widgets_test.dart 50 KB
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// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

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import 'dart:ui' as ui;

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import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
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import 'package:flutter_localizations/flutter_localizations.dart';
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class TestLocalizations {
  TestLocalizations(this.locale, this.prefix);

  final Locale locale;
  final String prefix;

  static Future<TestLocalizations> loadSync(Locale locale, String prefix) {
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    return SynchronousFuture<TestLocalizations>(TestLocalizations(locale, prefix));
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  }

  static Future<TestLocalizations> loadAsync(Locale locale, String prefix) {
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    return Future<TestLocalizations>.delayed(const Duration(milliseconds: 100))
      .then((_) => TestLocalizations(locale, prefix));
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  }

  static TestLocalizations of(BuildContext context) {
    return Localizations.of<TestLocalizations>(context, TestLocalizations);
  }

  String get message => '${prefix ?? ""}$locale';
}

class SyncTestLocalizationsDelegate extends LocalizationsDelegate<TestLocalizations> {
  SyncTestLocalizationsDelegate([this.prefix]);

  final String prefix; // Changing this value triggers a rebuild
  final List<bool> shouldReloadValues = <bool>[];

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  @override
  bool isSupported(Locale locale) => true;

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  @override
  Future<TestLocalizations> load(Locale locale) => TestLocalizations.loadSync(locale, prefix);

  @override
  bool shouldReload(SyncTestLocalizationsDelegate old) {
    shouldReloadValues.add(prefix != old.prefix);
    return prefix != old.prefix;
  }
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  @override
  String toString() => '$runtimeType($prefix)';
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}

class AsyncTestLocalizationsDelegate extends LocalizationsDelegate<TestLocalizations> {
  AsyncTestLocalizationsDelegate([this.prefix]);

  final String prefix; // Changing this value triggers a rebuild
  final List<bool> shouldReloadValues = <bool>[];

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  @override
  bool isSupported(Locale locale) => true;

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  @override
  Future<TestLocalizations> load(Locale locale) => TestLocalizations.loadAsync(locale, prefix);

  @override
  bool shouldReload(AsyncTestLocalizationsDelegate old) {
    shouldReloadValues.add(prefix != old.prefix);
    return prefix != old.prefix;
  }
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  @override
  String toString() => '$runtimeType($prefix)';
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}

class MoreLocalizations {
  MoreLocalizations(this.locale);

  final Locale locale;

  static Future<MoreLocalizations> loadSync(Locale locale) {
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    return SynchronousFuture<MoreLocalizations>(MoreLocalizations(locale));
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  }

  static Future<MoreLocalizations> loadAsync(Locale locale) {
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    return Future<MoreLocalizations>.delayed(const Duration(milliseconds: 100))
      .then((_) => MoreLocalizations(locale));
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  }

  static MoreLocalizations of(BuildContext context) {
    return Localizations.of<MoreLocalizations>(context, MoreLocalizations);
  }

  String get message => '$locale';
}

class SyncMoreLocalizationsDelegate extends LocalizationsDelegate<MoreLocalizations> {
  @override
  Future<MoreLocalizations> load(Locale locale) => MoreLocalizations.loadSync(locale);

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  @override
  bool isSupported(Locale locale) => true;

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  @override
  bool shouldReload(SyncMoreLocalizationsDelegate old) => false;
}

class AsyncMoreLocalizationsDelegate extends LocalizationsDelegate<MoreLocalizations> {
  @override
  Future<MoreLocalizations> load(Locale locale) => MoreLocalizations.loadAsync(locale);

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  @override
  bool isSupported(Locale locale) => true;

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  @override
  bool shouldReload(AsyncMoreLocalizationsDelegate old) => false;
}

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class OnlyRTLDefaultWidgetsLocalizations extends DefaultWidgetsLocalizations {
  @override
  TextDirection get textDirection => TextDirection.rtl;
}

class OnlyRTLDefaultWidgetsLocalizationsDelegate extends LocalizationsDelegate<WidgetsLocalizations> {
  const OnlyRTLDefaultWidgetsLocalizationsDelegate();

