public void GivenCinemaShowWithoutAvailableSeats_WhenGetAvailableSeats_ShouldReturnNull() { // ARRANGE var cinemaShow = _fixture.Create <CinemaShowDTO>(); _cinemaShowRepositoryMock.Setup(r => r.GetCinemaShow(It.IsAny <string>())).Returns(cinemaShow); _seatRepositoryMock.Setup(s => s.GetAvailableSeats(cinemaShow.Id)).Returns(() => null); // ACT var seatService = new SeatService(_seatRepositoryMock.Object, _cinemaShowRepositoryMock.Object, _mapperMock.Object); var response = seatService.GetAvailableSeats(cinemaShow.Name); // ASSERT response.Should().BeNull(); }