public void GetGenreNameWorksCorrectly() { var genres = new List <Genre>(); var mockGenreRepo = new Mock <IGenresRepository>(); mockGenreRepo.Setup(x => x.All()).Returns(genres.AsQueryable()); genres.Add(new Genre() { Id = "test123", Name = "ivan" }); var service = new GenresService(mockGenreRepo.Object); var result = service.GetGenreName("test123"); Assert.Equal("ivan", result); }