'Test that a request for a nonexistent username returns an error.'

def test_nonexistent_user(self):

    resp = self.client.get(self.get_url('IDoNotExist'))
    self.assertEqual(resp.status_code, status.HTTP_403_FORBIDDEN)
    self.assertIn('error_code', resp.data)
    self.assertEqual(resp.data['error_code'], 'user_mismatch')
