public void AccountHasDiscountOfferTest_DiscountOfferAmountNull()
        {
            AccountSummary account = new AccountSummary()
            {
                DiscountOfferAmount = null,
                DiscountOfferExpiry = DateTime.Now
            };

            bool expected = false;
            bool result   = _helper.AccountHasDiscountOffer(account);

            Assert.AreEqual(expected, result);
        }