public void GetElement_InputExistingId_TopicReturned() { int?TopicId = 2; var mock = new Mock <IUnitOfWork>(); mock.Setup(a => a.Topics.GetElement(TopicId.Value)).Returns(new Topic()); var service = new TopicService(mock.Object); var result = service.GetElement(TopicId.Value) as TopicDTO; Assert.IsNotNull(result); }