Current File : //lib/python3/dist-packages/twisted/test/test_defer.py
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Test cases for L{twisted.internet.defer}.
"""
from __future__ import annotations
import contextvars
import functools
import gc
import re
import traceback
import types
import unittest as pyunit
import warnings
import weakref
from asyncio import (
AbstractEventLoop,
CancelledError,
Future,
new_event_loop as _new_event_loop,
)
from typing import (
Any,
Callable,
Coroutine,
Dict,
Generator,
List,
Mapping,
NoReturn,
Optional,
Set,
Tuple,
Type,
TypeVar,
Union,
cast,
)
from hamcrest import assert_that, empty, equal_to
from hypothesis import given
from hypothesis.strategies import integers
from typing import assert_type
from twisted.internet import defer, reactor
from twisted.internet.defer import (
_T,
Deferred,
DeferredFilesystemLock,
DeferredList,
DeferredLock,
DeferredQueue,
DeferredSemaphore,
FailureGroup,
_DeferredListResultListT,
_DeferredListSingleResultT,
ensureDeferred,
race,
)
from twisted.internet.task import Clock
from twisted.python import log
from twisted.python.compat import _PYPY
from twisted.python.failure import Failure
from twisted.trial import unittest
def ensuringDeferred(
f: Callable[..., Coroutine[Deferred[Any], Any, _T]]
) -> Callable[..., Deferred[_T]]:
@functools.wraps(f)
def wrapper(*args: object, **kwargs: object) -> Deferred[_T]:
coro = f(*args, **kwargs)
return Deferred.fromCoroutine(coro)
return wrapper
class GenericError(Exception):
pass
def getDivisionFailure(*args: object, **kwargs: object) -> Failure:
"""
Make a L{Failure} of a divide-by-zero error.
@param args: Any C{*args} are passed to Failure's constructor.
@param kwargs: Any C{**kwargs} are passed to Failure's constructor.
"""
try:
1 / 0
except BaseException:
f = Failure(*args, **kwargs)
return f
def fakeCallbackCanceller(deferred: Deferred[str]) -> None:
"""
A fake L{Deferred} canceller which callbacks the L{Deferred}
with C{str} "Callback Result" when cancelling it.
@param deferred: The cancelled L{Deferred}.
"""
deferred.callback("Callback Result")
_ExceptionT = TypeVar("_ExceptionT", bound=Exception)
class ImmediateFailureMixin:
"""
Add additional assertion methods.
"""
def assertImmediateFailure(
self, deferred: Deferred[Any], exception: Type[_ExceptionT]
) -> _ExceptionT:
"""
Assert that the given Deferred current result is a Failure with the
given exception.
@return: The exception instance in the Deferred.
"""
testCase = cast(unittest.TestCase, self)
failures: List[Failure] = []
deferred.addErrback(failures.append)
testCase.assertEqual(len(failures), 1)
testCase.assertTrue(failures[0].check(exception))
return cast(_ExceptionT, failures[0].value)
class UtilTests(unittest.TestCase):
"""
Tests for utility functions.
"""
def test_logErrorReturnsError(self) -> None:
"""
L{defer.logError} returns the given error.
"""
error = Failure(RuntimeError())
result = defer.logError(error)
self.flushLoggedErrors(RuntimeError)
self.assertIs(error, result)
def test_logErrorLogsError(self) -> None:
"""
L{defer.logError} logs the given error.
"""
error = Failure(RuntimeError())
defer.logError(error)
errors = self.flushLoggedErrors(RuntimeError)
self.assertEqual(errors, [error])
def test_logErrorLogsErrorNoRepr(self) -> None:
"""
The text logged by L{defer.logError} has no repr of the failure.
"""
output = []
def emit(eventDict: Dict[str, Any]) -> None:
text = log.textFromEventDict(eventDict)
assert text is not None
output.append(text)
log.addObserver(emit)
error = Failure(RuntimeError())
defer.logError(error)
self.flushLoggedErrors(RuntimeError)
self.assertTrue(output[0].startswith("Unhandled Error\nTraceback "))
class DeferredTests(unittest.SynchronousTestCase, ImmediateFailureMixin):
def setUp(self) -> None:
self.callbackResults: Optional[
Tuple[Tuple[object, ...], Dict[str, object]]
] = None
self.callback2Results: Optional[
Tuple[Tuple[object, ...], Dict[str, object]]
] = None
self.errbackResults: Optional[
Tuple[Tuple[Failure, ...], Dict[str, object]]
] = None
# Restore the debug flag to its original state when done.
self.addCleanup(defer.setDebugging, defer.getDebugging())
def _callback(self, *args: object, **kwargs: object) -> Any:
self.callbackResults = args, kwargs
return args[0]
def _callback2(self, *args: object, **kwargs: object) -> None:
self.callback2Results = args, kwargs
def _errback(self, *args: Failure, **kwargs: object) -> None:
self.errbackResults = args, kwargs
def testCallbackWithoutArgs(self) -> None:
deferred: Deferred[str] = Deferred()
deferred.addCallback(self._callback)
deferred.callback("hello")
self.assertIsNone(self.errbackResults)
self.assertEqual(self.callbackResults, (("hello",), {}))
def testCallbackWithArgs(self) -> None:
deferred: Deferred[str] = Deferred()
deferred.addCallback(self._callback, "world")
deferred.callback("hello")
self.assertIsNone(self.errbackResults)
self.assertEqual(self.callbackResults, (("hello", "world"), {}))
def testCallbackWithKwArgs(self) -> None:
deferred: Deferred[str] = Deferred()
deferred.addCallback(self._callback, world="world")
deferred.callback("hello")
self.assertIsNone(self.errbackResults)
self.assertEqual(self.callbackResults, (("hello",), {"world": "world"}))
def testTwoCallbacks(self) -> None:
deferred: Deferred[str] = Deferred()
deferred.addCallback(self._callback)
deferred.addCallback(self._callback2)
deferred.callback("hello")
self.assertIsNone(self.errbackResults)
self.assertEqual(self.callbackResults, (("hello",), {}))
self.assertEqual(self.callback2Results, (("hello",), {}))
def test_addCallbacksNoneErrback(self) -> None:
"""
If given None for an errback, addCallbacks uses a pass-through.
"""
error = GenericError("oopsie")
deferred: Deferred[None] = Deferred()
deferred.addCallbacks(self._callback, cast(Callable[..., object], None))
deferred.errback(error)
deferred.addErrback(self._errback)
self.assertIsNone(self.callbackResults)
assert self.errbackResults is not None
self.assertEqual(len(self.errbackResults[0]), 1)
self.assertEqual(self.errbackResults[0][0].value, error)
self.assertEqual(self.errbackResults[1], {})
def test_addCallbacksNoneCallbackArgs(self) -> None:
"""
If given None as a callback args and kwargs, () and {} are used.
"""
deferred: Deferred[str] = Deferred()
deferred.addCallbacks(
self._callback,
self._errback,
cast(Tuple[object], None),
cast(Mapping[str, object], None),
(),
{},
)
deferred.callback("hello")
self.assertIsNone(self.errbackResults)
self.assertEqual(self.callbackResults, (("hello",), {}))
def test_addCallbacksNoneErrbackArgs(self) -> None:
"""
If given None as a errback args and kwargs, () and {} are used.
