def test_discount_applies_to_most_expensive_item(self):

        self.add_discount_prod_1_includes_cat_2(quantity=1)

        cart = TestingCartController.for_user(self.USER_1)

        cart.add_to_cart(self.PROD_1, 1)  # Enable the discount

        import itertools

        prods = (self.PROD_3, self.PROD_4)

        for first, second in itertools.permutations(prods, 2):

            cart.set_quantity(first, 1)

            cart.set_quantity(second, 1)

            # There should only be one discount

            discount_items = list(cart.cart.discountitem_set.all())

            self.assertEqual(1, len(discount_items))

            # It should always apply to PROD_3, as it costs more.

            self.assertEqual(discount_items[0].product, self.PROD_3)

            cart.set_quantity(first, 0)

            cart.set_quantity(second, 0)