text: from django.test import TestCase
  from django.contrib.auth import get_user_model
  from checkout.models import OrderLineItem, BillingAddress
  
  # Create your tests here.
  
  
  class TestCheckoutModels(TestCase):
  
      def test_can_create_a_order_line_item(self):
          orderlineitem = OrderLineItem(order_id=3,
                                        product_id=1,
                                        quantity=2,
                                        size='Large')
          orderlineitem.save()
          self.assertEqual(orderlineitem.order_id, 3)
          self.assertEqual(orderlineitem.product_id, 1)
          self.assertEqual(orderlineitem.quantity, 2)
          self.assertEqual(orderlineitem.size, 'Large')
  
      def test_can_create_a_billing_address(self):
          user = get_user_model().objects.create(username='testuser')
          billingadress = BillingAddress(user_id=1,
                                         Full_Name="Test",
                                         country='wales',
                                         postcode='x1x2x3',
                                         town_or_City="Newport",
                                         Address_Line_1="x street",
                                         Address_Line_2="x place",
                                         county="Gwent",
                                         date="2011-11-11")
          billingadress.save()
          self.assertEqual(billingadress.user_id, 1)
          self.assertEqual(billingadress.Full_Name, 'Test')
          self.assertEqual(billingadress.country, 'wales')
          self.assertEqual(billingadress.postcode, 'x1x2x3')
          self.assertEqual(billingadress.town_or_City, 'Newport')
          self.assertEqual(billingadress.Address_Line_1, 'x street')
          self.assertEqual(billingadress.Address_Line_2, 'x place')
          self.assertEqual(billingadress.county, 'Gwent')
          self.assertEqual(billingadress.date, '2011-11-11')
  