Add debug check for localization parent (#20787)

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

@@ -109,6 +109,7 @@ class AboutListTile extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
+    assert(debugCheckHasMaterialLocalizations(context));
     return ListTile(
       leading: icon,
       title: child ??
@@ -263,6 +264,7 @@ class AboutDialog extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     final String name = applicationName ?? _defaultApplicationName(context);
     final String version = applicationVersion ?? _defaultApplicationVersion(context);
     final Widget icon = applicationIcon ?? _defaultApplicationIcon(context);
@@ -437,6 +439,7 @@ class _LicensePageState extends State<LicensePage> {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     final String name = widget.applicationName ?? _defaultApplicationName(context);
     final String version = widget.applicationVersion ?? _defaultApplicationVersion(context);
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);

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

@@ -11,6 +11,7 @@ import 'package:flutter/widgets.dart';
 
 import 'back_button.dart';
 import 'constants.dart';
+import 'debug.dart';
 import 'flexible_space_bar.dart';
 import 'icon_button.dart';
 import 'icons.dart';
@@ -332,6 +333,7 @@ class _AppBarState extends State<AppBar> {
   @override
   Widget build(BuildContext context) {
     assert(!widget.primary || debugCheckHasMediaQuery(context));
+    assert(debugCheckHasMaterialLocalizations(context));
     final ThemeData themeData = Theme.of(context);
     final ScaffoldState scaffold = Scaffold.of(context, nullOk: true);
     final ModalRoute<dynamic> parentRoute = ModalRoute.of(context);

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

@@ -4,6 +4,7 @@
 
 import 'package:flutter/widgets.dart';
 
+import 'debug.dart';
 import 'icon_button.dart';
 import 'icons.dart';
 import 'material_localizations.dart';
@@ -81,6 +82,7 @@ class BackButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     return IconButton(
       icon: const BackButtonIcon(),
       color: color,

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

@@ -10,6 +10,7 @@ import 'package:vector_math/vector_math_64.dart' show Vector3;
 
 import 'colors.dart';
 import 'constants.dart';
+import 'debug.dart';
 import 'ink_well.dart';
 import 'material.dart';
 import 'material_localizations.dart';
@@ -495,6 +496,7 @@ class _BottomNavigationBarState extends State<BottomNavigationBar> with TickerPr
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasDirectionality(context));
+    assert(debugCheckHasMaterialLocalizations(context));
 
     // Labels apply up to _bottomMargin padding. Remainder is media padding.
     final double additionalBottomPadding = math.max(MediaQuery.of(context).padding.bottom - _kBottomMargin, 0.0);

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

@@ -8,6 +8,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
 import 'colors.dart';
+import 'debug.dart';
 import 'material.dart';
 import 'material_localizations.dart';
 import 'scaffold.dart';
@@ -315,6 +316,7 @@ Future<T> showModalBottomSheet<T>({
 }) {
   assert(context != null);
   assert(builder != null);
+  assert(debugCheckHasMaterialLocalizations(context));
   return Navigator.push(context, _ModalBottomSheetRoute<T>(
     builder: builder,
     theme: Theme.of(context, shadowThemeOnly: true),

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

@@ -1429,6 +1429,7 @@ class _RawChipState extends State<RawChip> with TickerProviderStateMixin<RawChip
     assert(debugCheckHasMaterial(context));
     assert(debugCheckHasMediaQuery(context));
     assert(debugCheckHasDirectionality(context));
+    assert(debugCheckHasMaterialLocalizations(context));
 
     final ThemeData theme = Theme.of(context);
     final ChipThemeData chipTheme = ChipTheme.of(context);

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

@@ -945,6 +945,7 @@ class _DatePickerDialogState extends State<_DatePickerDialog> {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     final ThemeData theme = Theme.of(context);
     final Widget picker = Flexible(
       child: SizedBox(

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

@@ -5,6 +5,7 @@
 import 'package:flutter/widgets.dart';
 
 import 'material.dart';
+import 'material_localizations.dart';
 
 /// Asserts that the given context has a [Material] ancestor.
 ///
@@ -66,3 +67,63 @@ bool debugCheckHasMaterial(BuildContext context) {
   }());
   return true;
 }
+
+
+/// Asserts that the given context has a [Localizations] ancestor that contains
+/// a [MaterialLocalizations] delegate.
+///
+/// Used by many material design widgets to make sure that they are
+/// only used in contexts where they have access to localizations.
+///
+/// To call this function, use the following pattern, typically in the
+/// relevant Widget's build method:
+///
+/// ```dart
+/// assert(debugCheckHasMaterialLocalizations(context));
+/// ```
+///
+/// Does nothing if asserts are disabled. Always returns true.
+bool debugCheckHasMaterialLocalizations(BuildContext context) {
+  assert(() {
+    if (Localizations.of<MaterialLocalizations>(context, MaterialLocalizations) == null) {
+      final StringBuffer message = StringBuffer();
+      message.writeln('No MaterialLocalizations found.');
+      message.writeln(
+        '${context.widget.runtimeType} widgets require MaterialLocalizations '
+        'to be provided by a Localizations widget ancestor.'
+      );
+      message.writeln(
+        'Localizations are used to generate many different messages, labels,'
+        'and abbreviations which are used by the material library. '
+      );
+      message.writeln(
+        'To introduce a MaterialLocalizations, either use a '
+        ' MaterialApp at the root of your application to include them '
+        'automatically, or add a Localization widget with a '
+        'MaterialLocalizations delegate.'
+      );
+      message.writeln(
+        'The specific widget that could not find a MaterialLocalizations ancestor was:'
+      );
+      message.writeln('  ${context.widget}');
+      final List<Widget> ancestors = <Widget>[];
+      context.visitAncestorElements((Element element) {
+        ancestors.add(element.widget);
+        return true;
+      });
+      if (ancestors.isNotEmpty) {
+        message.write('The ancestors of this widget were:');
+        for (Widget ancestor in ancestors)
+          message.write('\n  $ancestor');
+      } else {
+        message.writeln(
+          'This widget is the root of the tree, so it has no '
+          'ancestors, let alone a "Localizations" ancestor.'
+        );
+      }
+      throw FlutterError(message.toString());
+    }
+    return true;
+  }());
+  return true;
+}