"""
error = GenericError("oopsie")
deferred: Deferred[None] = Deferred()
deferred.addCallbacks(
self._callback,
self._errback,
(),
{},
cast(Tuple[object], None),
cast(Mapping[str, object], None),
)
deferred.errback(error)
deferred.addErrback(self._errback)
self.assertIsNone(self.callbackResults)
assert self.errbackResults is not None
self.assertEqual(len(self.errbackResults[0]), 1)
self.assertEqual(self.errbackResults[0][0].value, error)
self.assertEqual(self.errbackResults[1], {})
def testDeferredList(self) -> None:
ResultList = List[Tuple[bool, Union[str, Failure]]]
defr1: Deferred[str] = Deferred()
defr2: Deferred[str] = Deferred()
defr3: Deferred[str] = Deferred()
dl = DeferredList([defr1, defr2, defr3])
result: ResultList = []
def cb(resultList: ResultList, result: ResultList = result) -> None:
result.extend(resultList)
def catch(err: Failure) -> None:
return None
dl.addCallbacks(cb, cb)
defr1.callback("1")
defr2.addErrback(catch)
# "catch" is added to eat the GenericError that will be passed on by
# the DeferredList's callback on defr2. If left unhandled, the
# Failure object would cause a log.err() warning about "Unhandled
# error in Deferred". Twisted's pyunit watches for log.err calls and
# treats them as failures. So "catch" must eat the error to prevent
# it from flunking the test.
defr2.errback(GenericError("2"))
defr3.callback("3")
self.assertEqual(
[
result[0],
# result[1][1] is now a Failure instead of an Exception
(result[1][0], str(cast(Failure, result[1][1]).value)),
result[2],
],
[(defer.SUCCESS, "1"), (defer.FAILURE, "2"), (defer.SUCCESS, "3")],
)
def testEmptyDeferredList(self) -> None:
result: List[_DeferredListResultListT[None]] = []
def cb(
resultList: _DeferredListResultListT[None],
result: List[_DeferredListResultListT[None]] = result,
) -> None:
result.append(resultList)
dl1: Deferred[_DeferredListResultListT[None]] = DeferredList([])
dl1.addCallbacks(cb)
self.assertEqual(result, [[]])
result[:] = []
dl2: Deferred[_DeferredListSingleResultT[None]] = DeferredList(
[], fireOnOneCallback=True
)
dl2.addCallbacks(cb)
self.assertEqual(result, [])
def testDeferredListFireOnOneError(self) -> None:
defr1: Deferred[str] = Deferred()
defr2: Deferred[str] = Deferred()
defr3: Deferred[str] = Deferred()
dl = DeferredList([defr1, defr2, defr3], fireOnOneErrback=True)
result: List[Failure] = []
dl.addErrback(result.append)
# consume errors after they pass through the DeferredList (to avoid
# 'Unhandled error in Deferred'.
def catch(err: Failure) -> None:
return None
defr2.addErrback(catch)
# fire one Deferred's callback, no result yet
defr1.callback("1")
self.assertEqual(result, [])
# fire one Deferred's errback -- now we have a result
defr2.errback(GenericError("from def2"))
self.assertEqual(len(result), 1)
# extract the result from the list
aFailure = result[0]
# the type of the failure is a FirstError
self.assertTrue(
issubclass(aFailure.type, defer.FirstError),
"issubclass(aFailure.type, defer.FirstError) failed: "
"failure's type is %r" % (aFailure.type,),
)
firstError = aFailure.value
# check that the GenericError("2") from the deferred at index 1
# (defr2) is intact inside failure.value
self.assertEqual(firstError.subFailure.type, GenericError)
self.assertEqual(firstError.subFailure.value.args, ("from def2",))
self.assertEqual(firstError.index, 1)
def testDeferredListDontConsumeErrors(self) -> None:
d1: Deferred[None] = Deferred()
dl = DeferredList([d1])
errorTrap: List[Failure] = []
d1.addErrback(errorTrap.append)
resultLists: List[_DeferredListResultListT[None]] = []
dl.addCallback(resultLists.append)
d1.errback(GenericError("Bang"))
self.assertEqual("Bang", errorTrap[0].value.args[0])
self.assertEqual(1, len(resultLists))
firstResult = resultLists[0][0]
assert firstResult is not None
self.assertEqual("Bang", firstResult[1].value.args[0]) # type: ignore[attr-defined]
def testDeferredListConsumeErrors(self) -> None:
d1: Deferred[None] = Deferred()
dl = DeferredList([d1], consumeErrors=True)
errorTrap: List[Failure] = []
d1.addErrback(errorTrap.append)
resultLists: List[_DeferredListResultListT[None]] = []
dl.addCallback(resultLists.append)
d1.errback(GenericError("Bang"))
self.assertEqual([], errorTrap)
self.assertEqual(1, len(resultLists))
firstResult = resultLists[0][0]
assert firstResult is not None
self.assertEqual("Bang", firstResult[1].value.args[0]) # type: ignore[attr-defined]
def testDeferredListFireOnOneErrorWithAlreadyFiredDeferreds(self) -> None:
# Create some deferreds, and errback one
d1: Deferred[None] = Deferred()
d2: Deferred[None] = Deferred()
d1.errback(GenericError("Bang"))
# *Then* build the DeferredList, with fireOnOneErrback=True
dl = DeferredList([d1, d2], fireOnOneErrback=True)
result: List[Failure] = []
dl.addErrback(result.append)
self.assertEqual(1, len(result))
d1.addErrback(lambda e: None) # Swallow error
def testDeferredListWithAlreadyFiredDeferreds(self) -> None:
# Create some deferreds, and err one, call the other
d1: Deferred[int] = Deferred()
d2: Deferred[int] = Deferred()
d1.errback(GenericError("Bang"))
d2.callback(2)
# *Then* build the DeferredList
dl = DeferredList([d1, d2])
result: List[List[Tuple[bool, int]]] = []
dl.addCallback(result.append)
self.assertEqual(1, len(result))
d1.addErrback(lambda e: None) # Swallow error
def test_cancelDeferredList(self) -> None:
"""
When cancelling an unfired L{DeferredList}, cancel every
L{Deferred} in the list.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo])
deferredList.cancel()
self.failureResultOf(deferredOne, defer.CancelledError)
self.failureResultOf(deferredTwo, defer.CancelledError)
def test_cancelDeferredListCallback(self) -> None:
"""
When cancelling an unfired L{DeferredList} without the
C{fireOnOneCallback} and C{fireOnOneErrback} flags set, the
L{DeferredList} will be callback with a C{list} of
(success, result) C{tuple}s.
"""
deferredOne: Deferred[str] = Deferred(fakeCallbackCanceller)
deferredTwo: Deferred[str] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo])
deferredList.cancel()
self.failureResultOf(deferredTwo, defer.CancelledError)
result = self.successResultOf(deferredList)
self.assertTrue(result[0][0])
self.assertEqual(result[0][1], "Callback Result")
self.assertFalse(result[1][0])
self.assertTrue(result[1][1].check(defer.CancelledError)) # type: ignore[attr-defined]
def test_cancelDeferredListWithFireOnOneCallback(self) -> None:
"""
When cancelling an unfired L{DeferredList} with the flag
C{fireOnOneCallback} set, cancel every L{Deferred} in the list.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo], fireOnOneCallback=True)
deferredList.cancel()
self.failureResultOf(deferredOne, defer.CancelledError)
self.failureResultOf(deferredTwo, defer.CancelledError)
def test_cancelDeferredListWithFireOnOneCallbackAndDeferredCallback(self) -> None:
"""
When cancelling an unfired L{DeferredList} with the flag
C{fireOnOneCallback} set, if one of the L{Deferred} callbacks
in its canceller, the L{DeferredList} will callback with the
result and the index of the L{Deferred} in a C{tuple}.
