public async Task GetAllAsyncWhenNoTutorsReturnsEmptyCollection() { // Arrange var mockUnitOfWork = GetDefaultUnitOfWorkRepositoryInstance(); var mockTutorRepository = GetDefaultTutorRepositoryInstance(); var mockExpertTopicRepository = new Mock <IExpertTopicRepository>(); mockTutorRepository.Setup(r => r.ListAsync()).ReturnsAsync(new List <Tutor>()); var service = new TutorService(mockTutorRepository.Object, mockUnitOfWork.Object, mockExpertTopicRepository.Object); // Act List <Tutor> result = (List <Tutor>) await service.ListAsync(); var TutorCount = result.Count; // Assert TutorCount.Should().Equals(0); }