public void Checkout_ValidShoppingCart_Succeeds()
        {
            var shoppingCart = new ShoppingCart();

            shoppingCart.Add(new CartItem(2, 1));
            shoppingCart.CheckOut(3, "4242424242424242", 4, "111");

            Assert.AreNotEqual(0, PurchaseHistoryRepository.Instance.FindForCustomer(3));
        }