anchor.diff:        isA<AssertionError>().having(
           (source) => source.toString(),
           'toString',
  -        endsWith(
  +        contains(
               'InheritedProvider<int> used outside of MultiProvider must specify a child'),
         ),
       );
  
positive.code:       isA<AssertionError>().having(
          (source) => source.toString(),
          'toString',
          endsWith(
              'DeferredInheritedProvider<int, int> used outside of MultiProvider must specify a child'),
        ),
      );
  
negative.code:       isA<AssertionError>().having(
          (source) => source.toString(),
          'toString',
          contains(
              'DeferredInheritedProvider<int, int> used outside of MultiProvider must specify a child'),
        ),
      );
  