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# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Test cases for L{twisted.logger._observer}.
"""
from typing import Dict, List, Tuple, cast
from zope.interface import implementer
from zope.interface.exceptions import BrokenMethodImplementation
from zope.interface.verify import verifyObject
from twisted.trial import unittest
from .._interfaces import ILogObserver, LogEvent
from .._logger import Logger
from .._observer import LogPublisher
class LogPublisherTests(unittest.TestCase):
"""
Tests for L{LogPublisher}.
"""
def test_interface(self) -> None:
"""
L{LogPublisher} is an L{ILogObserver}.
"""
publisher = LogPublisher()
try:
verifyObject(ILogObserver, publisher)
except BrokenMethodImplementation as e:
self.fail(e)
def test_observers(self) -> None:
"""
L{LogPublisher.observers} returns the observers.
"""
o1 = cast(ILogObserver, lambda e: None)
o2 = cast(ILogObserver, lambda e: None)
publisher = LogPublisher(o1, o2)
self.assertEqual({o1, o2}, set(publisher._observers))
def test_addObserver(self) -> None:
"""
L{LogPublisher.addObserver} adds an observer.
"""
o1 = cast(ILogObserver, lambda e: None)
o2 = cast(ILogObserver, lambda e: None)
o3 = cast(ILogObserver, lambda e: None)
publisher = LogPublisher(o1, o2)
publisher.addObserver(o3)
self.assertEqual({o1, o2, o3}, set(publisher._observers))
def test_addObserverNotCallable(self) -> None:
"""
L{LogPublisher.addObserver} refuses to add an observer that's
not callable.
"""
publisher = LogPublisher()
self.assertRaises(TypeError, publisher.addObserver, object())
def test_removeObserver(self) -> None:
"""
L{LogPublisher.removeObserver} removes an observer.
"""
o1 = cast(ILogObserver, lambda e: None)
o2 = cast(ILogObserver, lambda e: None)
o3 = cast(ILogObserver, lambda e: None)
publisher = LogPublisher(o1, o2, o3)
publisher.removeObserver(o2)
self.assertEqual({o1, o3}, set(publisher._observers))
def test_removeObserverNotRegistered(self) -> None:
"""
L{LogPublisher.removeObserver} removes an observer that is not
registered.
"""
o1 = cast(ILogObserver, lambda e: None)
o2 = cast(ILogObserver, lambda e: None)
o3 = cast(ILogObserver, lambda e: None)
publisher = LogPublisher(o1, o2)
publisher.removeObserver(o3)
self.assertEqual({o1, o2}, set(publisher._observers))
def test_fanOut(self) -> None:
"""
L{LogPublisher} calls its observers.
"""
event = dict(foo=1, bar=2)
events1: List[LogEvent] = []
events2: List[LogEvent] = []
events3: List[LogEvent] = []
o1 = cast(ILogObserver, events1.append)
o2 = cast(ILogObserver, events2.append)
o3 = cast(ILogObserver, events3.append)
publisher = LogPublisher(o1, o2, o3)
publisher(event)
self.assertIn(event, events1)
self.assertIn(event, events2)
self.assertIn(event, events3)
def test_observerRaises(self) -> None:
"""
Observer raises an exception during fan out: a failure is logged, but
not re-raised. Life goes on.
"""
event = dict(foo=1, bar=2)
exception = RuntimeError("ARGH! EVIL DEATH!")
events: List[LogEvent] = []
@implementer(ILogObserver)
def observer(event: LogEvent) -> None:
shouldRaise = not events
events.append(event)
if shouldRaise:
raise exception
collector: List[LogEvent] = []
publisher = LogPublisher(observer, cast(ILogObserver, collector.append))
publisher(event)
# Verify that the observer saw my event
self.assertIn(event, events)
# Verify that the observer raised my exception
errors = [e["log_failure"] for e in collector if "log_failure" in e]
self.assertEqual(len(errors), 1)
self.assertIs(errors[0].value, exception)
# Make sure the exceptional observer does not receive its own error.
self.assertEqual(len(events), 1)
def test_observerRaisesAndLoggerHatesMe(self) -> None:
"""
Observer raises an exception during fan out and the publisher's Logger
pukes when the failure is reported. The exception does not propagate
back to the caller.
"""
event = dict(foo=1, bar=2)
exception = RuntimeError("ARGH! EVIL DEATH!")
@implementer(ILogObserver)
def observer(event: LogEvent) -> None:
raise RuntimeError("Sad panda")
class GurkLogger(Logger):
def failure(self, *args: object, **kwargs: object) -> None:
raise exception
publisher = LogPublisher(observer)
publisher.log = GurkLogger()
publisher(event)
# Here, the lack of an exception thus far is a success, of sorts
def test_trace(self) -> None:
"""
Tracing keeps track of forwarding to observers.
"""
event = dict(foo=1, bar=2, log_trace=[])
traces: Dict[int, Tuple[Tuple[Logger, ILogObserver]]] = {}
# Copy trace to a tuple; otherwise, both observers will store the same
# mutable list, and we won't be able to see o1's view distinctly.
@implementer(ILogObserver)
def o1(e: LogEvent) -> None:
traces.setdefault(
1, cast(Tuple[Tuple[Logger, ILogObserver]], tuple(e["log_trace"]))
)
@implementer(ILogObserver)
def o2(e: LogEvent) -> None:
traces.setdefault(
2, cast(Tuple[Tuple[Logger, ILogObserver]], tuple(e["log_trace"]))
)
publisher = LogPublisher(o1, o2)
publisher(event)
self.assertEqual(traces[1], ((publisher, o1),))
self.assertEqual(traces[2], ((publisher, o1), (publisher, o2)))
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