def test_cleanUpOnetimeEventObserver(self):
        """
        Test observer clean-up after onetime named events.
        """

        d = EventDispatcher()
        cb = CallbackTracker()

        d.addOnetimeObserver('//event/test', cb.call)
        d.dispatch(None, '//event/test')
        self.assertEqual(1, cb.called)
        self.assertEqual(0, len(d._eventObservers.pop(0)))

    def testDispatcherResult(self):
        d = EventDispatcher()
        msg = Element(("ns", "message"))
        pres = Element(("ns", "presence"))
        cb = CallbackTracker()

        d.addObserver("/presence", cb.call)
        result = d.dispatch(msg)
        self.assertEquals(False, result)

        result = d.dispatch(pres)
        self.assertEquals(True, result)

    def test_cleanUpOnetimeXPathObserver(self):
        """
        Test observer clean-up after onetime XPath events.
        """

        d = EventDispatcher()
        cb = CallbackTracker()
        msg = Element((None, "message"))

        d.addOnetimeObserver('/message', cb.call)
        d.dispatch(msg)
        self.assertEqual(1, cb.called)
        self.assertEqual(0, len(d._xpathObservers.pop(0)))

class XmlStreamStub(object):
    """
    Stub for testing objects that communicate through XML Streams.

    Instances of this stub hold an object in L{xmlstream} that acts like an
    L{XmlStream<twisted.words.xish.xmlstream.XmlStream} after connection stream
    initialization. Stanzas can be sent through it by calling its C{send}
    method with an object implementing
    L{IElement<twisted.words.xish.domish.IElement>} as its first argument.
    These appear in sequence in the L{output} instance variable of the stub.

    For the reverse direction, stanzas passed to L{send} of the stub, will be
    dispatched in the stubbed XmlStream as if it was received over the wire, so
    that registered observers will be called.

    Example::

        >>> stub = XmlStreamStub()
        >>> stub.xmlstream.send(domish.Element((None, 'presence')))
        >>> stub.output[-1].toXml()
        u'<presence/>'
        >>> def cb(stanza):
        ...     print("Got: %r" stanza.toXml())
        >>> stub.xmlstream.addObserver('/presence')
        >>> stub.send(domish.Element((None, 'presence')))
        Got: u'<presence/>'

    @ivar xmlstream: Stubbed XML Stream.
    @type xmlstream: L{EventDispatcher}
    @ivar output: List of stanzas sent to the XML Stream.
    @type output: L{list}
    """

    def __init__(self):
        self.output = []
        self.xmlstream = EventDispatcher()
        self.xmlstream.send = self.output.append

    def send(self, obj):
        """
        Pass an element to the XML Stream as if received.

        @param obj: Element to be dispatched to C{self.xmlstream}.
        @type obj: object implementing
                   L{IElement<twisted.words.xish.domish.IElement>}.
        """
        self.xmlstream.dispatch(obj)

    def testOrderedXPathDispatch(self):
        d = EventDispatcher()
        cb = OrderedCallbackTracker()
        d.addObserver("/message/body", cb.call2)
        d.addObserver("/message", cb.call3, -1)
        d.addObserver("/message/body", cb.call1, 1)

        msg = Element(("ns", "message"))
        msg.addElement("body")
        d.dispatch(msg)
        self.assertEquals(cb.callList, [cb.call1, cb.call2, cb.call3],
                          "Calls out of order: %s" %
                          repr([c.__name__ for c in cb.callList]))

    def test_addObserverTwice(self):
        """
        Test adding two observers for the same query.

        When the event is dispath both of the observers need to be called.
        """
        d = EventDispatcher()
        cb1 = CallbackTracker()
        cb2 = CallbackTracker()

        d.addObserver("//event/testevent", cb1.call)
        d.addObserver("//event/testevent", cb2.call)
        d.dispatch(d, "//event/testevent")

        self.assertEquals(cb1.called, 1)
        self.assertEquals(cb1.obj, d)
        self.assertEquals(cb2.called, 1)
        self.assertEquals(cb2.obj, d)

    def testOnetimeDispatch(self):
        d = EventDispatcher()
        msg = Element(("ns", "message"))
        cb = CallbackTracker()