"""
deferredOne: Deferred[str] = Deferred(fakeCallbackCanceller)
deferredTwo: Deferred[str] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo], fireOnOneCallback=True)
deferredList.cancel()
self.failureResultOf(deferredTwo, defer.CancelledError)
result = self.successResultOf(deferredList)
self.assertEqual(result, ("Callback Result", 0))
def test_cancelDeferredListWithFireOnOneErrback(self) -> None:
"""
When cancelling an unfired L{DeferredList} with the flag
C{fireOnOneErrback} set, cancel every L{Deferred} in the list.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo], fireOnOneErrback=True)
deferredList.cancel()
self.failureResultOf(deferredOne, defer.CancelledError)
self.failureResultOf(deferredTwo, defer.CancelledError)
deferredListFailure = self.failureResultOf(deferredList, defer.FirstError)
firstError = deferredListFailure.value
self.assertTrue(firstError.subFailure.check(defer.CancelledError))
def test_cancelDeferredListWithFireOnOneErrbackAllDeferredsCallback(self) -> None:
"""
When cancelling an unfired L{DeferredList} with the flag
C{fireOnOneErrback} set, if all the L{Deferred} callbacks
in its canceller, the L{DeferredList} will callback with a
C{list} of (success, result) C{tuple}s.
"""
deferredOne: Deferred[str] = Deferred(fakeCallbackCanceller)
deferredTwo: Deferred[str] = Deferred(fakeCallbackCanceller)
deferredList = DeferredList([deferredOne, deferredTwo], fireOnOneErrback=True)
deferredList.cancel()
result = self.successResultOf(deferredList)
self.assertTrue(result[0][0])
self.assertEqual(result[0][1], "Callback Result")
self.assertTrue(result[1][0])
self.assertEqual(result[1][1], "Callback Result")
def test_cancelDeferredListWithOriginalDeferreds(self) -> None:
"""
Cancelling a L{DeferredList} will cancel the original
L{Deferred}s passed in.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
argumentList = [deferredOne, deferredTwo]
deferredList = DeferredList(argumentList)
deferredThree: Deferred[None] = Deferred()
argumentList.append(deferredThree)
deferredList.cancel()
self.failureResultOf(deferredOne, defer.CancelledError)
self.failureResultOf(deferredTwo, defer.CancelledError)
self.assertNoResult(deferredThree)
def test_cancelDeferredListWithException(self) -> None:
"""
Cancelling a L{DeferredList} will cancel every L{Deferred}
in the list even exceptions raised from the C{cancel} method of the
L{Deferred}s.
"""
def cancellerRaisesException(deferred: Deferred[object]) -> None:
"""
A L{Deferred} canceller that raises an exception.
@param deferred: The cancelled L{Deferred}.
"""
raise RuntimeError("test")
deferredOne: Deferred[None] = Deferred(cancellerRaisesException)
deferredTwo: Deferred[None] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo])
deferredList.cancel()
self.failureResultOf(deferredTwo, defer.CancelledError)
errors = self.flushLoggedErrors(RuntimeError)
self.assertEqual(len(errors), 1)
def test_cancelFiredOnOneCallbackDeferredList(self) -> None:
"""
When a L{DeferredList} has fired because one L{Deferred} in
the list fired with a non-failure result, the cancellation will do
nothing instead of cancelling the rest of the L{Deferred}s.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo], fireOnOneCallback=True)
deferredOne.callback(None)
deferredList.cancel()
self.assertNoResult(deferredTwo)
def test_cancelFiredOnOneErrbackDeferredList(self) -> None:
"""
When a L{DeferredList} has fired because one L{Deferred} in
the list fired with a failure result, the cancellation will do
nothing instead of cancelling the rest of the L{Deferred}s.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
deferredList = DeferredList([deferredOne, deferredTwo], fireOnOneErrback=True)
deferredOne.errback(GenericError("test"))
deferredList.cancel()
self.assertNoResult(deferredTwo)
self.failureResultOf(deferredOne, GenericError)
self.failureResultOf(deferredList, defer.FirstError)
def testImmediateSuccess(self) -> None:
l: List[str] = []
d: Deferred[str] = defer.succeed("success")
d.addCallback(l.append)
self.assertEqual(l, ["success"])
def testImmediateFailure(self) -> None:
l: List[Failure] = []
d: Deferred[None] = defer.fail(GenericError("fail"))
d.addErrback(l.append)
self.assertEqual(str(l[0].value), "fail")
def testPausedFailure(self) -> None:
l: List[Failure] = []
d = defer.fail(GenericError("fail"))
d.pause()
d.addErrback(l.append)
self.assertEqual(l, [])
d.unpause()
self.assertEqual(str(l[0].value), "fail")
def testCallbackErrors(self) -> None:
l: List[Failure] = []
d: Deferred[int] = Deferred()
d.addCallback(lambda _: 1 // 0).addErrback(l.append)
d.callback(1)
self.assertIsInstance(l[0].value, ZeroDivisionError)
l = []
d2 = Deferred[int]()
d2.addCallback(lambda _: Failure(ZeroDivisionError())).addErrback(l.append)
d2.callback(1)
self.assertIsInstance(l[0].value, ZeroDivisionError)
def testUnpauseBeforeCallback(self) -> None:
d: Deferred[None] = Deferred()
d.pause()
d.addCallback(self._callback)
d.unpause()
def test_callbackReturnsDeferred(self) -> None:
"""
Callbacks passed to L{Deferred.addCallback} can return Deferreds and
the next callback will not be run until that Deferred fires.
"""
d1: Deferred[int] = Deferred()
d2: Deferred[int] = Deferred()
d2.pause()
d1.addCallback(lambda r: d2)
d1.addCallback(self._callback)
d1.callback(1)
self.assertIsNone(self.callbackResults, "Should not have been called yet.")
d2.callback(2)
self.assertIsNone(
self.callbackResults, "Still should not have been called yet."
)
d2.unpause()
self.assertIsNotNone(self.callbackResults, "Should have been called now")
assert self.callbackResults is not None, "make that legible to the type checker"
self.assertEquals(
self.callbackResults[0][0],
2,
"Result should have been from second deferred:{}".format(
self.callbackResults
),
)
def test_callbackMaybeReturnsFailure(self) -> None:
"""
Callbacks passed to addCallback may return Failures.
"""
d: Deferred[int] = Deferred()
shouldFail = False
rte = RuntimeError()
def maybeFail(result: int) -> Union[int, Failure]:
# testing the Union return annotation here
if shouldFail:
return Failure(rte)
else:
return result + 1
d.callback(6)
self.assertEqual(self.successResultOf(d.addCallback(maybeFail)), 7)
d = Deferred[int]()
shouldFail = True
d.callback(6)
self.assertIs(
self.failureResultOf(
# make sure mypy still considers us a Deferred[int] here
d.addCallback(maybeFail).addCallback(maybeFail),
RuntimeError,
).value,
rte,
)
def test_errbackReturnsDeferred(self) -> None:
"""
Errbacks passed to L{Deferred.addErrback} can return Deferreds just as
callbacks can.