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  @override
  bool isSupported(Locale locale) => true;

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  @override
  Future<WidgetsLocalizations> load(Locale locale) {
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    return SynchronousFuture<WidgetsLocalizations>(OnlyRTLDefaultWidgetsLocalizations());
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  }

  @override
  bool shouldReload(OnlyRTLDefaultWidgetsLocalizationsDelegate old) => false;
}

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Widget buildFrame({
  Locale locale,
  Iterable<LocalizationsDelegate<dynamic>> delegates,
  WidgetBuilder buildContent,
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  LocaleResolutionCallback localeResolutionCallback,
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  List<Locale> supportedLocales = const <Locale>[
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    Locale('en', 'US'),
    Locale('en', 'GB'),
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  ],
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}) {
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  return WidgetsApp(
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    color: const Color(0xFFFFFFFF),
    locale: locale,
    localizationsDelegates: delegates,
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    localeResolutionCallback: localeResolutionCallback,
    supportedLocales: supportedLocales,
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    onGenerateRoute: (RouteSettings settings) {
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      return PageRouteBuilder<void>(
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        pageBuilder: (BuildContext context, Animation<double> _, Animation<double> __) {
          return buildContent(context);
        }
      );
    },
  );
}

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class SyncLoadTest extends StatefulWidget {
  const SyncLoadTest();

  @override
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  SyncLoadTestState createState() => SyncLoadTestState();
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}

class SyncLoadTestState extends State<SyncLoadTest> {
  @override
  Widget build(BuildContext context) {
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    return Text(
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      TestLocalizations.of(context).message,
      textDirection: TextDirection.rtl,
    );
  }
}

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void main() {
  testWidgets('Localizations.localeFor in a WidgetsApp with system locale', (WidgetTester tester) async {
    BuildContext pageContext;

    await tester.pumpWidget(
      buildFrame(
        buildContent: (BuildContext context) {
          pageContext = context;
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          return const Text('Hello World', textDirection: TextDirection.ltr);
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        }
      )
    );

    await tester.binding.setLocale('en', 'GB');
    await tester.pump();
    expect(Localizations.localeOf(pageContext), const Locale('en', 'GB'));

    await tester.binding.setLocale('en', 'US');
    await tester.pump();
    expect(Localizations.localeOf(pageContext), const Locale('en', 'US'));
  });

  testWidgets('Localizations.localeFor in a WidgetsApp with an explicit locale', (WidgetTester tester) async {
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    const Locale locale = Locale('en', 'US');
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    BuildContext pageContext;

    await tester.pumpWidget(
      buildFrame(
        locale: locale,
        buildContent: (BuildContext context) {
          pageContext = context;
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          return const Text('Hello World');
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        },
      )
    );

    expect(Localizations.localeOf(pageContext), locale);

    await tester.binding.setLocale('en', 'GB');
    await tester.pump();

    // The WidgetApp's explicit locale overrides the system's locale.
    expect(Localizations.localeOf(pageContext), locale);
  });

  testWidgets('Synchronously loaded localizations in a WidgetsApp', (WidgetTester tester) async {
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    final List<LocalizationsDelegate<dynamic>> delegates = <LocalizationsDelegate<dynamic>>[
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      SyncTestLocalizationsDelegate(),
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      DefaultWidgetsLocalizations.delegate,
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    ];

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    Future<void> pumpTest(Locale locale) async {
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      await tester.pumpWidget(Localizations(
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        locale: locale,
        delegates: delegates,
        child: const SyncLoadTest(),
      ));
    }
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    await pumpTest(const Locale('en', 'US'));
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    expect(find.text('en_US'), findsOneWidget);
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    await pumpTest(const Locale('en', 'GB'));
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    await tester.pump();
    expect(find.text('en_GB'), findsOneWidget);

