As a customer with both rental and non-rental items in my cart, I want to receive an additional discount on my order, so that I am rewarded for combining product types.
Given my cart contains at least one rental item and at least one non-rental item Then an additional 15% discount is applied to the cart subtotal.
Given the combination discount is applied Then the cart shows the subtotal, discount percentage (15%), discount amount, and final total.
Given I remove all rental items or all non-rental items from my cart Then the 15% combination discount is removed And the total reverts to the regular subtotal.
Given I complete checkout with the combination discount applied Then the invoice shows the subtotal, the 15% discount amount, and the final total.