"""
d: Deferred[int] = Deferred()
d2: Deferred[str] = Deferred()
resultValues = []
def asyncErrback(result: Failure) -> Deferred[str]:
return d2
def syncCallback(result: Union[str, int]) -> None:
resultValues.append(result)
d.addErrback(asyncErrback).addCallback(syncCallback)
d.errback(ValueError())
self.assertNoResult(d)
self.assertEqual(resultValues, [])
d2.callback("result")
self.assertEqual(resultValues, ["result"])
def test_chainedPausedDeferredWithResult(self) -> None:
"""
When a paused Deferred with a result is returned from a callback on
another Deferred, the other Deferred is chained to the first and waits
for it to be unpaused.
"""
expected = object()
paused: Deferred[object] = Deferred()
paused.callback(expected)
paused.pause()
chained: Deferred[None] = Deferred()
chained.addCallback(lambda ignored: paused)
chained.callback(None)
result: List[object] = []
chained.addCallback(result.append)
self.assertEqual(result, [])
paused.unpause()
self.assertEqual(result, [expected])
def test_pausedDeferredChained(self) -> None:
"""
A paused Deferred encountered while pushing a result forward through a
chain does not prevent earlier Deferreds from continuing to execute
their callbacks.
"""
first: Deferred[None] = Deferred()
second: Deferred[None] = Deferred()
first.addCallback(lambda ignored: second)
first.callback(None)
first.pause()
second.callback(None)
result: List[None] = []
second.addCallback(result.append)
self.assertEqual(result, [None])
def test_gatherResults(self) -> None:
# test successful list of deferreds
results: List[List[int]] = []
defer.gatherResults([defer.succeed(1), defer.succeed(2)]).addCallback(
results.append
)
self.assertEqual(results, [[1, 2]])
# test failing list of deferreds
errors: List[Failure] = []
dl = [defer.succeed(1), defer.fail(ValueError())]
defer.gatherResults(dl).addErrback(errors.append)
self.assertEqual(len(errors), 1)
self.assertIsInstance(errors[0], Failure)
# get rid of error
dl[1].addErrback(lambda e: 1)
def test_gatherResultsWithConsumeErrors(self) -> None:
"""
If a L{Deferred} in the list passed to L{gatherResults} fires with a
failure and C{consumerErrors} is C{True}, the failure is converted to a
L{None} result on that L{Deferred}.
"""
# test successful list of deferreds
dgood = defer.succeed(1)
dbad = defer.fail(RuntimeError("oh noes"))
d = defer.gatherResults([dgood, dbad], consumeErrors=True)
unconsumedErrors: List[Failure] = []
dbad.addErrback(unconsumedErrors.append)
gatheredErrors: List[Failure] = []
d.addErrback(gatheredErrors.append)
self.assertEqual((len(unconsumedErrors), len(gatheredErrors)), (0, 1))
self.assertIsInstance(gatheredErrors[0].value, defer.FirstError)
firstError = gatheredErrors[0].value.subFailure
self.assertIsInstance(firstError.value, RuntimeError)
def test_cancelGatherResults(self) -> None:
"""
When cancelling the L{defer.gatherResults} call, all the
L{Deferred}s in the list will be cancelled.
"""
deferredOne: Deferred[None] = Deferred()
deferredTwo: Deferred[None] = Deferred()
result = defer.gatherResults([deferredOne, deferredTwo])
result.cancel()
self.failureResultOf(deferredOne, defer.CancelledError)
self.failureResultOf(deferredTwo, defer.CancelledError)
gatherResultsFailure = self.failureResultOf(result, defer.FirstError)
firstError = gatherResultsFailure.value
self.assertTrue(firstError.subFailure.check(defer.CancelledError))
def test_cancelGatherResultsWithAllDeferredsCallback(self) -> None:
"""
When cancelling the L{defer.gatherResults} call, if all the
L{Deferred}s callback in their canceller, the L{Deferred}
returned by L{defer.gatherResults} will be callbacked with the C{list}
of the results.
"""
deferredOne: Deferred[str] = Deferred(fakeCallbackCanceller)
deferredTwo: Deferred[str] = Deferred(fakeCallbackCanceller)
result = defer.gatherResults([deferredOne, deferredTwo])
result.cancel()
callbackResult = self.successResultOf(result)
self.assertEqual(callbackResult[0], "Callback Result")
self.assertEqual(callbackResult[1], "Callback Result")
def test_maybeDeferredSync(self) -> None:
"""
L{defer.maybeDeferred} should retrieve the result of a synchronous
function and pass it to its resulting L{Deferred}.
"""
result = object()
results: List[object] = []
errors: List[Failure] = []
d = defer.maybeDeferred(lambda: result)
d.addCallbacks(results.append, errors.append)
self.assertEqual(errors, [])
self.assertEqual(len(results), 1)
self.assertIdentical(results[0], result)
def test_maybeDeferredSyncWithArgs(self) -> None:
"""
L{defer.maybeDeferred} should pass arguments to the called function.
"""
def plusFive(x: int) -> int:
return x + 5
results: List[int] = []
errors: List[Failure] = []
d = defer.maybeDeferred(plusFive, 10)
assert_type(d, Deferred[int])
d.addCallbacks(results.append, errors.append)
self.assertEqual(errors, [])
self.assertEqual(results, [15])
def test_maybeDeferredSyncException(self) -> None:
"""
L{defer.maybeDeferred} should catch an exception raised by a synchronous
function and errback its resulting L{Deferred} with it.
"""
expected = ValueError("that value is unacceptable")
def raisesException() -> NoReturn:
raise expected
results: List[int] = []
errors: List[Failure] = []
defer.maybeDeferred(raisesException).addCallbacks(results.append, errors.append)
self.assertEqual(results, [])
self.assertEqual(len(errors), 1)
self.assertEqual(str(errors[0].value), str(expected))
def test_maybeDeferredSyncFailure(self) -> None:
"""
L{defer.maybeDeferred} should handle a L{Failure} returned by a
function and errback with it.
"""
try:
"10" + 5 # type: ignore[operator]
except TypeError:
expected = Failure()
results: List[int] = []
errors: List[Failure] = []
d = defer.maybeDeferred(lambda: expected)
d.addCallbacks(results.append, errors.append)
self.assertEqual(results, [])
self.assertEqual(len(errors), 1)
self.assertIdentical(errors[0], expected)
def test_maybeDeferredAsync(self) -> None:
"""
L{defer.maybeDeferred} should let L{Deferred} instance pass by
so that original result is the same.
"""
d1: Deferred[str] = Deferred()
d2 = defer.maybeDeferred(lambda: d1)
d1.callback("Success")
result: List[str] = []
d2.addCallback(result.append)
self.assertEqual(result, ["Success"])
def test_maybeDeferredAsyncError(self) -> None:
"""
L{defer.maybeDeferred} should let L{Deferred} instance pass by
so that L{Failure} returned by the original instance is the
same.
"""
d1: Deferred[None] = Deferred()
d2: Deferred[None] = defer.maybeDeferred(lambda: d1)
d1.errback(Failure(RuntimeError()))
self.assertImmediateFailure(d2, RuntimeError)
def test_maybeDeferredCoroutineSuccess(self) -> None:
"""
When called with a coroutine function L{defer.maybeDeferred} returns a
L{defer.Deferred} which has the same result as the coroutine returned
by the function.
"""
async def f() -> int:
return 7
coroutineDeferred = defer.maybeDeferred(f)
assert_type(coroutineDeferred, Deferred[int])
self.assertEqual(self.successResultOf(coroutineDeferred), 7)
def test_maybeDeferredCoroutineSuccessIndirect(self) -> None:
"""
When called with a coroutine function L{defer.maybeDeferred} returns a
L{defer.Deferred} which has the same result as the coroutine returned
by the function.
