anchor.diff:      if (_usesComponentFactory) {
         throw UnsupportedError('Use "addInjector" instead');
       }
  -    return fork(providers: _concat(_providers, providers));
  +    return fork(providers: [..._providers, ...providers]);
     }
   
     /// Returns a new instance of [NgTestBed] with the root injector wrapped.
  
positive.code:   /// Returns a new instance of [NgTestBed] with [stabilizers] added.
    NgTestBed<T> addStabilizers(Iterable<NgTestStabilizerFactory> stabilizers) {
      return fork(
        stabilizer: composeStabilizers([_createStabilizer]..addAll(stabilizers)),
      );
    }
  
  
negative.code: 
  /// Used to determine if there is an actively executing test.
  NgTestFixture<Object> activeTest;
  
  /// If any [NgTestFixture] is currently executing, calls `dispose` on it.
  ///
  