public void Exists_Should_ReturnTrueWhenExistAndFalseWhenDoesNot() { var db = new TFContext(DatabaseSimulator()); var genreServiceMock = new Mock <IGenreServices>(); var movieService = new MovieServices(db, genreServiceMock.Object); var movie = new Movie() { Id = 1, Title = "The Movie" }; bool doesNotExist = movieService.Exists(1); db.Movies.Add(movie); db.SaveChanges(); bool exist = movieService.Exists(1); Assert.IsFalse(doesNotExist); Assert.IsTrue(exist); }