code: from django.test import SimpleTestCase
  from django.utils.connection import BaseConnectionHandler
  
  
  class BaseConnectionHandlerTests(SimpleTestCase):
      def test_create_connection(self):
          handler = BaseConnectionHandler()
          msg = 'Subclasses must implement create_connection().'
          with self.assertRaisesMessage(NotImplementedError, msg):
              handler.create_connection(None)
  