anchor.diff:  Widget buildTest({ double startToEndThreshold }) {
     Widget buildDismissableItem(int item) {
       return new Dismissable(
  -        key: new ValueKey<int>(item),
  -        direction: dismissDirection,
  -        onDismissed: (DismissDirection direction) {
  -          handleOnDismissed(direction, item);
  -        },
  -        onResize: () {
  -          handleOnResize(item);
  -        },
  -        background: background,
  -        dismissThresholds: startToEndThreshold == null
  -            ? <DismissDirection, double>{}
  -            : <DismissDirection, double>{DismissDirection.startToEnd: startToEndThreshold},
  -        child: new Container(
  -            width: itemExtent,
  -            height: itemExtent,
  -            child: new Text(item.toString())
  -        )
  +      key: new ValueKey<int>(item),
  +      direction: dismissDirection,
  +      onDismissed: (DismissDirection direction) {
  +        handleOnDismissed(direction, item);
  +      },
  +      onResize: () {
  +        handleOnResize(item);
  +      },
  +      background: background,
  +      dismissThresholds: startToEndThreshold == null
  +          ? <DismissDirection, double>{}
  +          : <DismissDirection, double>{DismissDirection.startToEnd: startToEndThreshold},
  +      child: new Container(
  +        width: itemExtent,
  +        height: itemExtent,
  +        child: new Text(item.toString())
  +      ),
       );
     }
   
     return new Container(
         padding: const EdgeInsets.all(10.0),
         child: new ScrollableList(
  -          scrollDirection: scrollDirection,
  -          itemExtent: itemExtent,
  -          children: <int>[0, 1, 2, 3, 4]
  -              .where((int i) => !dismissedItems.contains(i))
  -              .map(buildDismissableItem)
  +        scrollDirection: scrollDirection,
  +        itemExtent: itemExtent,
  +        children: <int>[0, 1, 2, 3, 4]
  +          .where((int i) => !dismissedItems.contains(i))
  +          .map(buildDismissableItem),
         )
     );
   }
  
positive.code:         child: new Column(
            children: <Widget>[
              new Test1215DismissableWidget('1'),
              new Test1215DismissableWidget('2')
            ]
          )
        )
      ));
      expect(find.text('1'), findsOneWidget);
      expect(find.text('2'), findsOneWidget);
  
negative.code:       key: new ObjectKey(text),
        child: new AspectRatio(
          aspectRatio: 1.0,
          child: new Text(this.text),
        ),
      );
    }
  }
  