anchor.diff:      expect(value, isTrue);
     });
   
  -  testWidgets('State does not change if onValueChanged does not call setState()',
  -          (WidgetTester tester) async {
  +  testWidgets(
  +      'State does not change if onValueChanged does not call setState()',
  +      (WidgetTester tester) async {
       final Map<int, Widget> children = <int, Widget>{};
       children[0] = const Text('Child 1');
       children[1] = const Text('Child 2');
  
positive.code:   });
  
    testWidgets('Golden Test Placeholder Widget', (WidgetTester tester) async {
      final Map<int, Widget> children = <int, Widget>{};
      children[0] = new Container();
      children[1] = const Placeholder();
  
negative.code:       ),
      );
  
      final RenderBox buttonBox = tester
          .renderObject(find.byKey(const ValueKey<String>('Segmented Control')));
  
      // Default height of Placeholder is 400.0px, which is greater than heights
      // of other child widgets.
      expect(buttonBox.size.height, 400.0);
    });
  
    testWidgets('Width of each child widget is the same',
        (WidgetTester tester) async {
      final Map<int, Widget> children = <int, Widget>{};
      children[0] = new Container();
      children[1] = const Placeholder();
  