def METHOD_NAME(self):
    # The basket is empty. No offers are applied.
    self.assertEqual(
        self.offer1.get_upsell_message(self.basket),
        "Buy 2 more products from All products",
    )
    self.assertEqual(
        self.offer2.get_upsell_message(self.basket),
        "Spend £1.99 more from All products",
    )
    self.assertEqual(
        self.offer3.get_upsell_message(self.basket),
        "Buy 1 more product from All products",
    )
    self.add_product()
    # 1 product in the basket. Offer #2 is applied.
    self.assertOffersApplied([self.offer2])
    self.assertEqual(
        self.offer1.get_upsell_message(self.basket),
        "Buy 1 more product from All products",
    )
    self.assertIsNone(self.offer2.get_upsell_message(self.basket))
    self.assertEqual(
        self.offer3.get_upsell_message(self.basket),
        "Buy 1 more product from All products",
    )
    self.add_product()
    # 2 products in the basket. Offers #1 is applied.
    self.assertOffersApplied([self.offer1])
    self.assertIsNone(self.offer1.get_upsell_message(self.basket))
    self.assertEqual(
        self.offer2.get_upsell_message(self.basket),
        "Spend £1.99 more from All products",
    )
    self.assertEqual(
        self.offer3.get_upsell_message(self.basket),
        "Buy 1 more product from All products",
    )
    self.add_product()
    # 3 products in the basket. Offers #1 and #2 are applied.
    self.assertOffersApplied([self.offer1, self.offer2])
    self.assertIsNone(self.offer1.get_upsell_message(self.basket))
    self.assertIsNone(self.offer2.get_upsell_message(self.basket))
    self.assertEqual(
        self.offer3.get_upsell_message(self.basket),
        "Buy 1 more product from All products",
    )
    self.add_product()
    # 4 products in the basket. All offers are applied.
    self.assertOffersApplied([self.offer1, self.offer2, self.offer3])
    self.assertIsNone(self.offer1.get_upsell_message(self.basket))
    self.assertIsNone(self.offer2.get_upsell_message(self.basket))
    self.assertIsNone(self.offer3.get_upsell_message(self.basket))