Adds some WebSocketHandler tests that actually connect using a WS client and
plugs a potential race condition.
Any call to write_message could fail, either due to WebSocketClosedError like
in the log below, or simply due to socket errors. To play it safe we catch all
errors and debug log that a broadcast failed.
2015-02-26 21:24:02,266 ERROR [HttpServer] /home/adamcik/dev/mopidy/mopidy/http/handlers.py:116
mopidy.http.handlers WebSocket request error: deque index out of range
2015-02-26 21:24:10,098 ERROR [HttpFrontend-11] build/bdist.linux-x86_64/egg/pykka/actor.py:268
pykka Unhandled exception in HttpFrontend (urn:uuid:e376bd95-c32e-4e17-ad20-7d0b3c0cf2b2):
Traceback (most recent call last):
File "build/bdist.linux-x86_64/egg/pykka/actor.py", line 200, in _actor_loop
response = self._handle_receive(message)
File "build/bdist.linux-x86_64/egg/pykka/actor.py", line 294, in _handle_receive
return callee(*message['args'], **message['kwargs'])
File ".../dev/mopidy/mopidy/http/actor.py", line 77, in on_event
on_event(name, **data)
File ".../dev/mopidy/mopidy/http/actor.py", line 84, in on_event
handlers.WebSocketHandler.broadcast(message)
File ".../dev/mopidy/mopidy/http/handlers.py", line 78, in broadcast
client.write_message(msg)
File ".../dev/mopidy-virtualenv/local/lib/python2.7/site-packages/tornado/websocket.py", line 183, in write_message
raise WebSocketClosedError()
WebSocketClosedError