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    await pumpTest(const Locale('en', 'US'));
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    await tester.pump();
    expect(find.text('en_US'), findsOneWidget);
  });

  testWidgets('Asynchronously loaded localizations in a WidgetsApp', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
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          AsyncTestLocalizationsDelegate(),
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        ],
        buildContent: (BuildContext context) {
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          return Text(TestLocalizations.of(context).message);
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        },
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      )
    );
    await tester.pump(const Duration(milliseconds: 50)); // TestLocalizations.loadAsync() takes 100ms
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    expect(find.text('en_US'), findsNothing); // TestLocalizations hasn't been loaded yet
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    await tester.pump(const Duration(milliseconds: 50)); // TestLocalizations.loadAsync() completes
    await tester.pumpAndSettle();
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    expect(find.text('en_US'), findsOneWidget); // default test locale is US english
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    await tester.binding.setLocale('en', 'GB');
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    await tester.pump(const Duration(milliseconds: 100));
    await tester.pumpAndSettle();
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    expect(find.text('en_GB'), findsOneWidget);
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    await tester.binding.setLocale('en', 'US');
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    await tester.pump(const Duration(milliseconds: 50));
    // TestLocalizations.loadAsync() hasn't completed yet so the old text
    // localization is still displayed
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    expect(find.text('en_GB'), findsOneWidget);
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    await tester.pump(const Duration(milliseconds: 50)); // finish the async load
    await tester.pumpAndSettle();
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    expect(find.text('en_US'), findsOneWidget);
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  });

  testWidgets('Localizations with multiple sync delegates', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
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          SyncTestLocalizationsDelegate(),
          SyncMoreLocalizationsDelegate(),
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Text('B: ${MoreLocalizations.of(context).message}'),
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            ],
          );
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        },
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      )
    );

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    // All localizations were loaded synchronously
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    expect(find.text('A: en_US'), findsOneWidget);
    expect(find.text('B: en_US'), findsOneWidget);
  });

  testWidgets('Localizations with multiple delegates', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
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          SyncTestLocalizationsDelegate(),
          AsyncMoreLocalizationsDelegate(), // No resources until this completes
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Text('B: ${MoreLocalizations.of(context).message}'),
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            ],
          );
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        },
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      )
    );

    await tester.pump(const Duration(milliseconds: 50));
    expect(find.text('A: en_US'), findsNothing); // MoreLocalizations.load() hasn't completed yet
    expect(find.text('B: en_US'), findsNothing);

    await tester.pump(const Duration(milliseconds: 50));
    await tester.pumpAndSettle();

    expect(find.text('A: en_US'), findsOneWidget);
    expect(find.text('B: en_US'), findsOneWidget);
  });

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  testWidgets('Multiple Localizations', (WidgetTester tester) async {
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    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
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          SyncTestLocalizationsDelegate(),
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Localizations(
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                locale: const Locale('en', 'GB'),
                delegates: <LocalizationsDelegate<dynamic>>[
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                  SyncTestLocalizationsDelegate(),
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                  DefaultWidgetsLocalizations.delegate,
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                ],
                // Create a new context within the en_GB Localization
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                child: Builder(
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                  builder: (BuildContext context) {
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                    return Text('B: ${TestLocalizations.of(context).message}');
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                  },
                ),
              ),
            ],
          );
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        },
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      )
    );

    expect(find.text('A: en_US'), findsOneWidget);
    expect(find.text('B: en_GB'), findsOneWidget);
  });

  // If both the locale and the length and type of a Localizations delegate list
  // stays the same BUT one of its delegate.shouldReload() methods returns true,
  // then the dependent widgets should rebuild.
  testWidgets('Localizations sync delegate shouldReload returns true', (WidgetTester tester) async {
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    final SyncTestLocalizationsDelegate originalDelegate = SyncTestLocalizationsDelegate();
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    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
          originalDelegate,
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          SyncMoreLocalizationsDelegate(),
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Text('B: ${MoreLocalizations.of(context).message}'),
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            ],
          );
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        },
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      )
    );

    await tester.pumpAndSettle();
    expect(find.text('A: en_US'), findsOneWidget);
    expect(find.text('B: en_US'), findsOneWidget);
    expect(originalDelegate.shouldReloadValues, <bool>[]);


