public void AddPrescriptionToBill_NoneExistsBillId_ThrowArgumentOutOfRangeException() { prescription validPrescription = new prescription(); int NoneExistsBillId = -1; Action act = () => _sut.AddPrescriptionToBill(NoneExistsBillId, validPrescription); act.Should().Throw <ArgumentOutOfRangeException>() .WithMessage("Bill Khong Ton Tai\nParameter name: billId"); }