anchor.diff:  
       test('deprecatedChange data with bad _id. (T12)', () {
         // given
  -      Future shouldThrow = ready.then((_) => months.add(new Map.from(january), 'John Doe'))
  -
  -      // when
  -        .then((_) => months.deprecatedChange('january', new Map.from(february), 'Michael Smith'));
  +      Future shouldThrow = ready.then((_) => months.add(clone(january), 'John Doe'))
  +
  +      // when
  +        .then((_) => months.deprecatedChange('january', clone(february), 'Michael Smith'));
   
         // then
           expect(shouldThrow, throws);
  
positive.code: 
      test('deprecatedChange not existing data. (T11)', () {
        // when
        Future shouldThrow =  ready.then((_) => months.deprecatedChange('january', new Map.from(january), 'Michael Smith'));
  
        //then
          expect(shouldThrow, throws);
  
negative.code:           expect(diff['action'], equals('change'));
            expect(diff['_id'], equals('january'));
            Map strippedData = diff['data'];
            var res = clone(january)..addAll(january2);
            expect(strippedData, equals(res));
            expect(diff['author'], equals('Michael Smith'));
          });
  