public void CheckIfExistsWorks() { // Arrange var conversationRepo = new Mock <IRepository <Conversation> >(); conversationRepo.Setup(t => t.FindAll()).Returns(new List <Conversation> { new Conversation { Id = 1, Subject = "Conversation Test 1", IsDeleted = true } }.AsQueryable()); var conversationService = new ConversationService(agentService.Object, departmentService.Object, filterRepo.Object, filterExpressionFactory.Object, logRepo.Object); conversationService.Repository = conversationRepo.Object; // Act Action action = () => { conversationService.CheckIfExists(1); }; // Assert Assert.Throws <ExceptionWithCode>(action); }