anchor.diff:                slivers: <Widget>[
                   buildAListOfStuff(),
                   new CupertinoRefreshControl( // it's in the middle now.
  -                  builder: mockHelper.builder,
  -                  onRefresh: mockHelper.refreshTask,
  +                  builder: builder,
  +                  onRefresh: onRefresh,
                   ),
                   buildAListOfStuff(),
                 ],
  
positive.code:             child: new CustomScrollView(
                slivers: <Widget>[
                  new CupertinoRefreshControl(
                    builder: mockHelper.builder,
                    onRefresh: mockHelper.refreshTask,
                  ),
                  buildAListOfStuff(),
                ],
  
negative.code:         await tester.pump(const Duration(milliseconds: 50));
  
          verifyInOrder(<void>[
            mockHelper.builder(
              typed(any),
              RefreshIndicatorMode.armed,
  