anchor.diff:      this.locales = locales;
     }
   }
  +
  +class FakeSingletonWindow extends Fake implements SingletonFlutterWindow {
  +  SemanticsUpdate? lastUpdate;
  +
  +  @override
  +  PlatformDispatcher get platformDispatcher => PlatformDispatcher.instance;
  +
  +  @override
  +  void updateSemantics(SemanticsUpdate update) {
  +    lastUpdate = update;
  +  }
  +}
  
positive.code:     retrieveTestBinding(tester).window.localesTestValue = expectedValue;
      expect(observer.locales, equals(expectedValue));
      retrieveTestBinding(tester).window.localesTestValue = defaultLocales;
    });
  }
  
  
negative.code: // found in the LICENSE file.
  
  import 'dart:ui' as ui show window;
  import 'dart:ui' show AccessibilityFeatures, Brightness, Locale, PlatformDispatcher, SemanticsUpdate, SingletonFlutterWindow, Size, WindowPadding;
  
  import 'package:flutter/semantics.dart' show SemanticsUpdateBuilder;
  import 'package:flutter/widgets.dart' show WidgetsBinding, WidgetsBindingObserver;
  import 'package:flutter_test/flutter_test.dart';
  
  