'Test the response given an invalid username.'

def test_invalid_username(self):

    response = self.request_bulk_enroll({'identifiers': 'percivaloctavius', 'action': 'enroll', 'email_students': False, 'courses': self.course_key})
    self.assertEqual(response.status_code, 200)
    expected = {'action': 'enroll', 'auto_enroll': False, 'email_students': False, 'courses': {self.course_key: {'action': 'enroll', 'auto_enroll': False, 'results': [{'identifier': 'percivaloctavius', 'invalidIdentifier': True}]}}}
    res_json = json.loads(response.content)
    self.assertEqual(res_json, expected)
