def test_smtpapiheader_asjson(self):
     """Test SendGrid SMTP headers work as JSON"""
     expected = '{"category": "Transactional"}'
     h = SmtpApiHeader()
     h.set_category("Transactional")
     # yes, it says asJSON, but it's a string of JSON not a JSON object
     self.assertEqual(h.as_json(), expected)