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

@@ -11,6 +11,7 @@ import 'package:flutter/widgets.dart';
 import 'button_bar.dart';
 import 'button_theme.dart';
 import 'colors.dart';
+import 'debug.dart';
 import 'ink_well.dart';
 import 'material.dart';
 import 'material_localizations.dart';
@@ -232,6 +233,7 @@ class AlertDialog extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     final List<Widget> children = <Widget>[];
     String label = semanticLabel;
 
@@ -490,6 +492,7 @@ class SimpleDialog extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     final List<Widget> body = <Widget>[];
     String label = semanticLabel;
 
@@ -596,6 +599,7 @@ Future<T> showDialog<T>({
   WidgetBuilder builder,
 }) {
   assert(child == null || builder == null);
+  assert(debugCheckHasMaterialLocalizations(context));
   return showGeneralDialog(
     context: context,
     pageBuilder: (BuildContext buildContext, Animation<double> animation, Animation<double> secondaryAnimation) {

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

@@ -6,6 +6,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
 import 'colors.dart';
+import 'debug.dart';
 import 'list_tile.dart';
 import 'material.dart';
 import 'material_localizations.dart';
@@ -116,6 +117,7 @@ class Drawer extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     String label = semanticLabel;
     switch (defaultTargetPlatform) {
       case TargetPlatform.iOS:
@@ -431,6 +433,7 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
   }
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     return ListTileTheme(
       style: ListTileStyle.drawer,
       child: _buildDrawer(context),

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

@@ -139,6 +139,7 @@ class _DropdownMenuState<T> extends State<_DropdownMenu<T>> {
     //
     // When the menu is dismissed we just fade the entire thing out
     // in the first 0.25s.
+    assert(debugCheckHasMaterialLocalizations(context));
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
     final _DropdownRoute<T> route = widget.route;
     final double unit = 0.5 / (route.items.length + 1.5);
@@ -631,6 +632,7 @@ class _DropdownButtonState<T> extends State<DropdownButton<T>> with WidgetsBindi
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
+    assert(debugCheckHasMaterialLocalizations(context));
 
     // The width of the button and the menu are defined by the widest
     // item and the width of the hint.

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

@@ -109,6 +109,7 @@ class _ExpandIconState extends State<ExpandIcon> with SingleTickerProviderStateM
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
+    assert(debugCheckHasMaterialLocalizations(context));
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
     final ThemeData theme = Theme.of(context);
     final String onTapHint = widget.isExpanded ? localizations.expandedIconTapHint : localizations.collapsedIconTapHint;

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

@@ -12,6 +12,7 @@ import 'button_theme.dart';
 import 'card.dart';
 import 'data_table.dart';
 import 'data_table_source.dart';
+import 'debug.dart';
 import 'dropdown.dart';
 import 'icon_button.dart';
 import 'icons.dart';
@@ -286,6 +287,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
   @override
   Widget build(BuildContext context) {
     // TODO(ianh): This whole build function doesn't handle RTL yet.
+    assert(debugCheckHasMaterialLocalizations(context));
     final ThemeData themeData = Theme.of(context);
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
     // HEADER

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

@@ -8,6 +8,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
 import 'constants.dart';
+import 'debug.dart';
 import 'divider.dart';
 import 'icon_button.dart';
 import 'icons.dart';
@@ -713,6 +714,7 @@ Future<T> showMenu<T>({
 }) {
   assert(context != null);
   assert(items != null && items.isNotEmpty);
+  assert(debugCheckHasMaterialLocalizations(context));
   String label = semanticLabel;
   switch (defaultTargetPlatform) {
     case TargetPlatform.iOS:
@@ -911,6 +913,7 @@ class _PopupMenuButtonState<T> extends State<PopupMenuButton<T>> {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     return widget.child != null
       ? InkWell(
           onTap: showButtonMenu,

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

@@ -7,6 +7,7 @@ import 'dart:math';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/rendering.dart';
 
+import 'debug.dart';
 import 'material.dart';
 import 'material_localizations.dart';
 
@@ -510,6 +511,7 @@ class _ReorderableListContentState extends State<_ReorderableListContent> with T
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     // We use the layout builder to constrain the cross-axis size of dragging child widgets.
     return LayoutBuilder(builder: (BuildContext context, BoxConstraints constraints) {
         final List<Widget> wrappedChildren = <Widget>[];

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

@@ -9,6 +9,7 @@ import 'package:flutter/widgets.dart';
 
 import 'app_bar.dart';
 import 'colors.dart';
+import 'debug.dart';
 import 'input_border.dart';
 import 'input_decorator.dart';
 import 'material_localizations.dart';
@@ -389,6 +390,7 @@ class _SearchPageState<T> extends State<_SearchPage<T>> {
 
   @override
   Widget build(BuildContext context) {
+    assert(debugCheckHasMaterialLocalizations(context));
     final ThemeData theme = widget.delegate.appBarTheme(context);
     final String searchFieldLabel = MaterialLocalizations.of(context).searchFieldLabel;
     Widget body;

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

@@ -540,6 +540,8 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
   Widget build(BuildContext context) {
     super.build(context); // See AutomaticKeepAliveClientMixin.
     assert(debugCheckHasMaterial(context));
+    // TODO(jonahwilliams): uncomment out this check once we have migrated tests.
+    // assert(debugCheckHasMaterialLocalizations(context));
     assert(debugCheckHasDirectionality(context));
     final ThemeData themeData = Theme.of(context);
     final TextStyle style = widget.style ?? themeData.textTheme.subhead;

