public void Clear_AddValidItemToCartThenClear_TotalEquals0()
        {
            IProductRepository products = A.Fake<IProductRepository>();
            ShoppingCart shoppingCart = new ShoppingCart(products);

            A.CallTo(() => products.GetProductById("item-1")).Returns(new Product("item-1", "Banana", 14.5));

            shoppingCart.AddItem("item-1");
            shoppingCart.Clear();

            Assert.That(shoppingCart.Total, Is.EqualTo(0));
        }