );
   }
 }
 
 class HomePage extends StatefulWidget {
+  const HomePage({Key? key}) : super(key: key);
+
   @override
   State<StatefulWidget> createState() => _HomePageState();
 }
@@ -30,7 +34,7 @@ class _HomePageState extends State<HomePage> {
       barrierColor: Colors.black54,
       opaque: false,
       pageBuilder: (BuildContext context, _, __) {
-        return ModalPage();
+        return const ModalPage();
       },
     ));
   }
@@ -50,6 +54,8 @@ class _HomePageState extends State<HomePage> {
 }
 
 class ModalPage extends StatelessWidget {
+  const ModalPage({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Material(
@@ -81,7 +87,7 @@ class ModalPage extends StatelessWidget {
 
 void main() {
   testWidgets('Barriers show when using PageRouteBuilder', (WidgetTester tester) async {
-    await tester.pumpWidget(TestPage());
+    await tester.pumpWidget(const TestPage());
     await tester.tap(find.byType(FloatingActionButton));
     await tester.pumpAndSettle();
     await expectLater(

packages/flutter/test/widgets/range_maintaining_scroll_physics_test.dart

@@ -7,7 +7,7 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 class ExpandingBox extends StatefulWidget {
-  const ExpandingBox({ required this.collapsedSize, required this.expandedSize });
+  const ExpandingBox({ Key? key, required this.collapsedSize, required this.expandedSize }) : super(key: key);
 
   final double collapsedSize;
   final double expandedSize;
@@ -220,12 +220,12 @@ void main() {
   });
 
   testWidgets('expanding page views', (WidgetTester tester) async {
-    await tester.pumpWidget(Padding(padding: const EdgeInsets.only(right: 200.0), child: TabBarDemo()));
+    await tester.pumpWidget(const Padding(padding: EdgeInsets.only(right: 200.0), child: TabBarDemo()));
     await tester.tap(find.text('bike'));
     await tester.pump();
     await tester.pump(const Duration(seconds: 1));
     final Rect bike1 = tester.getRect(find.byIcon(Icons.directions_bike));
-    await tester.pumpWidget(Padding(padding: EdgeInsets.zero, child: TabBarDemo()));
+    await tester.pumpWidget(const Padding(padding: EdgeInsets.zero, child: TabBarDemo()));
     final Rect bike2 = tester.getRect(find.byIcon(Icons.directions_bike));
     expect(bike2.center, bike1.shift(const Offset(100.0, 0.0)).center);
   });
@@ -266,6 +266,8 @@ void main() {
 }
 
 class TabBarDemo extends StatelessWidget {
+  const TabBarDemo({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(

packages/flutter/test/widgets/render_object_element_test.dart

@@ -28,7 +28,7 @@ class Pair<T> {
 /// and the other child in the bottom half. It will swap which child is on top
 /// and which is on bottom every time the widget is rendered.
 abstract class Swapper extends RenderObjectWidget {
-  const Swapper({ this.stable, this.swapper });
+  const Swapper({ Key? key, this.stable, this.swapper }) : super(key: key);
 
   final Widget? stable;
   final Widget? swapper;
@@ -42,9 +42,10 @@ abstract class Swapper extends RenderObjectWidget {
 
 class SwapperWithProperOverrides extends Swapper {
   const SwapperWithProperOverrides({
+    Key? key,
     Widget? stable,
     Widget? swapper,
-  }) : super(stable: stable, swapper: swapper);
+  }) : super(key: key, stable: stable, swapper: swapper);
 
   @override
   SwapperElement createElement() => SwapperElementWithProperOverrides(this);
@@ -52,9 +53,10 @@ class SwapperWithProperOverrides extends Swapper {
 
 class SwapperWithNoOverrides extends Swapper {
   const SwapperWithNoOverrides({
+    Key? key,
     Widget? stable,
     Widget? swapper,
-  }) : super(stable: stable, swapper: swapper);
+  }) : super(key: key, stable: stable, swapper: swapper);
 
   @override
   SwapperElement createElement() => SwapperElementWithNoOverrides(this);
@@ -62,9 +64,10 @@ class SwapperWithNoOverrides extends Swapper {
 
 class SwapperWithDeprecatedOverrides extends Swapper {
   const SwapperWithDeprecatedOverrides({
+    Key? key,
     Widget? stable,
     Widget? swapper,
-  }) : super(stable: stable, swapper: swapper);
+  }) : super(key: key, stable: stable, swapper: swapper);
 
   @override
   SwapperElement createElement() => SwapperElementWithDeprecatedOverrides(this);

packages/flutter/test/widgets/restoration_scopes_moving_test.dart

@@ -7,7 +7,7 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   testWidgets('widget moves scopes during restore', (WidgetTester tester) async {
-    await tester.pumpWidget(RootRestorationScope(
+    await tester.pumpWidget(const RootRestorationScope(
       restorationId: 'root',
       child: Directionality(
         textDirection: TextDirection.ltr,
@@ -111,6 +111,8 @@ void main() {
 }
 
 class TestWidgetWithCounterChild extends StatefulWidget {
+  const TestWidgetWithCounterChild({Key? key}) : super(key: key);
+
   @override
   State<TestWidgetWithCounterChild> createState() => TestWidgetWithCounterChildState();
 }
@@ -159,7 +161,7 @@ class TestWidgetWithCounterChildState extends State<TestWidgetWithCounterChild>
 }
 
 class Counter extends StatefulWidget {
-  const Counter({this.restorationId});
+  const Counter({Key? key, this.restorationId}) : super(key: key);
 
   final String? restorationId;
 