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

@@ -79,6 +79,7 @@ class _AccountDetails extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasDirectionality(context));
+    assert(debugCheckHasMaterialLocalizations(context));
 
     final ThemeData theme = Theme.of(context);
     final List<Widget> children = <Widget>[];
@@ -308,6 +309,7 @@ class _UserAccountsDrawerHeaderState extends State<UserAccountsDrawerHeader> {
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
+    assert(debugCheckHasMaterialLocalizations(context));
     return Semantics(
       container: true,
       label: MaterialLocalizations.of(context).signedInLabel,

packages/flutter/test/material/app_bar_test.dart

@@ -845,7 +845,13 @@ void main() {
     const MediaQueryData topPadding100 = MediaQueryData(padding: EdgeInsets.only(top: 100.0));
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
+        locale: const Locale('en', 'US'),
+        delegates: const <LocalizationsDelegate<dynamic>>[
+          DefaultMaterialLocalizations.delegate,
+          DefaultWidgetsLocalizations.delegate,
+        ],
+        child: Directionality(
         textDirection: TextDirection.ltr,
         child: MediaQuery(
           data: topPadding100,
@@ -855,48 +861,66 @@ void main() {
           ),
         ),
       ),
-    );
+    ));
     expect(appBarTop(tester), 0.0);
     expect(appBarHeight(tester), kToolbarHeight);
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'US'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: topPadding100,
+          DefaultMaterialLocalizations.delegate,
-          child: Scaffold(
+          DefaultWidgetsLocalizations.delegate,
-            primary: true,
+        ],
-            appBar: AppBar(title: const Text('title'))
+        child: Directionality(
+          textDirection: TextDirection.ltr,
+          child: MediaQuery(
+            data: topPadding100,
+            child: Scaffold(
+              primary: true,
+              appBar: AppBar(title: const Text('title'))
           ),
         ),
       ),
-    );
+    ));
     expect(appBarTop(tester), 0.0);
     expect(tester.getTopLeft(find.text('title')).dy, greaterThan(100.0));
     expect(appBarHeight(tester), kToolbarHeight + 100.0);
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'US'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: topPadding100,
+          DefaultMaterialLocalizations.delegate,
-          child: Scaffold(
+          DefaultWidgetsLocalizations.delegate,
-            primary: false,
+        ],
-            appBar: AppBar(
+        child: Directionality(
-              bottom: PreferredSize(
+          textDirection: TextDirection.ltr,
-                preferredSize: const Size.fromHeight(200.0),
+          child: MediaQuery(
-                child: Container(),
+            data: topPadding100,
+            child: Scaffold(
+              primary: false,
+              appBar: AppBar(
+                bottom: PreferredSize(
+                  preferredSize: const Size.fromHeight(200.0),
+                  child: Container(),
               ),
             ),
           ),
         ),
       ),
-    );
+    ));
     expect(appBarTop(tester), 0.0);
     expect(appBarHeight(tester), kToolbarHeight + 200.0);
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
+        locale: const Locale('en', 'US'),
+        delegates: const <LocalizationsDelegate<dynamic>>[
+          DefaultMaterialLocalizations.delegate,
+          DefaultWidgetsLocalizations.delegate,
+        ],
+        child: Directionality(
         textDirection: TextDirection.ltr,
         child: MediaQuery(
           data: topPadding100,
@@ -911,18 +935,25 @@ void main() {
           ),
         ),
       ),
-    );
+    ));
     expect(appBarTop(tester), 0.0);
     expect(appBarHeight(tester), kToolbarHeight + 100.0 + 200.0);
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'US'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: topPadding100,
+          DefaultMaterialLocalizations.delegate,
-          child: AppBar(
+          DefaultWidgetsLocalizations.delegate,
-            primary: false,
+        ],
-            title: const Text('title'),
+        child: Directionality(
+          textDirection: TextDirection.ltr,
+          child: MediaQuery(
+            data: topPadding100,
+            child: AppBar(
+              primary: false,
+              title: const Text('title'),
+            ),
           ),
         ),
       ),
@@ -1095,7 +1126,13 @@ void main() {
     final Key trailingKey = UniqueKey();
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
+        locale: const Locale('en', 'US'),
+        delegates: const <LocalizationsDelegate<dynamic>>[
+          DefaultMaterialLocalizations.delegate,
+          DefaultWidgetsLocalizations.delegate,
+        ],
+        child: Directionality(
         textDirection: TextDirection.rtl,
         child: MediaQuery(
           data: topPadding100,
@@ -1109,7 +1146,7 @@ void main() {
           ),
         ),
       ),
-    );
+    ));
     expect(tester.getTopLeft(find.byType(AppBar)), const Offset(0.0, 0.0));
     expect(tester.getTopLeft(find.byKey(leadingKey)), const Offset(800.0 - 56.0, 100.0));
     expect(tester.getTopLeft(find.byKey(titleKey)), const Offset(416.0, 100.0));
@@ -1124,7 +1161,13 @@ void main() {
     final Key trailingKey = UniqueKey();
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
+        locale: const Locale('en', 'US'),
+        delegates: const <LocalizationsDelegate<dynamic>>[
+          DefaultMaterialLocalizations.delegate,
+          DefaultWidgetsLocalizations.delegate,
+        ],
+        child: Directionality(
         textDirection: TextDirection.rtl,
         child: MediaQuery(
           data: topPadding100,
@@ -1140,7 +1183,7 @@ void main() {
           ),
         ),
       ),
-    );
+    ));
     expect(tester.getTopLeft(find.byType(AppBar)), const Offset(0.0, 0.0));
     expect(tester.getTopLeft(find.byKey(leadingKey)), const Offset(800.0 - 56.0, 100.0));
     expect(tester.getTopLeft(find.byKey(titleKey)), const Offset(416.0, 100.0));
@@ -1155,7 +1198,13 @@ void main() {
     final Key trailingKey = UniqueKey();
 
