anchor.diff:                slivers: <Widget>[
                   new CupertinoRefreshControl(
                     builder: null,
  -                  onRefresh: mockHelper.refreshTask,
  +                  onRefresh: onRefresh,
                     refreshIndicatorExtent: 0.0,
                   ),
                   buildAListOfStuff(),
  
positive.code:   );
  
    Future<void> refreshTask();
  }
negative.code:       await tester.pump(const Duration(seconds: 3));
  
        verifyInOrder(<void>[
          mockHelper.builder(
            typed(any),
            RefreshIndicatorMode.drag,
  