Mini Shell

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Test cases for twisted.words.xish.utility
"""


from collections import OrderedDict

from twisted.trial import unittest
from twisted.words.xish import utility
from twisted.words.xish.domish import Element
from twisted.words.xish.utility import EventDispatcher


class CallbackTracker:
    """
    Test helper for tracking callbacks.

    Increases a counter on each call to L{call} and stores the object
    passed in the call.
    """

    def __init__(self):
        self.called = 0
        self.obj = None

    def call(self, obj):
        self.called = self.called + 1
        self.obj = obj


class OrderedCallbackTracker:
    """
    Test helper for tracking callbacks and their order.
    """

    def __init__(self):
        self.callList = []

    def call1(self, object):
        self.callList.append(self.call1)

    def call2(self, object):
        self.callList.append(self.call2)

    def call3(self, object):
        self.callList.append(self.call3)


class EventDispatcherTests(unittest.TestCase):
    """
    Tests for L{EventDispatcher}.
    """

    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.assertEqual(cb1.called, 2)
        self.assertEqual(cb1.obj, msg)
        self.assertEqual(cb2.called, 0)

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

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

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

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

        When the event is dispatched 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.assertEqual(cb1.called, 1)
        self.assertEqual(cb1.obj, d)
        self.assertEqual(cb2.called, 1)
        self.assertEqual(cb2.obj, d)

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

        def onMessage(_):
            d.addObserver("/message", cb.call)

        d.addOnetimeObserver("/message", onMessage)

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

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

        d.dispatch(msg)
        self.assertEqual(cb.called, 2)

    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.assertEqual(cb.called, 0)

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

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

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

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

    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.assertEqual(False, result)

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

    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.assertEqual(
            cb.callList,
            [cb.call1, cb.call2, cb.call3],
            "Calls out of order: %s" % repr([c.__name__ for c in cb.callList]),
        )

    # Observers are put into CallbackLists that are then put into dictionaries
    # keyed by the event trigger. Upon removal of the last observer for a
    # particular event trigger, the (now empty) CallbackList and corresponding
    # event trigger should be removed from those dictionaries to prevent
    # slowdown and memory leakage.

    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_cleanUpRemoveXPathObserver(self):
        """
        Test observer clean-up after removeObserver for XPath events.
        """

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

        d.addObserver("/message", cb.call)
        d.dispatch(msg)
        self.assertEqual(1, cb.called)
        d.removeObserver("/message", cb.call)
        self.assertEqual(0, len(d._xpathObservers.pop(0)))

    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 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)))

    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


class XmlPipeTests(unittest.TestCase):
    """
    Tests for L{twisted.words.xish.utility.XmlPipe}.
    """

    def setUp(self):
        self.pipe = utility.XmlPipe()

    def test_sendFromSource(self):
        """
        Send an element from the source and observe it from the sink.
        """

        def cb(obj):
            called.append(obj)

        called = []
        self.pipe.sink.addObserver('/test[@xmlns="testns"]', cb)
        element = Element(("testns", "test"))
        self.pipe.source.send(element)
        self.assertEqual([element], called)

    def test_sendFromSink(self):
        """
        Send an element from the sink and observe it from the source.
        """

        def cb(obj):
            called.append(obj)

        called = []
        self.pipe.source.addObserver('/test[@xmlns="testns"]', cb)
        element = Element(("testns", "test"))
        self.pipe.sink.send(element)
        self.assertEqual([element], called)