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    final SyncTestLocalizationsDelegate modifiedDelegate = SyncTestLocalizationsDelegate('---');
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    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
          modifiedDelegate,
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          SyncMoreLocalizationsDelegate(),
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Text('B: ${MoreLocalizations.of(context).message}'),
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            ],
          );
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        },
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      )
    );

    await tester.pumpAndSettle();
    expect(find.text('A: ---en_US'), findsOneWidget);
    expect(find.text('B: en_US'), findsOneWidget);
    expect(modifiedDelegate.shouldReloadValues, <bool>[true]);
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    expect(originalDelegate.shouldReloadValues, <bool>[]);
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  });

  testWidgets('Localizations async delegate shouldReload returns true', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
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          AsyncTestLocalizationsDelegate(),
          AsyncMoreLocalizationsDelegate(),
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Text('B: ${MoreLocalizations.of(context).message}'),
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            ],
          );
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        },
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      )
    );

    await tester.pumpAndSettle();
    expect(find.text('A: en_US'), findsOneWidget);
    expect(find.text('B: en_US'), findsOneWidget);

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    final AsyncTestLocalizationsDelegate modifiedDelegate = AsyncTestLocalizationsDelegate('---');
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    await tester.pumpWidget(
      buildFrame(
        delegates: <LocalizationsDelegate<dynamic>>[
          modifiedDelegate,
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          AsyncMoreLocalizationsDelegate(),
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        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
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          return Column(
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            children: <Widget>[
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              Text('A: ${TestLocalizations.of(context).message}'),
              Text('B: ${MoreLocalizations.of(context).message}'),
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            ],
          );
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        },
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      )
    );

    await tester.pumpAndSettle();
    expect(find.text('A: ---en_US'), findsOneWidget);
    expect(find.text('B: en_US'), findsOneWidget);
    expect(modifiedDelegate.shouldReloadValues, <bool>[true]);
  });

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  testWidgets('Directionality tracks system locale', (WidgetTester tester) async {
    BuildContext pageContext;

    await tester.pumpWidget(
      buildFrame(
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        delegates: const <LocalizationsDelegate<dynamic>>[
          GlobalWidgetsLocalizations.delegate,
        ],
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        supportedLocales: const <Locale>[
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          Locale('en', 'GB'),
          Locale('ar', 'EG'),
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        ],
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        buildContent: (BuildContext context) {
          pageContext = context;
          return const Text('Hello World');
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        },
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      )
    );

    await tester.binding.setLocale('en', 'GB');
    await tester.pump();
    expect(Directionality.of(pageContext), TextDirection.ltr);

    await tester.binding.setLocale('ar', 'EG');
    await tester.pump();
    expect(Directionality.of(pageContext), TextDirection.rtl);
  });
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  testWidgets('localeResolutionCallback override', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        localeResolutionCallback: (Locale newLocale, Iterable<Locale> supportedLocales) {
          return const Locale('foo', 'BAR');
        },
        buildContent: (BuildContext context) {
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          return Text(Localizations.localeOf(context).toString());
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        },
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      )
    );

    await tester.pumpAndSettle();
    expect(find.text('foo_BAR'), findsOneWidget);

    await tester.binding.setLocale('en', 'GB');
    await tester.pumpAndSettle();
    expect(find.text('foo_BAR'), findsOneWidget);
  });


  testWidgets('supportedLocales and defaultLocaleChangeHandler', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
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          Locale('zh', 'CN'),
          Locale('en', 'GB'),
          Locale('en', 'CA'),
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        ],
        buildContent: (BuildContext context) {
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          return Text(Localizations.localeOf(context).toString());
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        },
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      )
    );

    await tester.pumpAndSettle();
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    expect(find.text('en_GB'), findsOneWidget);
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    // defaultLocaleChangedHandler prefers exact supported locale match
    await tester.binding.setLocale('en', 'CA');
    await tester.pumpAndSettle();
    expect(find.text('en_CA'), findsOneWidget);