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
+        locale: const Locale('en', 'US'),
+        delegates: const <LocalizationsDelegate<dynamic>>[
+          DefaultMaterialLocalizations.delegate,
+          DefaultWidgetsLocalizations.delegate,
+        ],
+        child: Directionality(
         textDirection: TextDirection.rtl,
         child: MediaQuery(
           data: topPadding100,
@@ -1171,7 +1220,7 @@ void main() {
           ),
         ),
       ),
-    );
+    ));
     expect(tester.getRect(find.byType(AppBar)), Rect.fromLTRB(0.0, 0.0, 800.00, 100.0 + 56.0));
     expect(tester.getRect(find.byKey(leadingKey)), Rect.fromLTRB(800.0 - 56.0, 100.0, 800.0, 100.0 + 56.0));
     expect(tester.getRect(find.byKey(trailingKey)), Rect.fromLTRB(0.0, 100.0, 400.0, 100.0 + 56.0));

packages/flutter/test/material/chip_theme_test.dart

@@ -64,7 +64,9 @@ void main() {
     bool value;
 
     Widget buildChip(ChipThemeData data) {
-      return Directionality(
+      return MaterialApp(
+        locale: const Locale('en', 'us'),
+        home: Directionality(
         textDirection: TextDirection.ltr,
         child: MediaQuery(
           data: MediaQueryData.fromWindow(window),
@@ -88,7 +90,7 @@ void main() {
             ),
           ),
         ),
-      );
+      ));
     }
 
     await tester.pumpWidget(buildChip(chipTheme));
@@ -111,7 +113,8 @@ void main() {
     );
     const bool value = false;
     Widget buildChip(ChipThemeData data) {
-      return Directionality(
+      return MaterialApp(
+        home: Directionality(
         textDirection: TextDirection.ltr,
         child: MediaQuery(
           data: MediaQueryData.fromWindow(window),
@@ -138,7 +141,7 @@ void main() {
             ),
           ),
         ),
-      );
+      ));
     }
 
     await tester.pumpWidget(buildChip(chipTheme));

packages/flutter/test/material/floating_action_button_location_test.dart

@@ -243,7 +243,13 @@ Widget buildFrame({
   EdgeInsets viewInsets = const EdgeInsets.only(bottom: 200.0),
   Widget bab,
 }) {
-  return Directionality(
+  return Localizations(
+    locale: const Locale('en', 'us'),
+    delegates: const <LocalizationsDelegate<dynamic>>[
+      DefaultWidgetsLocalizations.delegate,
+      DefaultMaterialLocalizations.delegate,
+    ],
+    child: Directionality(
     textDirection: textDirection,
     child: MediaQuery(
       data: MediaQueryData(viewInsets: viewInsets),
@@ -255,7 +261,7 @@ Widget buildFrame({
         body: listener,
       ),
     ),
-  );
+  ));
 }
 
 class _StartTopFloatingActionButtonLocation extends FloatingActionButtonLocation {

packages/flutter/test/material/scaffold_test.dart

@@ -12,9 +12,20 @@ import '../widgets/semantics_tester.dart';
 void main() {
   testWidgets('Scaffold control test', (WidgetTester tester) async {
     final Key bodyKey = UniqueKey();
-    await tester.pumpWidget(Directionality(
+    Widget boilerplate(Widget child) {
-      textDirection: TextDirection.ltr,
+      return Localizations(
-      child: Scaffold(
+        locale: const Locale('en', 'us'),
+        delegates: const <LocalizationsDelegate<dynamic>>[
+          DefaultWidgetsLocalizations.delegate,
+          DefaultMaterialLocalizations.delegate,
+        ],
+        child: Directionality(
+          textDirection: TextDirection.ltr,
+          child: child,
+        ),
+      );
+    }
+    await tester.pumpWidget(boilerplate(Scaffold(
         appBar: AppBar(title: const Text('Title')),
         body: Container(key: bodyKey),
       ),
@@ -30,9 +41,7 @@ void main() {
     RenderBox bodyBox = tester.renderObject(find.byKey(bodyKey));
     expect(bodyBox.size, equals(const Size(800.0, 544.0)));
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(boilerplate(MediaQuery(
-      textDirection: TextDirection.ltr,
-      child: MediaQuery(
         data: const MediaQueryData(viewInsets: EdgeInsets.only(bottom: 100.0)),
         child: Scaffold(
           appBar: AppBar(title: const Text('Title')),
@@ -44,17 +53,14 @@ void main() {
     bodyBox = tester.renderObject(find.byKey(bodyKey));
     expect(bodyBox.size, equals(const Size(800.0, 444.0)));
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(boilerplate(MediaQuery(
-      textDirection: TextDirection.ltr,
+      data: const MediaQueryData(viewInsets: EdgeInsets.only(bottom: 100.0)),
-      child: MediaQuery(
+      child: Scaffold(
-        data: const MediaQueryData(viewInsets: EdgeInsets.only(bottom: 100.0)),
+        appBar: AppBar(title: const Text('Title')),
-        child: Scaffold(
+        body: Container(key: bodyKey),
-          appBar: AppBar(title: const Text('Title')),
+        resizeToAvoidBottomPadding: false,
-          body: Container(key: bodyKey),
-          resizeToAvoidBottomPadding: false,
-        ),
       ),
-    ));
+    )));
 
     bodyBox = tester.renderObject(find.byKey(bodyKey));
     expect(bodyBox.size, equals(const Size(800.0, 544.0)));
@@ -62,24 +68,34 @@ void main() {
 
   testWidgets('Scaffold large bottom padding test', (WidgetTester tester) async {
     final Key bodyKey = UniqueKey();
-    await tester.pumpWidget(Directionality(
+
-      textDirection: TextDirection.ltr,
+    Widget boilerplate(Widget child) {
-      child: MediaQuery(
+      return Localizations(
-        data: const MediaQueryData(
+        locale: const Locale('en', 'us'),
-          viewInsets: EdgeInsets.only(bottom: 700.0),
+        delegates: const <LocalizationsDelegate<dynamic>>[
-        ),
+          DefaultWidgetsLocalizations.delegate,
-        child: Scaffold(
+          DefaultMaterialLocalizations.delegate,
-          body: Container(key: bodyKey),
+        ],
+        child: Directionality(
+          textDirection: TextDirection.ltr,
+          child: child,
         ),
+      );
+    }
+
+    await tester.pumpWidget(boilerplate(MediaQuery(
+      data: const MediaQueryData(
+        viewInsets: EdgeInsets.only(bottom: 700.0),
       ),
+      child: Scaffold(
+        body: Container(key: bodyKey),
+      ))
     ));
 
