anchor.diff:      test('update data. (T13)', () {
         //when
         return ready
  -          .then((_) => months.add(new Map.from(january), 'John Doe'))
  -          .then((_) => months.add(new Map.from(february), 'John Doe'))
  -          .then((_) => months.add(new Map.from(march), 'John Doe'))
  -          .then((_) => months.add(new Map.from(april), 'John Doe'))
  -          .then((_) => months.add(new Map.from(june), 'John Doe'))
  -          .then((_) => months.add(new Map.from(july), 'John Doe'))
  -          .then((_) => months.add(new Map.from(august), 'John Doe'))
  -          .then((_) => months.add(new Map.from(september), 'John Doe'))
  -          .then((_) => months.add(new Map.from(october), 'John Doe'))
  -          .then((_) => months.add(new Map.from(november), 'John Doe'))
  -          .then((_) => months.add(new Map.from(december), 'John Doe'))
  +          .then((_) => months.addAll(clone(monthsCol), 'John Doe'))
             .then((_) => months.update({'days': 28}, {'days': 29, 'number': 2, 'name': 'February'}, 'John Doe'))
             .then((_) => months.data())
             .then((dataInfo) {
  -            expect(dataInfo['version'], equals(12));
  +            expect(dataInfo['version'], equals(13));
               var data = dataInfo['data'];
               expect(data[1], equals({'days': 29, 'number': 2, 'name': 'February', '_id': 'february'}));
               return dataInfo;
             })
  -          .then((_) => months.diffFromVersion(11))
  +          .then((_) => months.diffFromVersion(12))
             .then((dataDiff) {
               List diffList = dataDiff['diff'];
               expect(diffList.length, equals(1));
  
positive.code: 
      test('add data. (T02)', () {
        // when
        return ready.then((_) => months.add(new Map.from(january), 'John Doe'))
          .then((_) => months.data())
          .then((data){
  
  
negative.code: 
      test('change data with bad _id. (T06)', () {
        // given
        Future shouldThrow = ready.then((_) => months.add(clone(january), 'John Doe'))
  
        // when
          .then((_) => months.change('january', clone(february), 'Michael Smith'));
  
        // then
          expect(shouldThrow, throws);
  