    // defaultLocaleChangedHandler chooses 1st matching supported locale.languageCode
    await tester.binding.setLocale('en', 'US');
    await tester.pumpAndSettle();
    expect(find.text('en_GB'), findsOneWidget);

    // defaultLocaleChangedHandler: no matching supported locale, so use the 1st one
    await tester.binding.setLocale('da', 'DA');
    await tester.pumpAndSettle();
    expect(find.text('zh_CN'), findsOneWidget);
  });
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  testWidgets("Localizations.override widget tracks parent's locale and delegates", (WidgetTester tester) async {
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    await tester.pumpWidget(
      buildFrame(
        // Accept whatever locale we're given
        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
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        delegates: const <LocalizationsDelegate<dynamic>>[
          GlobalWidgetsLocalizations.delegate,
        ],
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        buildContent: (BuildContext context) {
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          return Localizations.override(
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            context: context,
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            child: Builder(
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              builder: (BuildContext context) {
                final Locale locale = Localizations.localeOf(context);
                final TextDirection direction = WidgetsLocalizations.of(context).textDirection;
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                return Text('$locale $direction');
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              },
            ),
          );
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        },
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      )
    );
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    // Initial WidgetTester locale is `en_US`.
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    await tester.pumpAndSettle();
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    expect(find.text('en_US TextDirection.ltr'), findsOneWidget);
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    await tester.binding.setLocale('en', 'CA');
    await tester.pumpAndSettle();
    expect(find.text('en_CA TextDirection.ltr'), findsOneWidget);

    await tester.binding.setLocale('ar', 'EG');
    await tester.pumpAndSettle();
    expect(find.text('ar_EG TextDirection.rtl'), findsOneWidget);

    await tester.binding.setLocale('da', 'DA');
    await tester.pumpAndSettle();
    expect(find.text('da_DA TextDirection.ltr'), findsOneWidget);
  });

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  testWidgets("Localizations.override widget overrides parent's DefaultWidgetLocalizations", (WidgetTester tester) async {
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    await tester.pumpWidget(
      buildFrame(
        // Accept whatever locale we're given
        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
        buildContent: (BuildContext context) {
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          return Localizations.override(
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            context: context,
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            delegates: const <OnlyRTLDefaultWidgetsLocalizationsDelegate>[
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              // Override: no matter what the locale, textDirection is always RTL.
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              OnlyRTLDefaultWidgetsLocalizationsDelegate(),
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            ],
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            child: Builder(
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              builder: (BuildContext context) {
                final Locale locale = Localizations.localeOf(context);
                final TextDirection direction = WidgetsLocalizations.of(context).textDirection;
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                return Text('$locale $direction');
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              },
            ),
          );
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        },
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      )
    );

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    // Initial WidgetTester locale is `en_US`.
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    await tester.pumpAndSettle();
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    expect(find.text('en_US TextDirection.rtl'), findsOneWidget);
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    await tester.binding.setLocale('en', 'CA');
    await tester.pumpAndSettle();
    expect(find.text('en_CA TextDirection.rtl'), findsOneWidget);

    await tester.binding.setLocale('ar', 'EG');
    await tester.pumpAndSettle();
    expect(find.text('ar_EG TextDirection.rtl'), findsOneWidget);

    await tester.binding.setLocale('da', 'DA');
    await tester.pumpAndSettle();
    expect(find.text('da_DA TextDirection.rtl'), findsOneWidget);
  });

  testWidgets('WidgetsApp overrides DefaultWidgetLocalizations', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        // Accept whatever locale we're given
        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
        delegates: <OnlyRTLDefaultWidgetsLocalizationsDelegate>[
          const OnlyRTLDefaultWidgetsLocalizationsDelegate(),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          final TextDirection direction = WidgetsLocalizations.of(context).textDirection;
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          return Text('$locale $direction');
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        },
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      )
    );

