public void Create_ShouldReturnInvalidModelState() { mockContext = new Mock <IHotelAC>(); mockSet = new Mock <DbSet <Racun> >(); mockContext.Setup(m => m.Racuni).Returns(mockSet.Object); var controller = new RacunController(mockContext.Object); controller.ModelState.AddModelError("RezervacijaID", "Reservation id must contain a valid value"); var newReceipt = new Racun() { RacunID = 1, IznosUkupno = 0, Placeno = false, RezervacijaID = -1, }; controller.Create(newReceipt, new Rezervacija(), ID); Assert.IsNotNull(newReceipt, "There is no data in the receipts"); Assert.IsTrue(controller.ViewData.ModelState.IsValid == false, "Reservation id is required"); }