anchor.diff:      expect(elementA.name, 'a');
       expect(elementB.name, 'b');
       // unit.types
  -    expect(unitElement.topLevelVariables,
  -        unorderedEquals([elementA.variable, elementB.variable]));
  -    expect(unitElement.accessors, unorderedEquals([elementA, elementB]));
  +    expect(
  +        unitElement.topLevelVariables, [elementA.variable, elementB.variable]);
  +    expect(unitElement.accessors, [elementA, elementB]);
     }
   
     test_unitMembers_class_add() {
  
positive.code:     expect(elementD.name, 'd');
      // unit.types
      expect(unitElement.topLevelVariables,
          unorderedEquals([elementA, elementB, elementC, elementD]));
      expect(
          unitElement.accessors,
          unorderedEquals([
            elementA.getter,
            elementA.setter,
            elementB.getter,
            elementB.setter,
            elementC.getter,
            elementC.setter,
            elementD.getter,
            elementD.setter
          ]));
    }
  
    test_unitMembers_topLevelVariable_final() {
  
negative.code:     expect(newElementA.name, 'aaa2');
      expect(elementB, isNotNull);
      expect(elementB.name, 'bbb');
      expect(helper.element.methods, [newElementA, elementB]);
      // verify delta
      expect(helper.delta.addedConstructors, isEmpty);
      expect(helper.delta.removedConstructors, isEmpty);
  