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    // Initial WidgetTester locale is `en_US`.
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    await tester.pumpAndSettle();
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    expect(find.text('en_US TextDirection.rtl'), findsOneWidget);
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    await tester.binding.setLocale('en', 'CA');
    await tester.pumpAndSettle();
    expect(find.text('en_CA TextDirection.rtl'), findsOneWidget);

    await tester.binding.setLocale('ar', 'EG');
    await tester.pumpAndSettle();
    expect(find.text('ar_EG TextDirection.rtl'), findsOneWidget);

    await tester.binding.setLocale('da', 'DA');
    await tester.pumpAndSettle();
    expect(find.text('da_DA TextDirection.rtl'), findsOneWidget);
  });
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  // We provide <Locale>[Locale('en', 'US'), Locale('zh', 'CN')] as ui.window.locales
  // for flutter tester so that the behavior of tests match that of production
  // environments. Here, we test the default locales.
  testWidgets('WidgetsApp DefaultWidgetLocalizations', (WidgetTester tester) async {
    await tester.pumpAndSettle();
    await tester.pumpWidget(
      buildFrame(
        // Accept whatever locale we're given
        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
        delegates: <OnlyRTLDefaultWidgetsLocalizationsDelegate>[
          const OnlyRTLDefaultWidgetsLocalizationsDelegate(),
        ],
        buildContent: (BuildContext context) {
          final Locale locale1 = ui.window.locales.first;
          final Locale locale2 = ui.window.locales[1];
          return Text('$locale1 $locale2');
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        },
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      )
    );
     // Initial WidgetTester default locales is `en_US` and `zh_CN`.
    await tester.pumpAndSettle();
    expect(find.text('en_US zh_CN'), findsOneWidget);
  });
698 699 700 701 702 703 704 705 706 707 708 709

  testWidgets('WidgetsApp.locale is resolved against supportedLocales', (WidgetTester tester) async {
    // app locale matches a supportedLocale
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('zh', 'CN'),
          Locale('en', 'US'),
        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
          return Text(Localizations.localeOf(context).toString());
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        },
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      )
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    // app locale matches a supportedLocale's language
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('zh', 'CN'),
          Locale('en', 'GB'),
        ],
        locale: const Locale('en', 'US'),
        buildContent: (BuildContext context) {
          return Text(Localizations.localeOf(context).toString());
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        },
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      )
    );
    await tester.pumpAndSettle();
    expect(find.text('en_GB'), findsOneWidget);

    // app locale matches no supportedLocale
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('zh', 'CN'),
          Locale('en', 'US'),
        ],
        locale: const Locale('ab', 'CD'),
        buildContent: (BuildContext context) {
          return Text(Localizations.localeOf(context).toString());
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        },
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      )
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_CN'), findsOneWidget);
  });
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  // Example from http://unicode.org/reports/tr35/#LanguageMatching
  testWidgets('WidgetsApp Unicode tr35 1', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('de'),
          Locale('fr'),
          Locale('ja'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'de', countryCode: 'AT'),
      Locale.fromSubtags(languageCode: 'fr'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('de'), findsOneWidget);
  });

  // Examples from http://unicode.org/reports/tr35/#LanguageMatching
  testWidgets('WidgetsApp Unicode tr35 2', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('ja', 'JP'),
          Locale('de'),
          Locale('zh', 'TW'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'de'),
      Locale.fromSubtags(languageCode: 'fr'),
      Locale.fromSubtags(languageCode: 'de', countryCode: 'SW'),
      Locale.fromSubtags(languageCode: 'it'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('de'), findsOneWidget);
  });

  testWidgets('WidgetsApp EdgeCase Chinese', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale.fromSubtags(languageCode: 'zh'),
          Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),
          Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'TW'),
          Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'HK'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'de'),
      Locale.fromSubtags(languageCode: 'fr'),
      Locale.fromSubtags(languageCode: 'de', countryCode: 'SW'),
      Locale.fromSubtags(languageCode: 'zh'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'HK'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'HK'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh'), findsOneWidget);

