public void IssueDiscountGoodPostTest()
{
var mock = new Mock<IDiscountService>();
// set the mock object to the object of discountTest
discountTest.discountService = mock.Object;
// pass in the coupon
discountTest.IssueDiscount(coupon);
// verifies!
mock.Verify(mockedObject => mockedObject.CreateCoupon(coupon));
}