"""
async def f() -> int:
return 7
# Demonstrate that the function itself does not need to be a coroutine
# function to trigger the coroutine-handling behavior.
def g() -> Coroutine[Deferred[int], Any, Any]:
return f()
# Provide a simple callback mainly to ensure the type-checking on
# maybeDeferred is correct.
def typedCallback(result: int) -> int:
return result + 1
coroutineDeferred = defer.maybeDeferred(g)
assert_type(coroutineDeferred, Deferred[Any])
modifiedDeferred = coroutineDeferred.addCallback(typedCallback)
self.assertEqual(self.successResultOf(modifiedDeferred), 8)
def test_maybeDeferredCoroutineFailure(self) -> None:
"""
When called with a coroutine function L{defer.maybeDeferred} returns a
L{defer.Deferred} which has a L{Failure} result wrapping the exception
raised by the coroutine function.
"""
class SomeException(Exception):
pass
async def f() -> None:
raise SomeException()
# Demonstrate that the function itself does not need to be a coroutine
# function to trigger the coroutine-handling behavior.
def g() -> Coroutine[None, None, None]:
return f()
assert_that(
self.failureResultOf(defer.maybeDeferred(g)).type,
equal_to(SomeException),
)
def test_innerCallbacksPreserved(self) -> None:
"""
When a L{Deferred} encounters a result which is another L{Deferred}
which is waiting on a third L{Deferred}, the middle L{Deferred}'s
callbacks are executed after the third L{Deferred} fires and before the
first receives a result.
"""
results: List[Union[Tuple[str, str], str]] = []
failures: List[Failure] = []
inner: Deferred[str] = Deferred()
def cb(result: str) -> Deferred[str]:
results.append(("start-of-cb", result))
d = defer.succeed("inner")
def firstCallback(result: str) -> Deferred[str]:
results.append(("firstCallback", "inner"))
return inner
def secondCallback(result: str) -> str:
results.append(("secondCallback", result))
return result * 2
d.addCallback(firstCallback).addCallback(secondCallback)
d.addErrback(failures.append)
return d
outer = defer.succeed("outer")
outer.addCallback(cb)
inner.callback("orange")
outer.addCallback(results.append)
inner.addErrback(failures.append)
outer.addErrback(failures.append)
self.assertEqual([], failures)
self.assertEqual(
results,
[
("start-of-cb", "outer"),
("firstCallback", "inner"),
("secondCallback", "orange"),
"orangeorange",
],
)
def test_continueCallbackNotFirst(self) -> None:
"""
The continue callback of a L{Deferred} waiting for another L{Deferred}
is not necessarily the first one. This is somewhat a whitebox test
checking that we search for that callback among the whole list of
callbacks.
"""
results: List[Tuple[str, Union[str, List[str], None]]] = []
failures: List[Failure] = []
a: Deferred[str] = Deferred()
def cb(result: str) -> Deferred[None]:
results.append(("cb", result))
d: Deferred[None] = Deferred()
def firstCallback(result: None) -> Deferred[List[str]]:
results.append(("firstCallback", result))
return defer.gatherResults([a])
def secondCallback(result: List[str]) -> None:
results.append(("secondCallback", result))
returner = (
d.addCallback(firstCallback)
.addCallback(secondCallback)
.addErrback(failures.append)
)
d.callback(None)
return returner
defer.succeed("outer").addCallback(cb).addErrback(failures.append)
self.assertEqual([("cb", "outer"), ("firstCallback", None)], results)
a.callback("withers")
self.assertEqual([], failures)
self.assertEqual(
results,
[("cb", "outer"), ("firstCallback", None), ("secondCallback", ["withers"])],
)
def test_callbackOrderPreserved(self) -> None:
"""
A callback added to a L{Deferred} after a previous callback attached
another L{Deferred} as a result is run after the callbacks of the other
L{Deferred} are run.
"""
results: List[Tuple[str, Union[str, List[str], None]]] = []
failures: List[Failure] = []
a: Deferred[str] = Deferred()
def cb(result: str) -> Deferred[None]:
results.append(("cb", result))
d: Deferred[None] = Deferred()
def firstCallback(result: None) -> Deferred[List[str]]:
results.append(("firstCallback", result))
return defer.gatherResults([a])
def secondCallback(result: List[str]) -> None:
results.append(("secondCallback", result))
returner = (
d.addCallback(firstCallback)
.addCallback(secondCallback)
.addErrback(failures.append)
)
d.callback(None)
return returner
outer: Deferred[str] = Deferred()
outer.addCallback(cb)
outer.addCallback(lambda x: results.append(("final", None)))
outer.addErrback(failures.append)
outer.callback("outer")
self.assertEqual([("cb", "outer"), ("firstCallback", None)], results)
a.callback("withers")
self.assertEqual([], failures)
self.assertEqual(
results,
[
("cb", "outer"),
("firstCallback", None),
("secondCallback", ["withers"]),
("final", None),
],
)
def test_reentrantRunCallbacks(self) -> None:
"""
A callback added to a L{Deferred} by a callback on that L{Deferred}
should be added to the end of the callback chain.
"""
deferred: Deferred[None] = Deferred()
called = []
def callback3(result: None) -> None:
called.append(3)
def callback2(result: None) -> None:
called.append(2)
def callback1(result: None) -> None:
called.append(1)
deferred.addCallback(callback3)
deferred.addCallback(callback1)
deferred.addCallback(callback2)
deferred.callback(None)
self.assertEqual(called, [1, 2, 3])
def test_nonReentrantCallbacks(self) -> None:
"""
A callback added to a L{Deferred} by a callback on that L{Deferred}
should not be executed until the running callback returns.
"""
deferred: Deferred[None] = Deferred()
called = []
def callback2(result: None) -> None:
called.append(2)
def callback1(result: None) -> None:
called.append(1)
deferred.addCallback(callback2)
self.assertEqual(called, [1])
deferred.addCallback(callback1)
deferred.callback(None)
self.assertEqual(called, [1, 2])
def test_reentrantRunCallbacksWithFailure(self) -> None:
"""
After an exception is raised by a callback which was added to a
L{Deferred} by a callback on that L{Deferred}, the L{Deferred} should
call the first errback with a L{Failure} wrapping that exception.
"""
exceptionMessage = "callback raised exception"
deferred: Deferred[None] = Deferred()
def callback2(result: object) -> None:
raise Exception(exceptionMessage)
def callback1(result: object) -> None:
deferred.addCallback(callback2)
deferred.addCallback(callback1)
deferred.callback(None)
exception = self.assertImmediateFailure(deferred, Exception)
self.assertEqual(exception.args, (exceptionMessage,))
def test_synchronousImplicitChain(self) -> None:
"""
If a first L{Deferred} with a result is returned from a callback on a
second L{Deferred}, the result of the second L{Deferred} becomes the
result of the first L{Deferred} and the result of the first L{Deferred}
becomes L{None}.
"""
result = object()
first = defer.succeed(result)
second: Deferred[None] = Deferred()
second.addCallback(lambda ign: first)
second.callback(None)
results: List[Optional[object]] = []
first.addCallback(results.append)
self.assertIsNone(results[0])
second.addCallback(results.append)
self.assertIs(results[1], result)
def test_asynchronousImplicitChain(self) -> None:
"""
If a first L{Deferred} without a result is returned from a callback on
a second L{Deferred}, the result of the second L{Deferred} becomes the
result of the first L{Deferred} as soon as the first L{Deferred} has
one and the result of the first L{Deferred} becomes L{None}.
