anchor.diff:      expect(finalView, orderedEquals([7,5,3,1]));
   
       collView.sorter = null;
  +    doChanges();
       validate();
       expect(finalView, orderedEquals([1,3,5,7]));
   
       collView.filter = null;
  +    doChanges();
       validate();
       expect(finalView, orderedEquals([1,2,3,4,5,6,7]));
     });
  
positive.code:     validate();
  
      collView.sorter = _sortDescending;
      validate();
      expect(finalView, orderedEquals([5,4,3,2,1]));
  
      collView.filter = _isOdd;
      validate();
      expect(finalView, orderedEquals([5,3,1]));
  
      collView.sorter = null;
      validate();
      expect(finalView, orderedEquals([1,3,5]));
  
      collView.filter = null;
      validate();
      expect(finalView, orderedEquals(_luggage));
    });
  
negative.code:     validate();
  
      collView.sorter = _sortEvenFirst;
      doChanges();
      validate();
      expect(finalView, orderedEquals([2,4,1,3,5]));
  
      collView.sorter = _sortOddFirst;
      doChanges();
      validate();
      expect(finalView, orderedEquals([1,3,5,2,4]));
  
      collView.sorter = null;
      doChanges();
      validate();
      expect(finalView, orderedEquals(_luggage));
    });
  