public void WhenItemsInCartThenReturnSumOfItemPricesForGetPrice()
        {
            var cart = new CartEntity();

            cart.Items.Add(Mock.Of <CartItem>(ci => ci.GetPrice() == 10.0));
            cart.Items.Add(Mock.Of <CartItem>(ci => ci.GetPrice() == 20.0));

            cart.GetPrice().Should().Be(30.0);
        }
        public void WhenNoItemsInCartThenReturnZeroForGetPrice()
        {
            var cart = new CartEntity();

            cart.GetPrice().Should().Be(0.0);
        }