"""
first: Deferred[object] = Deferred()
second: Deferred[object] = Deferred()
second.addCallback(lambda ign: first)
second.callback(None)
firstResult: List[object] = []
first.addCallback(firstResult.append)
secondResult: List[object] = []
second.addCallback(secondResult.append)
self.assertEqual(firstResult, [])
self.assertEqual(secondResult, [])
result = object()
first.callback(result)
self.assertEqual(firstResult, [None])
self.assertEqual(secondResult, [result])
def test_synchronousImplicitErrorChain(self) -> None:
"""
If a first L{Deferred} with a L{Failure} result is returned from a
callback on a second L{Deferred}, the first L{Deferred}'s result is
converted to L{None} and no unhandled error is logged when it is
garbage collected.
"""
first = defer.fail(RuntimeError("First Deferred's Failure"))
def cb(_: None, first: Deferred[None] = first) -> Deferred[None]:
return first
second: Deferred[None] = Deferred()
second.addCallback(cb)
second.callback(None)
firstResult: List[None] = []
first.addCallback(firstResult.append)
self.assertIsNone(firstResult[0])
self.assertImmediateFailure(second, RuntimeError)
def test_asynchronousImplicitErrorChain(self) -> None:
"""
Let C{a} and C{b} be two L{Deferred}s.
If C{a} has no result and is returned from a callback on C{b} then when
C{a} fails, C{b}'s result becomes the L{Failure} that was C{a}'s result,
the result of C{a} becomes L{None} so that no unhandled error is logged
when it is garbage collected.
"""
first: Deferred[None] = Deferred()
second: Deferred[None] = Deferred()
second.addCallback(lambda ign: first)
second.callback(None)
secondError: List[Failure] = []
second.addErrback(secondError.append)
firstResult: List[None] = []
first.addCallback(firstResult.append)
secondResult: List[None] = []
second.addCallback(secondResult.append)
self.assertEqual(firstResult, [])
self.assertEqual(secondResult, [])
first.errback(RuntimeError("First Deferred's Failure"))
self.assertTrue(secondError[0].check(RuntimeError))
self.assertEqual(firstResult, [None])
self.assertEqual(len(secondResult), 1)
def test_doubleAsynchronousImplicitChaining(self) -> None:
"""
L{Deferred} chaining is transitive.
In other words, let A, B, and C be Deferreds. If C is returned from a
callback on B and B is returned from a callback on A then when C fires,
A fires.
"""
first: Deferred[object] = Deferred()
second: Deferred[object] = Deferred()
second.addCallback(lambda ign: first)
third: Deferred[object] = Deferred()
third.addCallback(lambda ign: second)
thirdResult: List[object] = []
third.addCallback(thirdResult.append)
result = object()
# After this, second is waiting for first to tell it to continue.
second.callback(None)
# And after this, third is waiting for second to tell it to continue.
third.callback(None)
# Still waiting
self.assertEqual(thirdResult, [])
# This will tell second to continue which will tell third to continue.
first.callback(result)
self.assertEqual(thirdResult, [result])
def test_nestedAsynchronousChainedDeferreds(self) -> None:
"""
L{Deferred}s can have callbacks that themselves return L{Deferred}s.
When these "inner" L{Deferred}s fire (even asynchronously), the
callback chain continues.
"""
results: List[Union[Tuple[str, str], str]] = []
failures: List[Failure] = []
# A Deferred returned in the inner callback.
inner: Deferred[str] = Deferred()
def cb(result: str) -> Deferred[str]:
results.append(("start-of-cb", result))
d = defer.succeed("inner")
def firstCallback(result: str) -> Deferred[str]:
results.append(("firstCallback", "inner"))
# Return a Deferred that definitely has not fired yet, so we
# can fire the Deferreds out of order.
return inner
def secondCallback(result: str) -> str:
results.append(("secondCallback", result))
return result * 2
d.addCallback(firstCallback).addCallback(secondCallback)
d.addErrback(failures.append)
return d
# Create a synchronous Deferred that has a callback 'cb' that returns
# a Deferred 'd' that has fired but is now waiting on an unfired
# Deferred 'inner'.
outer: Deferred[None] = (
defer.succeed("outer").addCallback(cb).addCallback(results.append)
)
# At this point, the callback 'cb' has been entered, and the first
# callback of 'd' has been called.
self.assertEqual(
results, [("start-of-cb", "outer"), ("firstCallback", "inner")]
)
# Once the inner Deferred is fired, processing of the outer Deferred's
# callback chain continues.
inner.callback("orange")
# Make sure there are no errors.
inner.addErrback(failures.append)
outer.addErrback(failures.append)
self.assertEqual([], failures, "Got errbacks but wasn't expecting any.")
self.assertEqual(
results,
[
("start-of-cb", "outer"),
("firstCallback", "inner"),
("secondCallback", "orange"),
"orangeorange",
],
)
def test_nestedAsynchronousChainedDeferredsWithExtraCallbacks(self) -> None:
"""
L{Deferred}s can have callbacks that themselves return L{Deferred}s.
These L{Deferred}s can have other callbacks added before they are
returned, which subtly changes the callback chain. When these "inner"
L{Deferred}s fire (even asynchronously), the outer callback chain
continues.
"""
results: List[Any] = []
failures: List[Failure] = []
# A Deferred returned in the inner callback after a callback is
# added explicitly and directly to it.
inner: Deferred[str] = Deferred()
def cb(result: str) -> Deferred[Optional[List[str]]]:
results.append(("start-of-cb", result))
d = defer.succeed("inner")
def firstCallback(result: str) -> Deferred[List[str]]:
results.append(("firstCallback", result))
# Return a Deferred that definitely has not fired yet with a
# result-transforming callback so we can fire the Deferreds
# out of order and see how the callback affects the ultimate
# results.
def transform(result: str) -> List[str]:
return [result]
return inner.addCallback(transform)
def secondCallback(result: List[str]) -> List[str]:
results.append(("secondCallback", result))
return result * 2
return (
d.addCallback(firstCallback)
.addCallback(secondCallback)
.addErrback(failures.append)
)
# Create a synchronous Deferred that has a callback 'cb' that returns
# a Deferred 'd' that has fired but is now waiting on an unfired
# Deferred 'inner'.
outer = defer.succeed("outer")
outer.addCallback(cb)
outer.addCallback(results.append)
# At this point, the callback 'cb' has been entered, and the first
# callback of 'd' has been called.
self.assertEqual(
results, [("start-of-cb", "outer"), ("firstCallback", "inner")]
)
# Once the inner Deferred is fired, processing of the outer Deferred's
# callback chain continues.
inner.callback("withers")
# Make sure there are no errors.
outer.addErrback(failures.append)
inner.addErrback(failures.append)
self.assertEqual([], failures, "Got errbacks but wasn't expecting any.")
self.assertEqual(
results,
[
("start-of-cb", "outer"),
("firstCallback", "inner"),
("secondCallback", ["withers"]),
["withers", "withers"],
],
)
def test_chainDeferredRecordsExplicitChain(self) -> None:
"""
When we chain a L{Deferred}, that chaining is recorded explicitly.
"""
a: Deferred[None] = Deferred()
b: Deferred[None] = Deferred()
b.chainDeferred(a)
self.assertIs(a._chainedTo, b)
def test_explicitChainClearedWhenResolved(self) -> None:
"""
Any recorded chaining is cleared once the chaining is resolved, since
it no longer exists.
