public void ShouldNotifyListeners() { //Arrange var user1 = new User1(); var user2 = new User2(); videoCreator.RegisterListener(user1); videoCreator.RegisterListener(user2); //Act videoCreator.NewVideoAdd(new MyYoutubeChannel { Id = 4, VideoLink = "part4" }); //Assert user1.IsReceived.Should().BeTrue(); user2.IsReceived.Should().BeTrue(); }