    // This behavior is up to the implementer to decide if a perfect scriptCode match
    // is better than a countryCode match.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'CN'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);


    // languageCode only match is not enough to prevent resolving a perfect match
    // further down the preferredLocales list.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'JP'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    // When no language match, we try for country only, since it is likely users are
    // at least familiar with their country's language. This is a possible case only
    // on iOS, where countryCode can be selected independently from language and script.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', scriptCode: 'Hans', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'HK'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);
  });

  // Same as 'WidgetsApp EdgeCase Chinese' test except the supportedLocales order is
  // reversed.
  testWidgets('WidgetsApp EdgeCase ReverseChinese', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'HK'),
          Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'TW'),
          Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),
          Locale.fromSubtags(languageCode: 'zh'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'de'),
      Locale.fromSubtags(languageCode: 'fr'),
      Locale.fromSubtags(languageCode: 'de', countryCode: 'SW'),
      Locale.fromSubtags(languageCode: 'zh'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'HK'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'HK'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);

    // This behavior is up to the implementer to decide if a perfect scriptCode match
    // is better than a countryCode match.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'CN'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);

    // languageCode only match is not enough to prevent resolving a perfect match
    // further down the preferredLocales list.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'JP'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'zh', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),
      Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hans_CN'), findsOneWidget);

    // When no language match, we try for country only, since it is likely users are
    // at least familiar with their country's language. This is a possible case only
    // on iOS, where countryCode can be selected independently from language and script.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', scriptCode: 'Hans', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'TW'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_TW'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'HK'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('zh_Hant_HK'), findsOneWidget);
  });

  // Examples from https://developer.android.com/guide/topics/resources/multilingual-support
  testWidgets('WidgetsApp Android', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('en'),
          Locale('de', 'DE'),
          Locale('es', 'ES'),
          Locale('fr', 'FR'),
          Locale('it', 'IT'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'fr', countryCode: 'CH'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('fr_FR'), findsOneWidget);
  });

  // Examples from https://developer.android.com/guide/topics/resources/multilingual-support
  testWidgets('WidgetsApp Android', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('en'),
          Locale('de', 'DE'),
          Locale('es', 'ES'),
          Locale('it', 'IT'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'fr', countryCode: 'CH'),
      Locale.fromSubtags(languageCode: 'it', countryCode: 'CH'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('it_IT'), findsOneWidget);
  });

  testWidgets('WidgetsApp Country-only fallback', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('en', 'US'),
          Locale('de', 'DE'),
          Locale('de', 'AU'),
          Locale('de', 'LU'),
          Locale('de', 'CH'),
          Locale('es', 'ES'),
          Locale('es', 'US'),
          Locale('it', 'IT'),
          Locale('zh', 'CN'),
          Locale('zh', 'TW'),
          Locale('fr', 'FR'),
          Locale('br', 'FR'),
          Locale('pt', 'BR'),
          Locale('pt', 'PT'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'CH'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('de_CH'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'FR'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('fr_FR'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'es', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('es_US'), findsOneWidget);

    // Strongly prefer matching first locale even if next one is perfect.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'pt'),
      Locale.fromSubtags(languageCode: 'pt', countryCode: 'PT'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('pt_PT'), findsOneWidget);

    // Don't country match with any other available match. This behavior is
    // up for reconsideration.
    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'BR'),
      Locale.fromSubtags(languageCode: 'pt'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('pt_BR'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'BR'),
      Locale.fromSubtags(languageCode: 'pt', countryCode: 'PT'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('pt_PT'), findsOneWidget);
  });

  // Simulates a Chinese-default app that supports english in Canada but not
  // French. French-Canadian users should get 'en_CA' instead of Chinese.
  testWidgets('WidgetsApp Multilingual country', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('zh', 'CN'),
          Locale('en', 'CA'),
          Locale('en', 'US'),
          Locale('en', 'AU'),
          Locale('de', 'DE'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
1220
        },
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      )
    );