@@ -200,7 +202,7 @@ class CounterState extends State<Counter> with RestorationMixin {
 }
 
 class TestWidget extends StatefulWidget {
-  const TestWidget({required this.restorationId});
+  const TestWidget({Key? key, required this.restorationId}) : super(key: key);
 
   final String? restorationId;
 

packages/flutter/test/widgets/routes_test.dart

@@ -1658,7 +1658,7 @@ void main() {
 
     testWidgets('child with local history can be disposed', (WidgetTester tester) async {
       // Regression test: https://github.com/flutter/flutter/issues/52478
-      await tester.pumpWidget(MaterialApp(
+      await tester.pumpWidget(const MaterialApp(
         home: WidgetWithLocalHistory(),
       ));
 
@@ -1910,6 +1910,8 @@ class _TestDialogRouteWithCustomBarrierCurve<T> extends PopupRoute<T> {
 }
 
 class WidgetWithLocalHistory extends StatefulWidget {
+  const WidgetWithLocalHistory({Key? key}) : super(key: key);
+
   @override
   WidgetWithLocalHistoryState createState() => WidgetWithLocalHistoryState();
 }

packages/flutter/test/widgets/scroll_activity_test.dart

@@ -116,7 +116,7 @@ void main() {
 }
 
 class PageView62209 extends StatefulWidget {
-  const PageView62209();
+  const PageView62209({Key? key}) : super(key: key);
 
   @override
   _PageView62209State createState() => _PageView62209State();

packages/flutter_localizations/test/widgets_test.dart

@@ -169,7 +169,7 @@ Widget buildFrame({
 }
 
 class SyncLoadTest extends StatefulWidget {
-  const SyncLoadTest();
+  const SyncLoadTest({Key? key}) : super(key: key);
 
   @override
   SyncLoadTestState createState() => SyncLoadTestState();

packages/flutter_test/test/finders_test.dart

@@ -181,7 +181,7 @@ Widget _boilerplate(Widget child) {
 }
 
 class SimpleCustomSemanticsWidget extends LeafRenderObjectWidget {
-  const SimpleCustomSemanticsWidget(this.label);
+  const SimpleCustomSemanticsWidget(this.label, {Key? key}) : super(key: key);
 
   final String label;
 

packages/flutter_test/test/live_widget_controller_test.dart

@@ -8,6 +8,8 @@ import 'package:flutter/scheduler.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 class CountButton extends StatefulWidget {
+  const CountButton({Key? key}) : super(key: key);
+
   @override
   _CountButtonState createState() => _CountButtonState();
 }
@@ -28,6 +30,8 @@ class _CountButtonState extends State<CountButton> {
 }
 
 class AnimateSample extends StatefulWidget {
+  const AnimateSample({Key? key}) : super(key: key);
+
   @override
   _AnimateSampleState createState() => _AnimateSampleState();
 }
@@ -62,7 +66,7 @@ class _AnimateSampleState extends State<AnimateSample>
 
 void main() {
   test('Test pump on LiveWidgetController', () async {
-    runApp(MaterialApp(home: Center(child: CountButton())));
+    runApp(const MaterialApp(home: Center(child: CountButton())));
 
     await SchedulerBinding.instance!.endOfFrame;
     final WidgetController controller =
@@ -76,7 +80,7 @@ void main() {
   });
 
   test('Test pumpAndSettle on LiveWidgetController', () async {
-    runApp(MaterialApp(home: Center(child: AnimateSample())));
+    runApp(const MaterialApp(home: Center(child: AnimateSample())));
     await SchedulerBinding.instance!.endOfFrame;
     final WidgetController controller =
         LiveWidgetController(WidgetsBinding.instance!);

packages/integration_test/example/lib/my_app.dart

@@ -7,9 +7,11 @@ import 'package:flutter/material.dart';
 
 // ignore_for_file: public_member_api_docs
 
-void startApp() => runApp(MyApp());
+void startApp() => runApp(const MyApp());
 
 class MyApp extends StatefulWidget {
+  const MyApp({Key? key}) : super(key: key);
+
   @override
   _MyAppState createState() => _MyAppState();
 }

packages/integration_test/example/lib/my_web_app.dart

@@ -7,9 +7,11 @@ import 'package:flutter/material.dart';
 
 // ignore_for_file: public_member_api_docs
 
-void startApp() => runApp(MyWebApp());
+void startApp() => runApp(const MyWebApp());
 
 class MyWebApp extends StatefulWidget {
+  const MyWebApp({Key? key}) : super(key: key);
+
   @override
   _MyWebAppState createState() => _MyWebAppState();
 }