     final RenderBox bodyBox = tester.renderObject(find.byKey(bodyKey));
     expect(bodyBox.size, equals(const Size(800.0, 0.0)));
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(boilerplate(MediaQuery(
-      textDirection: TextDirection.ltr,
-      child: MediaQuery(
         data: const MediaQueryData(
           viewInsets: EdgeInsets.only(bottom: 500.0),
         ),
@@ -91,9 +107,7 @@ void main() {
 
     expect(bodyBox.size, equals(const Size(800.0, 100.0)));
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(boilerplate(MediaQuery(
-      textDirection: TextDirection.ltr,
-      child: MediaQuery(
         data: const MediaQueryData(
           viewInsets: EdgeInsets.only(bottom: 580.0),
         ),
@@ -597,64 +611,71 @@ void main() {
     final Key insideDrawer = UniqueKey();
     final Key insideBottomNavigationBar = UniqueKey();
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
-        textDirection: TextDirection.rtl,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(
+          DefaultWidgetsLocalizations.delegate,
-            padding: EdgeInsets.only(
+          DefaultMaterialLocalizations.delegate,
-              left: 20.0,
+        ],
-              top: 30.0,
+        child: Directionality(
-              right: 50.0,
+          textDirection: TextDirection.rtl,
-              bottom: 60.0,
+          child: MediaQuery(
+            data: const MediaQueryData(
+              padding: EdgeInsets.only(
+                left: 20.0,
+                top: 30.0,
+                right: 50.0,
+                bottom: 60.0,
+              ),
+              viewInsets: EdgeInsets.only(bottom: 200.0),
             ),
-            viewInsets: EdgeInsets.only(bottom: 200.0),
+            child: Scaffold(
-          ),
+              appBar: PreferredSize(
-          child: Scaffold(
+                preferredSize: const Size(11.0, 13.0),
-            appBar: PreferredSize(
+                child: Container(
-              preferredSize: const Size(11.0, 13.0),
+                  key: appBar,
-              child: Container(
+                  child: SafeArea(
-                key: appBar,
+                    child: Placeholder(key: insideAppBar),
-                child: SafeArea(
+                  ),
-                  child: Placeholder(key: insideAppBar),
                 ),
               ),
-            ),
+              body: Container(
-            body: Container(
+                key: body,
-              key: body,
-              child: SafeArea(
-                child: Placeholder(key: insideBody),
-              ),
-            ),
-            floatingActionButton: SizedBox(
-              key: floatingActionButton,
-              width: 77.0,
-              height: 77.0,
-              child: SafeArea(
-                child: Placeholder(key: insideFloatingActionButton),
-              ),
-            ),
-            persistentFooterButtons: <Widget>[
-              SizedBox(
-                key: persistentFooterButton,
-                width: 100.0,
-                height: 90.0,
                 child: SafeArea(
-                  child: Placeholder(key: insidePersistentFooterButton),
+                  child: Placeholder(key: insideBody),
                 ),
               ),
-            ],
+              floatingActionButton: SizedBox(
-            drawer: Container(
+                key: floatingActionButton,
-              key: drawer,
+                width: 77.0,
-              width: 204.0,
+                height: 77.0,
-              child: SafeArea(
+                child: SafeArea(
-                child: Placeholder(key: insideDrawer),
+                  child: Placeholder(key: insideFloatingActionButton),
+                ),
               ),
-            ),
+              persistentFooterButtons: <Widget>[
-            bottomNavigationBar: SizedBox(
+                SizedBox(
-              key: bottomNavigationBar,
+                  key: persistentFooterButton,
-              height: 85.0,
+                  width: 100.0,
-              child: SafeArea(
+                  height: 90.0,
-                child: Placeholder(key: insideBottomNavigationBar),
+                  child: SafeArea(
+                    child: Placeholder(key: insidePersistentFooterButton),
+                  ),
+                ),
+              ],
+              drawer: Container(
+                key: drawer,
+                width: 204.0,
+                child: SafeArea(
+                  child: Placeholder(key: insideDrawer),
+                ),
+              ),
+              bottomNavigationBar: SizedBox(
+                key: bottomNavigationBar,
+                height: 85.0,
+                child: SafeArea(
+                  child: Placeholder(key: insideBottomNavigationBar),
+                ),
               ),
             ),
           ),
@@ -692,57 +713,64 @@ void main() {
     final Key insidePersistentFooterButton = UniqueKey();
     final Key insideDrawer = UniqueKey();
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
-        textDirection: TextDirection.rtl,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(
+          DefaultWidgetsLocalizations.delegate,
-            padding: EdgeInsets.only(
+          DefaultMaterialLocalizations.delegate,
-              left: 20.0,
+        ],
-              top: 30.0,
+        child: Directionality(
-              right: 50.0,
+          textDirection: TextDirection.rtl,
-              bottom: 60.0,
+          child: MediaQuery(
+            data: const MediaQueryData(
+              padding: EdgeInsets.only(
+                left: 20.0,
+                top: 30.0,
+                right: 50.0,
+                bottom: 60.0,
+              ),
+              viewInsets: EdgeInsets.only(bottom: 200.0),
             ),
-            viewInsets: EdgeInsets.only(bottom: 200.0),
+            child: Scaffold(
-          ),
+              appBar: PreferredSize(
-          child: Scaffold(
+                preferredSize: const Size(11.0, 13.0),
-            appBar: PreferredSize(
+                child: Container(
-              preferredSize: const Size(11.0, 13.0),
+                  key: appBar,
-              child: Container(
+                  child: SafeArea(
-                key: appBar,
+                    child: Placeholder(key: insideAppBar),
-                child: SafeArea(
+                  ),
-                  child: Placeholder(key: insideAppBar),
                 ),
               ),
-            ),
+              body: Container(
-            body: Container(
+                key: body,
-              key: body,
-              child: SafeArea(
-                child: Placeholder(key: insideBody),
-              ),
-            ),
-            floatingActionButton: SizedBox(
-              key: floatingActionButton,
-              width: 77.0,
-              height: 77.0,
-              child: SafeArea(
-                child: Placeholder(key: insideFloatingActionButton),
-              ),
-            ),
-            persistentFooterButtons: <Widget>[
-              SizedBox(
-                key: persistentFooterButton,
-                width: 100.0,
-                height: 90.0,
                 child: SafeArea(
-                  child: Placeholder(key: insidePersistentFooterButton),
+                  child: Placeholder(key: insideBody),
                 ),
               ),
-            ],
+              floatingActionButton: SizedBox(
-            drawer: Container(
+                key: floatingActionButton,
-              key: drawer,
+                width: 77.0,
-              width: 204.0,
+                height: 77.0,
-              child: SafeArea(
+                child: SafeArea(
-                child: Placeholder(key: insideDrawer),
+                  child: Placeholder(key: insideFloatingActionButton),
+                ),
+              ),
+              persistentFooterButtons: <Widget>[
+                SizedBox(
+                  key: persistentFooterButton,
+                  width: 100.0,
+                  height: 90.0,
+                  child: SafeArea(
+                    child: Placeholder(key: insidePersistentFooterButton),
+                  ),
+                ),
+              ],
+              drawer: Container(
+                key: drawer,
+                width: 204.0,
+                child: SafeArea(
+                  child: Placeholder(key: insideDrawer),
+                ),
               ),
             ),
           ),