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'fr', countryCode: 'CA'),
      Locale.fromSubtags(languageCode: 'fr'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_CA'), findsOneWidget);
  });


  testWidgets('WidgetsApp Common cases', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        // Decently well localized app.
        supportedLocales: const <Locale>[
          Locale('en', 'US'),
          Locale('en', 'GB'),
          Locale('en', 'AU'),
          Locale('en', 'CA'),
          Locale('zh', 'CN'),
          Locale('zh', 'TW'),
          Locale('de', 'DE'),
          Locale('de', 'CH'),
          Locale('es', 'MX'),
          Locale('es', 'ES'),
          Locale('es', 'AR'),
          Locale('es', 'CO'),
          Locale('ru', 'RU'),
          Locale('fr', 'FR'),
          Locale('fr', 'CA'),
          Locale('ar', 'SA'),
          Locale('ar', 'EG'),
          Locale('ar', 'IQ'),
          Locale('ar', 'MA'),
          Locale('af'),
          Locale('bg'),
          Locale('nl', 'NL'),
          Locale('pl'),
          Locale('cs'),
          Locale('fa'),
          Locale('el'),
          Locale('he'),
          Locale('hi'),
          Locale('pa'),
          Locale('ta'),
          Locale('id'),
          Locale('it', 'IT'),
          Locale('ja'),
          Locale('ko'),
          Locale('ms'),
          Locale('mn'),
          Locale('pt', 'BR'),
          Locale('pt', 'PT'),
          Locale('sv', 'SE'),
          Locale('th'),
          Locale('tr'),
          Locale('vi'),
        ],
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'CA'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_CA'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'AU'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_AU'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'CH'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('ar_SA'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('ar_SA'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ar', countryCode: 'IQ'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('ar_IQ'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'es', countryCode: 'ES'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('es_ES'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'es'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('es_MX'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'pa', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('pa'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'hi', countryCode: 'IN'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('hi'), findsOneWidget);

    // Multiple preferred locales:

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'NZ'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'AU'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'GB'),
      Locale.fromSubtags(languageCode: 'en'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_AU'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'ab'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'NZ'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'AU'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'GB'),
      Locale.fromSubtags(languageCode: 'en'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_AU'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'NZ'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'PH'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'ZA'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'CB'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'CA'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'AU'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'GB'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_CA'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'da'),
      Locale.fromSubtags(languageCode: 'en'),
      Locale.fromSubtags(languageCode: 'en', countryCode: 'CA'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_CA'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'da'),
      Locale.fromSubtags(languageCode: 'fo'),
      Locale.fromSubtags(languageCode: 'hr'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'da'),
      Locale.fromSubtags(languageCode: 'fo'),
      Locale.fromSubtags(languageCode: 'hr', countryCode: 'CA'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_CA'), findsOneWidget);
  });
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  testWidgets('WidgetsApp invalid preferredLocales', (WidgetTester tester) async {
    await tester.pumpWidget(
      buildFrame(
        supportedLocales: const <Locale>[
          Locale('zh', 'CN'),
          Locale('en', 'CA'),
          Locale('en', 'US'),
          Locale('en', 'AU'),
          Locale('de', 'DE'),
        ],
        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) {
          if (locale == null)
            return const Locale('und', 'US');
          return const Locale('en', 'US');
        },
        buildContent: (BuildContext context) {
          final Locale locale = Localizations.localeOf(context);
          return Text('$locale');
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        },
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      )
    );

    await tester.binding.setLocales(const <Locale>[
      Locale.fromSubtags(languageCode: 'en', countryCode: 'US'),]
    );
    await tester.pumpAndSettle();
    expect(find.text('en_US'), findsOneWidget);

    await tester.binding.setLocales(null);
    await tester.pumpAndSettle();
    expect(find.text('und_US'), findsOneWidget);

    await tester.binding.setLocales(const <Locale>[]);
    await tester.pumpAndSettle();
    expect(find.text('und_US'), findsOneWidget);
  });
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}