public int GetPriceForPottersTest(int[] bookAmounts)
        {
            var target = new PotterShoppingCart();

            for (var i = 0; i < 5; i++)
            {
                if (bookAmounts[i] > 0)
                {
                    target.AddPotterBook(Potters[i], bookAmounts[i]);
                }
            }

            return(target.Checkout());
        }