public async void GetByGenreAsync(string idGenre, int PageSize, int PageNumber) { IEnumerable <Track> track = new List <Track> (); _trackRepositoryMock.Setup(r => r.GetByGenreAsync(idGenre, PageSize, PageNumber)).Returns(Task.FromResult(track)); var result = await _trackService.GetByGenreAsync(idGenre, PageSize, PageNumber); Assert.NotNull(result); _trackRepositoryMock.Verify(x => x.GetByGenreAsync(idGenre, PageSize, PageNumber), Times.Once()); }