def METHOD_NAME(self):
    response = self.client.get(reverse('admin:diving_level_add'))
    csrf = self.get_csrf_token(response)
    post_data = {'id': self.level.pk,
                 'name_en': 'Dur-dur',
                 'csrfmiddlewaretoken': csrf}
    response = self.client.post(reverse('admin:diving_level_add'), post_data)
    error_msg = "Level with id &#x27;%s&#x27; already exists" % self.level.pk
    self.assertContains(response, error_msg)