packages/flutter/test/widgets/nested_scroll_view_test.dart

@@ -318,19 +318,26 @@ void main() {
   testWidgets('NestedScrollViews with custom physics', (WidgetTester tester) async {
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
-      child: MediaQuery(
+      child: Localizations(
-        data: const MediaQueryData(),
+        locale: const Locale('en', 'US'),
-        child: NestedScrollView(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          physics: const _CustomPhysics(),
+          DefaultMaterialLocalizations.delegate,
-          headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
+          DefaultWidgetsLocalizations.delegate,
-            return <Widget>[
+        ],
-              const SliverAppBar(
+        child: MediaQuery(
-                floating: true,
+          data: const MediaQueryData(),
-                title: Text('AA'),
+          child: NestedScrollView(
-              ),
+            physics: const _CustomPhysics(),
-            ];
+            headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
-          },
+              return <Widget>[
-          body: Container(),
+                const SliverAppBar(
+                  floating: true,
+                  title: Text('AA'),
+                ),
+              ];
+            },
+            body: Container(),
+          ),
         ),
       ),
     ));

packages/flutter/test/widgets/scrollable_semantics_test.dart

@@ -105,27 +105,34 @@ void main() {
 
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
-      child: MediaQuery(
+      child: Localizations(
-      data: const MediaQueryData(),
+        locale: const Locale('en', 'us'),
-        child: Scrollable(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-        controller: scrollController,
+          DefaultWidgetsLocalizations.delegate,
-        viewportBuilder: (BuildContext context, ViewportOffset offset) {
+          DefaultMaterialLocalizations.delegate,
-          return Viewport(
+        ],
-            offset: offset,
+        child: MediaQuery(
-            slivers: <Widget>[
+          data: const MediaQueryData(),
-              const SliverAppBar(
+            child: Scrollable(
-                pinned: true,
+            controller: scrollController,
-                expandedHeight: kExpandedAppBarHeight,
+            viewportBuilder: (BuildContext context, ViewportOffset offset) {
-                flexibleSpace: FlexibleSpaceBar(
+              return Viewport(
-                  title: Text('App Bar'),
+                offset: offset,
-                ),
+                slivers: <Widget>[
-              ),
+                  const SliverAppBar(
-              SliverList(
+                    pinned: true,
-                delegate: SliverChildListDelegate(containers),
+                    expandedHeight: kExpandedAppBarHeight,
-              )
+                    flexibleSpace: FlexibleSpaceBar(
-            ],
+                      title: Text('App Bar'),
-          );
+                    ),
-        }),
+                  ),
+                  SliverList(
+                    delegate: SliverChildListDelegate(containers),
+                  )
+                ],
+              );
+            }),
+          ),
       ),
     ));
 
@@ -169,22 +176,29 @@ void main() {
       textDirection: TextDirection.ltr,
       child: MediaQuery(
         data: const MediaQueryData(),
-        child: Scrollable(
+        child: Localizations(
-          controller: scrollController,
+          locale: const Locale('en', 'us'),
-          viewportBuilder: (BuildContext context, ViewportOffset offset) {
+          delegates: const <LocalizationsDelegate<dynamic>>[
-            return Viewport(
+            DefaultWidgetsLocalizations.delegate,
-              offset: offset,
+            DefaultMaterialLocalizations.delegate,
-              slivers: <Widget>[
+          ],
-                const SliverAppBar(
+          child: Scrollable(
-                  pinned: true,
+            controller: scrollController,
-                  expandedHeight: kExpandedAppBarHeight,
+            viewportBuilder: (BuildContext context, ViewportOffset offset) {
-                  flexibleSpace: FlexibleSpaceBar(
+              return Viewport(
-                    title: Text('App Bar'),
+                offset: offset,
+                slivers: <Widget>[
+                  const SliverAppBar(
+                    pinned: true,
+                    expandedHeight: kExpandedAppBarHeight,
+                    flexibleSpace: FlexibleSpaceBar(
+                      title: Text('App Bar'),
+                    ),
                   ),
-                ),
+                ]..addAll(slivers),
-              ]..addAll(slivers),
+              );
-            );
+            },
-          },
+          ),
         ),
       ),
     ));