        d.addOnetimeObserver("/message", cb.call)
        d.dispatch(msg)
        self.assertEquals(cb.called, 1)
        d.dispatch(msg)
        self.assertEquals(cb.called, 1)

 def testAddObserverInDispatch(self):
     # Test for registration of events during dispatch
     d = EventDispatcher()
     msg = Element(("ns", "message"))
     pres = Element(("ns", "presence"))
     cb = CallbackTracker2(d)
     
     d.addObserver("/message", cb.call2)
     d.dispatch(msg)
     self.assertEquals(cb.called, 0)
     d.dispatch(pres)
     self.assertEquals(cb.called, 1)

    def test_cleanUpRemoveEventObserver(self):
        """
        Test observer clean-up after removeObserver for named events.
        """

        d = EventDispatcher()
        cb = CallbackTracker()

        d.addObserver("//event/test", cb.call)
        d.dispatch(None, "//event/test")
        self.assertEqual(1, cb.called)
        d.removeObserver("//event/test", cb.call)
        self.assertEqual(0, len(d._eventObservers.pop(0)))

    def test_addOnetimeObserverInDispatch(self):
        """
        Test for registration of a onetime observer during dispatch.
        """
        d = EventDispatcher()
        msg = Element(("ns", "message"))
        cb = CallbackTracker()

        def onMessage(msg):
            d.addOnetimeObserver("/message", cb.call)

        d.addOnetimeObserver("/message", onMessage)

        d.dispatch(msg)
        self.assertEquals(cb.called, 0)

        d.dispatch(msg)
        self.assertEquals(cb.called, 1)

        d.dispatch(msg)
        self.assertEquals(cb.called, 1)

    def test_observerRaisingException(self):
        """
        Test that exceptions in observers do not bubble up to dispatch.

        The exceptions raised in observers should be logged and other
        observers should be called as if nothing happened.
        """

        class OrderedCallbackList(utility.CallbackList):
            def __init__(self):
                self.callbacks = OrderedDict()

        class TestError(Exception):
            pass

        def raiseError(_):
            raise TestError()

        d = EventDispatcher()
        cb = CallbackTracker()

        originalCallbackList = utility.CallbackList

        try:
            utility.CallbackList = OrderedCallbackList

            d.addObserver('//event/test', raiseError)
            d.addObserver('//event/test', cb.call)
            try:
                d.dispatch(None, '//event/test')
            except TestError:
                self.fail("TestError raised. Should have been logged instead.")

            self.assertEqual(1, len(self.flushLoggedErrors(TestError)))
            self.assertEqual(1, cb.called)
        finally:
            utility.CallbackList = originalCallbackList

 def __init__(self, *args, **kw):
     service.MultiService.__init__(self, *args, **kw)
     EventDispatcher.__init__(self, *args, **kw)
     self.components = {}

    def testStuff(self):
        d = EventDispatcher()
        cb1 = CallbackTracker()
        cb2 = CallbackTracker()
        cb3 = CallbackTracker()

        d.addObserver("/message/body", cb1.call)
        d.addObserver("/message", cb1.call)
        d.addObserver("/presence", cb2.call)
        d.addObserver("//event/testevent", cb3.call)

        msg = Element(("ns", "message"))
        msg.addElement("body")

        pres = Element(("ns", "presence"))
        pres.addElement("presence")

        d.dispatch(msg)
        self.assertEquals(cb1.called, 2)
        self.assertEquals(cb1.obj, msg)
        self.assertEquals(cb2.called, 0)

        d.dispatch(pres)
        self.assertEquals(cb1.called, 2)
        self.assertEquals(cb2.called, 1)
        self.assertEquals(cb2.obj, pres)
        self.assertEquals(cb3.called, 0)

        d.dispatch(d, "//event/testevent")
        self.assertEquals(cb3.called, 1)
        self.assertEquals(cb3.obj, d)

        d.removeObserver("/presence", cb2.call)
        d.dispatch(pres)
        self.assertEquals(cb2.called, 1)

 def __init__(self):
     self.output = []
     self.xmlstream = EventDispatcher()
     self.xmlstream.send = self.output.append

 def __init__(self, **kwargs):
     EventDispatcher.__init__(self, **kwargs)
     self.listener = {}