new_contents: from django.test import TestCase
  
  from administrator.models import User, UserManager
  
  
  class UserManagerTestCase(TestCase):
      valid_email = 'example@example.com'
      valid_username = 'foobar'
      valid_password = 'qwerty123'
  
      def setUp(self):
          self.user_manager = UserManager()
          self.user_manager.model = User
  
      def test_user_is_not_created_without_email(self):
          with self.assertRaises(ValueError):
              self.user_manager.create_user('', '', '')
  
      def test_user_is_created(self):
          user = self.user_manager.create_user(self.valid_email, self.valid_username, self.valid_password)
          self.assertEqual(user.is_superuser, False)
  
      def test_superuser_is_not_created_with_is_superuser_field_set_to_false(self):
          with self.assertRaises(ValueError):
              self.user_manager.create_superuser(self.valid_email, self.valid_username, self.valid_password,
                                                 is_superuser=False)
  
      def test_superuser_is_created(self):
          superuser = self.user_manager.create_user(self.valid_email, self.valid_username, self.valid_password)
          self.assertEqual(superuser.is_superuser, True)
  
  
  class UserTestCase(TestCase):
      valid_email = 'example@example.com'
  
      def setUp(self):
          self.user = User()
          self.user.email = self.valid_email
  
      def test_user_status_can_be_set_to_active(self):
          self.user.set_status_and_is_active(0)
          self.assertEqual(self.user.status, 0)
          self.assertEqual(self.user.is_active, True)
  
      def test_user_status_can_be_set_to_inactive(self):
          self.user.set_status_and_is_active(1)
          self.assertEqual(self.user.status, 1)
          self.assertEqual(self.user.is_active, False)
  
      def test_user_has_email_as_his_short_name(self):
          short_name = self.user.get_short_name()
          self.assertEqual(short_name, self.user.email)
  
subject: Add tests for User model