public void Then_the_product_should_be_removed()
        {
            var newQty = 0;

            _basket.ChangeQtyOfProduct(newQty, _product);

            _basket.Items().FirstOrDefault(i => i.Product == _product).Qty.Should().Be(0);
        }
        public void Then_the_quantity_of_that_product_should_update_to_match()
        {
            var newQty = 5;

            _basket.ChangeQtyOfProduct(newQty, _product);

            _basket.Items().FirstOrDefault(i => i.Product == _product).Qty
            .Should().Be(newQty);
        }