def METHOD_NAME(self):
    self.assertFalse(self.order_line.user_discount_value)
    self.assertFalse(self.order_line.user_total_discount)
    self.assertTrue(self.order_line.need_change_discount_value())
    order = Form(self.order)
    with order.order_line.edit(0) as line:
        line.discount = 33
        self.assertEqual(line.discount_value, 330)
        line.price_unit = 2000
        self.assertEqual(line.discount_value, 660)
        with self.assertRaises(AssertionError):
            line.discount_value = 20