public void GetTotalValueForfourSameProductC()
        {
            //Arrange
            PointOfSaleTerminal pointOfSale = new PointOfSaleTerminal();
            Product             product     = new Product("C", 5, 1);

            //Act
            pointOfSale.ScanProduct(product);

            //Assert
            Assert.AreEqual(5, pointOfSale.DiscountForC("C"));
        }