class PingMessageSerializerTestCase(unittest.TestCase):
    def setUp(self):
        self.serializer = PingMessageSerializer()

    def test_serialize_with_id(self):
        id = 'test'
        pod = self.serializer.serialize(PingMessage(id=id))
        self.assertEqual(pod, {'msg': 'ping', 'id': id})

    def test_serialize_without_id(self):
        pod = self.serializer.serialize(PingMessage())
        self.assertEqual(pod, {'msg': 'ping'})
 def setUp(self):
     self.serializer = PingMessageSerializer()