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