public void CallTopicsGetByIdOnce(int id) { // Arrange var topicServiceMock = new Mock <ITopicsService>(); var usersServiceMock = new Mock <IUsersService>(); var submissionsServiceMock = new Mock <ITopicSubmissionsService>(); var topicController = new TopicsController( topicServiceMock.Object, usersServiceMock.Object, submissionsServiceMock.Object); // Act topicController.Details(id); // Assert topicServiceMock.Verify(t => t.GetById(id), Times.Once); }