new_contents: from unittest import TestCase
  from unittest.mock import Mock
  
  from opwen_email_server.services.auth import AzureAuth
  
  
  class AzureAuthTests(TestCase):
      # noinspection PyTypeChecker
      def setUp(self):
          self.mock_client = Mock()
          self.auth = AzureAuth(account='account', key='key', table='table',
                                client=self.mock_client)
  
      def test_retrieves_inserted(self):
          self.given_clients(('client', 'domain'))
  
          actual_domain = self.auth.domain_for('client')
  
          self.assertEqual(actual_domain, 'domain')
  
      def test_retrieves_none_for_missing(self):
          self.given_clients()
  
          actual_domain = self.auth.domain_for('client')
  
          self.assertIsNone(actual_domain)
  
      def given_clients(self, *clients_and_domains):
          self.mock_client.query_entities.return_value = ({
              'RowKey': client_id,
              'PartitionKey': client_id,
              'domain': domain
          } for (client_id, domain) in clients_and_domains)
  
subject: Add tests for AzureAuth