Public API decorator and public vs private members / ctor

buildbot.test.unit.test_mq_wamp
  WampMQ
    test_forward_data ...                                               [ERROR]

===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/Users/ptardy/dev/bb/buildbot/.venv/lib/python2.7/site-packages/twisted/internet/defer.py", line 1301, in _inlineCallbacks
    result = g.send(result)
  File "/Users/ptardy/dev/bb/buildbot/master/buildbot/test/unit/test_mq_wamp.py", line 135, in test_forward_data
    yield self.mq._produce(('a', 'b'), 'foo')
  File "/Users/ptardy/dev/bb/buildbot/master/buildbot/mq/wamp.py", line 62, in _produce
    return self.master.wamp.publish(self.messageTopic(routingKey), _data, options=options)
  File "/Users/ptardy/dev/bb/buildbot/master/buildbot/test/unit/test_mq_wamp.py", line 70, in publish
    details = EventDetails(1, topic=topic)
exceptions.TypeError: __init__() takes at least 3 arguments (3 given)

investigating..

Start with the failing test in buildbot/test/unit/test_mq_wamp.py and the _produce entry point in buildbot/mq/wamp.py. Inspect the EventDetails call in the test and its constructor contract, then determine the intended public versus private API and constructor behavior; the issue is done when the failure is resolved and the relevant test passes.