packages/flutter/test/widgets/sliver_semantics_test.dart

@@ -37,22 +37,29 @@ void _tests() {
     await tester.pumpWidget(
       Semantics(
         textDirection: TextDirection.ltr,
-        child: Directionality(
+        child: Localizations(
-          textDirection: TextDirection.ltr,
+          locale: const Locale('en', 'us'),
-          child: MediaQuery(
+          delegates: const <LocalizationsDelegate<dynamic>>[
-            data: const MediaQueryData(),
+            DefaultWidgetsLocalizations.delegate,
-            child: CustomScrollView(
+            DefaultMaterialLocalizations.delegate,
-              controller: scrollController,
+          ],
-              slivers: <Widget>[
+          child: Directionality(
-                const SliverAppBar(
+            textDirection: TextDirection.ltr,
-                  pinned: true,
+            child: MediaQuery(
-                  expandedHeight: appBarExpandedHeight,
+              data: const MediaQueryData(),
-                  title: Text('Semantics Test with Slivers'),
+              child: CustomScrollView(
-                ),
+                controller: scrollController,
-                SliverList(
+                slivers: <Widget>[
-                  delegate: SliverChildListDelegate(listChildren),
+                  const SliverAppBar(
-                ),
+                    pinned: true,
-              ],
+                    expandedHeight: appBarExpandedHeight,
+                    title: Text('Semantics Test with Slivers'),
+                  ),
+                   SliverList(
+                    delegate: SliverChildListDelegate(listChildren),
+                  ),
+                ],
+              ),
             ),
           ),
         ),
@@ -289,14 +296,21 @@ void _tests() {
     await tester.pumpWidget(
       Semantics(
         textDirection: TextDirection.ltr,
-        child: Directionality(
+        child: Localizations(
-          textDirection: TextDirection.ltr,
+          locale: const Locale('en', 'us'),
-          child: Center(
+          delegates: const <LocalizationsDelegate<dynamic>>[
-            child: SizedBox(
+            DefaultWidgetsLocalizations.delegate,
-              height: containerHeight,
+            DefaultMaterialLocalizations.delegate,
-              child: CustomScrollView(
+          ],
-                controller: scrollController,
+          child: Directionality(
-                slivers: slivers,
+            textDirection: TextDirection.ltr,
+            child: Center(
+              child: SizedBox(
+                height: containerHeight,
+                child: CustomScrollView(
+                  controller: scrollController,
+                  slivers: slivers,
+                ),
               ),
             ),
           ),
@@ -366,10 +380,17 @@ void _tests() {
     await tester.pumpWidget(
       Semantics(
         textDirection: TextDirection.ltr,
-        child: Directionality(
+        child: Localizations(
-          textDirection: TextDirection.ltr,
+          locale: const Locale('en', 'us'),
-          child: CustomScrollView(
+          delegates: const <LocalizationsDelegate<dynamic>>[
-            slivers: slivers,
+            DefaultWidgetsLocalizations.delegate,
+            DefaultMaterialLocalizations.delegate,
+          ],
+          child: Directionality(
+            textDirection: TextDirection.ltr,
+            child: CustomScrollView(
+              slivers: slivers,
+            ),
           ),
         ),
       ),
@@ -437,22 +458,29 @@ void _tests() {
     final ScrollController controller = ScrollController(initialScrollOffset: 280.0);
     await tester.pumpWidget(Semantics(
       textDirection: TextDirection.ltr,
-      child: Directionality(
+      child: Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(),
+          DefaultWidgetsLocalizations.delegate,
-          child: CustomScrollView(
+          DefaultMaterialLocalizations.delegate,
-            slivers: <Widget>[
+        ],
-              const SliverAppBar(
+        child: Directionality(
-                pinned: true,
+          textDirection: TextDirection.ltr,
-                expandedHeight: 100.0,
+          child: MediaQuery(
-                title: Text('AppBar'),
+            data: const MediaQueryData(),
-              ),
+            child: CustomScrollView(
-              SliverList(
+              slivers: <Widget>[
-                delegate: SliverChildListDelegate(listChildren),
+                const SliverAppBar(
-              ),
+                  pinned: true,
-            ],
+                  expandedHeight: 100.0,
-            controller: controller,
+                  title: Text('AppBar'),
+                ),
+                SliverList(
+                  delegate: SliverChildListDelegate(listChildren),
+                ),
+              ],
+              controller: controller,
+            ),
           ),
         ),
       ),
@@ -542,19 +570,26 @@ void _tests() {
     });
     await tester.pumpWidget(Semantics(
       textDirection: TextDirection.ltr,
-      child: Directionality(
+      child: Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(),
+          DefaultWidgetsLocalizations.delegate,
-          child: CustomScrollView(
+          DefaultMaterialLocalizations.delegate,
-            controller: controller,
+        ],
-            slivers: <Widget>[
+        child: Directionality(
-              const SliverAppBar(
+          textDirection: TextDirection.ltr,
-                pinned: true,
+          child: MediaQuery(
-                expandedHeight: 100.0,
+            data: const MediaQueryData(),
-                title: Text('AppBar'),
+            child: CustomScrollView(
-              ),
+              controller: controller,
-            ]..addAll(slivers),
+              slivers: <Widget>[
+                const SliverAppBar(
+                  pinned: true,
+                  expandedHeight: 100.0,
+                  title: Text('AppBar'),
+                ),
+              ]..addAll(slivers),
+            ),
           ),
         ),
       ),
@@ -642,23 +677,30 @@ void _tests() {
     final ScrollController controller = ScrollController(initialScrollOffset: 280.0);
     await tester.pumpWidget(Semantics(
       textDirection: TextDirection.ltr,
-      child: Directionality(
+      child: Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(),
+          DefaultWidgetsLocalizations.delegate,
-          child: CustomScrollView(
+          DefaultMaterialLocalizations.delegate,
-            reverse: true, // This is the important setting for this test.
+        ],
-            slivers: <Widget>[
+        child: Directionality(
-              const SliverAppBar(
+          textDirection: TextDirection.ltr,
-                pinned: true,
+          child: MediaQuery(
-                expandedHeight: 100.0,
+            data: const MediaQueryData(),
-                title: Text('AppBar'),
+            child: CustomScrollView(
-              ),
+              reverse: true, // This is the important setting for this test.
-              SliverList(
+              slivers: <Widget>[
-                delegate: SliverChildListDelegate(listChildren),
+                const SliverAppBar(
-              ),
+                  pinned: true,
-            ],
+                  expandedHeight: 100.0,
-            controller: controller,
+                  title: Text('AppBar'),
+                ),
+                SliverList(
+                  delegate: SliverChildListDelegate(listChildren),
+                ),
+              ],
+              controller: controller,
+            ),
           ),
         ),
       ),
@@ -748,20 +790,27 @@ void _tests() {
     });
     await tester.pumpWidget(Semantics(
       textDirection: TextDirection.ltr,
-      child: Directionality(
+      child: Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(),
+          DefaultWidgetsLocalizations.delegate,
-          child: CustomScrollView(
+          DefaultMaterialLocalizations.delegate,
-            reverse: true, // This is the important setting for this test.
+        ],
-            controller: controller,
+        child: Directionality(
-            slivers: <Widget>[
+          textDirection: TextDirection.ltr,
-              const SliverAppBar(
+          child: MediaQuery(
-                pinned: true,
+            data: const MediaQueryData(),
-                expandedHeight: 100.0,
+            child: CustomScrollView(
-                title: Text('AppBar'),
+              reverse: true, // This is the important setting for this test.
-              ),
+              controller: controller,
-            ]..addAll(slivers),
+              slivers: <Widget>[
+                const SliverAppBar(
+                  pinned: true,
+                  expandedHeight: 100.0,
+                  title: Text('AppBar'),
+                ),
+              ]..addAll(slivers),
+            ),
           ),
         ),
       ),
@@ -856,39 +905,46 @@ void _tests() {
       textDirection: TextDirection.ltr,
       child: Directionality(
         textDirection: TextDirection.ltr,
-        child: MediaQuery(
+        child: Localizations(
-          data: const MediaQueryData(),
+          locale: const Locale('en', 'us'),
-          child: Scrollable(
+          delegates: const <LocalizationsDelegate<dynamic>>[
-            controller: controller,
+            DefaultWidgetsLocalizations.delegate,
-            viewportBuilder: (BuildContext context, ViewportOffset offset) {
+            DefaultMaterialLocalizations.delegate,
-              return Viewport(
+          ],
-                offset: offset,
+          child: MediaQuery(
-                center: forwardAppBarKey,
+            data: const MediaQueryData(),
-                slivers: <Widget>[
+            child: Scrollable(
-                  SliverList(
+              controller: controller,
-                    delegate: SliverChildListDelegate(backwardChildren),
+              viewportBuilder: (BuildContext context, ViewportOffset offset) {
-                  ),
+                return Viewport(
-                  const SliverAppBar(
+                  offset: offset,
-                    pinned: true,
+                  center: forwardAppBarKey,
-                    expandedHeight: 100.0,
+                  slivers: <Widget>[
-                    flexibleSpace: FlexibleSpaceBar(
+                    SliverList(
-                      title: Text('Backward app bar', textDirection: TextDirection.ltr),
+                      delegate: SliverChildListDelegate(backwardChildren),
                     ),
-                  ),
+                    const SliverAppBar(
-                  SliverAppBar(
+                      pinned: true,
-                    pinned: true,
+                      expandedHeight: 100.0,
-                    key: forwardAppBarKey,
+                      flexibleSpace: FlexibleSpaceBar(
-                    expandedHeight: 100.0,
+                        title: Text('Backward app bar', textDirection: TextDirection.ltr),
-                    flexibleSpace: const FlexibleSpaceBar(
+                      ),
-                      title: Text('Forward app bar', textDirection: TextDirection.ltr),
                     ),
-                  ),
+                    SliverAppBar(
-                  SliverList(
+                      pinned: true,
-                    delegate: SliverChildListDelegate(forwardChildren),
+                      key: forwardAppBarKey,
-                  ),
+                      expandedHeight: 100.0,
-                ],
+                      flexibleSpace: const FlexibleSpaceBar(
-              );
+                        title: Text('Forward app bar', textDirection: TextDirection.ltr),
-            },
+                      ),
+                    ),
+                    SliverList(
+                      delegate: SliverChildListDelegate(forwardChildren),
+                    ),
+                  ],
+                );
+              },
+            ),
           ),
         ),
       ),

packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart

@@ -9,27 +9,34 @@ void main() {
   testWidgets('Sliver appbars - floating and pinned - second app bar stacks below', (WidgetTester tester) async {
     final ScrollController controller = ScrollController();
     await tester.pumpWidget(
-      Directionality(
+      Localizations(
-        textDirection: TextDirection.ltr,
+        locale: const Locale('en', 'us'),
-        child: MediaQuery(
+        delegates: const <LocalizationsDelegate<dynamic>>[
-          data: const MediaQueryData(),
+          DefaultWidgetsLocalizations.delegate,
-          child: CustomScrollView(
+          DefaultMaterialLocalizations.delegate,
-            controller: controller,
+        ],
-            slivers: const <Widget>[
+        child: Directionality(
-              SliverAppBar(floating: true, pinned: true, expandedHeight: 200.0, title: Text('A')),
+          textDirection: TextDirection.ltr,
-              SliverAppBar(primary: false, pinned: true, title: Text('B')),
+          child: MediaQuery(
-              SliverList(
+            data: const MediaQueryData(),
-                delegate: SliverChildListDelegate(
+            child: CustomScrollView(
-                  <Widget>[
+              controller: controller,
-                    Text('C'),
+              slivers: const <Widget>[
-                    Text('D'),
+                SliverAppBar(floating: true, pinned: true, expandedHeight: 200.0, title: Text('A')),
-                    SizedBox(height: 500.0),
+                SliverAppBar(primary: false, pinned: true, title: Text('B')),
-                    Text('E'),
+                SliverList(
-                    SizedBox(height: 500.0),
+                  delegate: SliverChildListDelegate(
-                  ],
+                    <Widget>[
+                      Text('C'),
+                      Text('D'),
+                      SizedBox(height: 500.0),
+                      Text('E'),
+                      SizedBox(height: 500.0),
+                    ],
+                  ),
                 ),
-              ),
+              ],
-            ],
+            ),
           ),
         ),
       ),