public void ShouldSaveTagsIntoDatabase() { //Arrange IUnitOfWork unitOfWork = Substitute.For <IUnitOfWork>(); LinkService linkService = new LinkService(unitOfWork); LinkDTO linkInfo = new LinkDTO { Link = "https://en.m.wikipedia.org/wiki/Medicine", IterationId = 1 }; //Act linkService.AddLinkToDB(linkInfo); //Assert unitOfWork.Links.Received(1).Add(Arg.Is <Link>(w => w.Url == "https://en.m.wikipedia.org/wiki/Medicine" && w.IterationId == 1)); }