anchor.diff:        );
       });
       final tiles = const <StaggeredTile>[
  -      const StaggeredTile.count(2,2),
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,2),
  -      const StaggeredTile.count(1,1),
  -
  -      const StaggeredTile.count(4,1),
  -
  -      const StaggeredTile.count(4,2),
  -
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,1),
  -
  -      const StaggeredTile.count(1,4),
  -      const StaggeredTile.count(1,3),
  -      const StaggeredTile.count(1,2),
  -      const StaggeredTile.count(1,1),
  -
  -      const StaggeredTile.count(1,1),
  -
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,1),
  -
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,1),
  -      const StaggeredTile.count(1,1),
  +      const StaggeredTile.count(2, 2),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 2),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(4, 1),
  +      const StaggeredTile.count(4, 2),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 4),
  +      const StaggeredTile.count(1, 3),
  +      const StaggeredTile.count(1, 2),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
  +      const StaggeredTile.count(1, 1),
       ];
   
  -    await tester.pumpWidget(
  -      new Directionality(
  -        textDirection : TextDirection.ltr,
  -        child: new StaggeredGridView.count(
  -            crossAxisSpacing: 0.0,
  -            mainAxisSpacing: 0.0,
  -            crossAxisCount: crossAxisCount,
  -            staggeredTiles: tiles,
  -            children: widgets,
  -        ),
  -      )
  -    );
  +    await tester.pumpWidget(new Directionality(
  +      textDirection: TextDirection.ltr,
  +      child: new StaggeredGridView.count(
  +        crossAxisSpacing: 0.0,
  +        mainAxisSpacing: 0.0,
  +        crossAxisCount: crossAxisCount,
  +        staggeredTiles: tiles,
  +        children: widgets,
  +      ),
  +    ));
   
       List<Offset> expectedTopLeftNormalizedOffsets = const <Offset>[
         const Offset(0.0, 0.0),
         const Offset(2.0, 0.0),
         const Offset(3.0, 0.0),
         const Offset(2.0, 1.0),
  -
         const Offset(0.0, 2.0),
  -
         const Offset(0.0, 3.0),
  -
         const Offset(0.0, 5.0),
         const Offset(1.0, 5.0),
         const Offset(2.0, 5.0),
         const Offset(3.0, 5.0),
  -
         const Offset(0.0, 6.0),
         const Offset(1.0, 6.0),
         const Offset(2.0, 6.0),
         const Offset(3.0, 6.0),
  -
         const Offset(3.0, 7.0),
         const Offset(2.0, 8.0),
         const Offset(3.0, 8.0),
  
positive.code:     await tester.pump();
  
      for (var item in log) {
        expect(tester.getTopLeft(find.text('$item')), equals
          (expectedTopLeftNormalizedOffsets[item] * cellLength  - const Offset
          (0.0, 1000.0)));
        expect(tester.getSize(find.text('$item')), equals(_getTileSize
          (tiles[item],
            cellLength)));
      }
  
      expect(log, equals(<int>[
        6, 7, 8, 9,
        10, 11, 12, 13,
        14, 15, 16
      ]));
      log.clear();
  
    });
  }
  
negative.code:     ];
  
      for (var item in log) {
        expect(tester.getTopLeft(find.text('$item')),
            equals(expectedTopLeftNormalizedOffsets[item] * cellLength));
        expect(tester.getSize(find.text('$item')),
            equals(_getTileSize(tiles[item], cellLength)));
      }
  
      expect(
          log,
          equals(<int>[
            0,
            1,
            2,
            3,
            4,
            5,
          ]));
      log.clear();
  
      final ScrollableState scrollableState =
          tester.state(find.byType(Scrollable));
      final ScrollPosition scrollPosition = scrollableState.position;
      scrollPosition.jumpTo(1000.0);
  
  