In other words, if one L{Deferred} is recorded as depending on the
result of another, and I{that} L{Deferred} has fired, then the
dependency is resolved and we no longer benefit from recording it.
"""
a: Deferred[None] = Deferred()
b: Deferred[None] = Deferred()
b.chainDeferred(a)
b.callback(None)
self.assertIsNone(a._chainedTo)
def test_chainDeferredRecordsImplicitChain(self) -> None:
"""
We can chain L{Deferred}s implicitly by adding callbacks that return
L{Deferred}s. When this chaining happens, we record it explicitly as
soon as we can find out about it.
"""
a: Deferred[None] = Deferred()
b: Deferred[None] = Deferred()
a.addCallback(lambda ignored: b)
a.callback(None)
self.assertIs(a._chainedTo, b)
def test_circularChainWarning(self) -> None:
"""
When a Deferred is returned from a callback directly attached to that
same Deferred, a warning is emitted.
"""
d: Deferred[str] = Deferred()
def circularCallback(result: str) -> Deferred[str]:
return d
d.addCallback(circularCallback)
d.callback("foo")
circular_warnings = self.flushWarnings([circularCallback])
self.assertEqual(len(circular_warnings), 1)
warning = circular_warnings[0]
self.assertEqual(warning["category"], DeprecationWarning)
pattern = "Callback returned the Deferred it was attached to"
self.assertTrue(
re.search(pattern, warning["message"]),
"\nExpected match: {!r}\nGot: {!r}".format(pattern, warning["message"]),
)
def test_circularChainException(self) -> None:
"""
If the deprecation warning for circular deferred callbacks is
configured to be an error, the exception will become the failure
result of the Deferred.
"""
self.addCleanup(
setattr,
warnings,
"filters",
warnings.filters,
)
warnings.filterwarnings("error", category=DeprecationWarning)
d: Deferred[str] = Deferred()
def circularCallback(result: str) -> Deferred[str]:
return d
d.addCallback(circularCallback)
d.callback("foo")
failure = self.failureResultOf(d)
failure.trap(DeprecationWarning)
def test_repr(self) -> None:
"""
The C{repr()} of a L{Deferred} contains the class name and a
representation of the internal Python ID.
"""
d: Deferred[None] = Deferred()
address = id(d)
self.assertEqual(repr(d), f"<Deferred at 0x{address:x}>")
def test_reprWithResult(self) -> None:
"""
If a L{Deferred} has been fired, then its C{repr()} contains its
result.
"""
d: Deferred[str] = Deferred()
d.callback("orange")
self.assertEqual(repr(d), f"<Deferred at 0x{id(d):x} current result: 'orange'>")
def test_reprWithChaining(self) -> None:
"""
If a L{Deferred} C{a} has been fired, but is waiting on another
L{Deferred} C{b} that appears in its callback chain, then C{repr(a)}
says that it is waiting on C{b}.
"""
a: Deferred[None] = Deferred()
b: Deferred[None] = Deferred()
b.chainDeferred(a)
self.assertEqual(
repr(a),
f"<Deferred at 0x{id(a):x} waiting on Deferred at 0x{id(b):x}>",
)
def test_boundedStackDepth(self) -> None:
"""
The depth of the call stack does not grow as more L{Deferred} instances
are chained together.
"""
def chainDeferreds(howMany: int) -> int:
stack = []
def recordStackDepth(ignored: object) -> None:
stack.append(len(traceback.extract_stack()))
top: Deferred[None] = Deferred()
innerDeferreds: List[Deferred[None]] = [
Deferred() for ignored in range(howMany)
]
originalInners = innerDeferreds[:]
last: Deferred[None] = Deferred()
inner = innerDeferreds.pop()
def cbInner(
ignored: object, inner: Deferred[None] = inner
) -> Deferred[None]:
return inner
top.addCallback(cbInner)
top.addCallback(recordStackDepth)
while innerDeferreds:
newInner = innerDeferreds.pop()
def cbNewInner(
ignored: object, inner: Deferred[None] = newInner
) -> Deferred[None]:
return inner
inner.addCallback(cbNewInner)
inner = newInner
inner.addCallback(lambda ign: last)
top.callback(None)
for inner in originalInners:
inner.callback(None)
# Sanity check - the record callback is not intended to have
# fired yet.
self.assertEqual(stack, [])
# Now fire the last thing and return the stack depth at which the
# callback was invoked.
last.callback(None)
return stack[0]
# Callbacks should be invoked at the same stack depth regardless of
# how many Deferreds are chained.
self.assertEqual(chainDeferreds(1), chainDeferreds(2))
def test_resultOfDeferredResultOfDeferredOfFiredDeferredCalled(self) -> None:
"""
Given three Deferreds, one chained to the next chained to the next,
callbacks on the middle Deferred which are added after the chain is
created are called once the last Deferred fires.
This is more of a regression-style test. It doesn't exercise any
particular code path through the current implementation of Deferred, but
it does exercise a broken codepath through one of the variations of the
implementation proposed as a resolution to ticket #411.
"""
first: Deferred[None] = Deferred()
second: Deferred[None] = Deferred()
third: Deferred[None] = Deferred()
first.addCallback(lambda ignored: second)
second.addCallback(lambda ignored: third)
second.callback(None)
first.callback(None)
third.callback(None)
results: List[None] = []
second.addCallback(results.append)
self.assertEqual(results, [None])
def test_errbackWithNoArgsNoDebug(self) -> None:
"""
C{Deferred.errback()} creates a failure from the current Python
exception. When Deferred.debug is not set no globals or locals are
captured in that failure.
"""
defer.setDebugging(False)
d: Deferred[None] = Deferred()
l: List[Failure] = []
exc = GenericError("Bang")
try:
raise exc
except BaseException:
d.errback()
d.addErrback(l.append)
fail = l[0]
self.assertEqual(fail.value, exc)
localz, globalz = fail.frames[0][-2:]
self.assertEqual([], localz)
self.assertEqual([], globalz)
def test_errbackWithNoArgs(self) -> None:
"""
C{Deferred.errback()} creates a failure from the current Python
exception. When Deferred.debug is set globals and locals are captured
in that failure.
"""
defer.setDebugging(True)
d: Deferred[None] = Deferred()
l: List[Failure] = []
exc = GenericError("Bang")
try:
raise exc
except BaseException:
d.errback()
d.addErrback(l.append)
fail = l[0]
self.assertEqual(fail.value, exc)
localz, globalz = fail.frames[0][-2:]
self.assertNotEqual([], localz)
self.assertNotEqual([], globalz)
def test_errorInCallbackDoesNotCaptureVars(self) -> None:
"""
An error raised by a callback creates a Failure. The Failure captures
locals and globals if and only if C{Deferred.debug} is set.
"""
d: Deferred[None] = Deferred()
d.callback(None)
defer.setDebugging(False)
def raiseError(ignored: object) -> None:
raise GenericError("Bang")
d.addCallback(raiseError)
l: List[Failure] = []
d.addErrback(l.append)
fail = l[0]
localz, globalz = fail.frames[0][-2:]
self.assertEqual([], localz)
self.assertEqual([], globalz)
def test_errorInCallbackCapturesVarsWhenDebugging(self) -> None:
"""
An error raised by a callback creates a Failure. The Failure captures
locals and globals if and only if C{Deferred.debug} is set.
