public async void GivenAJobApplicationService_WhenGetById_ThenRepoExecutesGetById() { //Given var testGuid = Guid.NewGuid(); var mockRepo = Substitute.For <JobApplicationRepository>(); var mockRepoFile = Substitute.For <FileRepository>(); mockRepo.GetById(testGuid) .Returns(Task.FromResult(new JobApplication(Guid.NewGuid(), Guid.NewGuid()))); var mockLogger = Substitute.For <ILoggerManager>(); var _jobApplcaitionService = new JobApplicationService(mockRepo, mockRepoFile, mockLogger); //When await _jobApplcaitionService.GetById(testGuid.ToString()); //Then await mockRepo.Received().GetById(testGuid); }