"""
d: Deferred[None] = Deferred()
d.callback(None)
defer.setDebugging(True)
def raiseError(ignored: object) -> None:
raise GenericError("Bang")
d.addCallback(raiseError)
l: List[Failure] = []
d.addErrback(l.append)
fail = l[0]
localz, globalz = fail.frames[0][-2:]
self.assertNotEqual([], localz)
self.assertNotEqual([], globalz)
def test_inlineCallbacksTracebacks(self) -> None:
"""
L{defer.inlineCallbacks} that re-raise tracebacks into their deferred
should not lose their tracebacks.
"""
f = getDivisionFailure()
d: Deferred[None] = Deferred()
try:
f.raiseException()
except BaseException:
d.errback()
def ic(d: object) -> Generator[Any, Any, None]: # pragma: no cover
"""
This is never called.
It is only used as the decorated function.
The resulting function is never called in this test.
This is used to make sure that if we wrap
an already failed deferred, inlineCallbacks
will not add any extra traceback frames.
"""
yield d
defer.inlineCallbacks(ic)
newFailure = self.failureResultOf(d)
tb = traceback.extract_tb(newFailure.getTracebackObject())
self.assertEqual(len(tb), 3)
self.assertIn("test_defer", tb[2][0])
self.assertEqual("getDivisionFailure", tb[2][2])
self.assertEqual("1 / 0", tb[2][3])
self.assertIn("test_defer", tb[0][0])
self.assertEqual("test_inlineCallbacksTracebacks", tb[0][2])
self.assertEqual("f.raiseException()", tb[0][3])
def test_fromCoroutine(self) -> None:
"""
It can discover the return type of a first level coroutine.
"""
async def returnsInt() -> int:
return 1
d = Deferred.fromCoroutine(returnsInt())
assert_type(d, Deferred[int])
self.assertEqual(1, self.successResultOf(d))
def test_fromCoroutineRequiresCoroutine(self) -> None:
"""
L{Deferred.fromCoroutine} requires a coroutine object or a generator,
and will reject things that are not that.
"""
thingsThatAreNotCoroutines = [
# Lambda
lambda x: x,
# Int
1,
# Boolean
True,
# Function
self.test_fromCoroutineRequiresCoroutine,
# None
None,
# Module
defer,
]
for thing in thingsThatAreNotCoroutines:
self.assertRaises(defer.NotACoroutineError, Deferred.fromCoroutine, thing)
@pyunit.skipIf(_PYPY, "GC works differently on PyPy.")
def test_canceller_circular_reference_callback(self) -> None:
"""
A circular reference between a `Deferred` and its canceller
is broken when the deferred is called.
"""
# Create a canceller and weak reference to track if its been freed.
canceller = DummyCanceller()
weakCanceller = weakref.ref(canceller)
# Create a Deferred with the above canceller, adding a reference to the
# deferred to the canceller to create the circular reference.
deferred: Deferred[Any] = Deferred(canceller)
canceller.deferred = deferred
weakDeferred = weakref.ref(deferred)
deferred.callback(None)
# We manually remove the reference from the local
# function scope, to avoid interfering with the test.
del deferred
del canceller
# Once all local references have been dropped, the canceller should have
# been freed.
self.assertIsNone(weakCanceller())
self.assertIsNone(weakDeferred())
@pyunit.skipIf(_PYPY, "GC works differently on PyPy.")
def test_canceller_circular_reference_errback(self) -> None:
"""
A circular reference between a `Deferred` and its canceller
is broken when the deferred fails.
"""
# Create a canceller and weak reference to track if its been freed.
canceller = DummyCanceller()
weakCanceller = weakref.ref(canceller)
# Create a Deferred with the above canceller, adding a reference to the
# deferred to the canceller to create the circular reference.
deferred: Deferred[Any] = Deferred(canceller)
canceller.deferred = deferred
weakDeferred = weakref.ref(deferred)
failure = Failure(Exception("The test demands failures."))
deferred.errback(failure)
# We need to get the failure out of the deferred otherwise the test will
# fail due to unhandled error.
self.failureResultOf(deferred)
del deferred
del canceller
# Once all local references have been dropped, the canceller should have
# been freed.
self.assertIsNone(weakCanceller())
self.assertIsNone(weakDeferred())
@pyunit.skipIf(_PYPY, "GC works differently on PyPy.")
def test_canceller_circular_reference_non_final(self) -> None:
"""
A circular reference between a `Deferred` and its canceller is broken
when the deferred is called, even if another deferred gets added to its
chain.
"""
# Create a canceller and weak reference to track if its been freed.
canceller = DummyCanceller()
weakCanceller = weakref.ref(canceller)
# Create a Deferred with the above canceller, adding a reference to the
# deferred to the canceller to create the circular reference.
deferred: Deferred[Any] = Deferred(canceller)
canceller.deferred = deferred
deferred.addCallback(lambda _: Deferred())
deferred.callback(None)
del deferred
del canceller
# Once all local references have been dropped, the canceller should have
# been freed.
self.assertIsNone(weakCanceller())
class DummyCanceller:
"""
A callable that does nothing.
It is intended to be used just to get an object reference
to support GC related tests.
"""
deferred: Optional[Deferred[Any]] = None
def __call__(self, deferred: Deferred[Any]) -> None: # pragma: no cover
"""
This is not expected to be called as part of the current test suite.
"""
def _setupRaceState(numDeferreds: int) -> tuple[list[int], list[Deferred[object]]]:
"""
Create a list of Deferreds and a corresponding list of integers
tracking how many times each Deferred has been cancelled. Without
additional steps the Deferreds will never fire.
"""
cancelledState = [0] * numDeferreds
ds: list[Deferred[object]] = []
for n in range(numDeferreds):
def cancel(d: Deferred[object], n: int = n) -> None:
cancelledState[n] += 1
ds.append(Deferred(canceller=cancel))
return cancelledState, ds
class RaceTests(unittest.SynchronousTestCase):
"""
Tests for L{race}.
"""
@given(
beforeWinner=integers(min_value=0, max_value=3),
afterWinner=integers(min_value=0, max_value=3),
)
def test_success(self, beforeWinner: int, afterWinner: int) -> None:
"""
When one of the L{Deferred}s passed to L{race} fires successfully,
the L{Deferred} return by L{race} fires with the index of that
L{Deferred} and its result and cancels the rest of the L{Deferred}s.
@param beforeWinner: A randomly selected number of Deferreds to
appear before the "winning" Deferred in the list passed in.
@param beforeWinner: A randomly selected number of Deferreds to
appear after the "winning" Deferred in the list passed in.
"""
cancelledState, ds = _setupRaceState(beforeWinner + 1 + afterWinner)
raceResult = race(ds)
expected = object()
ds[beforeWinner].callback(expected)
# The result should be the index and result of the only Deferred that
# fired.
assert_that(
self.successResultOf(raceResult),
equal_to((beforeWinner, expected)),
)
# All Deferreds except the winner should have been cancelled once.
expectedCancelledState = [1] * beforeWinner + [0] + [1] * afterWinner
assert_that(
cancelledState,
equal_to(expectedCancelledState),
)
@given(
beforeWinner=integers(min_value=0, max_value=3),
afterWinner=integers(min_value=0, max_value=3),
)
def test_failure(self, beforeWinner: int, afterWinner: int) -> None:
"""
When all of the L{Deferred}s passed to L{race} fire with failures,
the L{Deferred} return by L{race} fires with L{FailureGroup} wrapping
all of their failures.
@param beforeWinner: A randomly selected number of Deferreds to
appear before the "winning" Deferred in the list passed in.
@param beforeWinner: A randomly selected number of Deferreds to
appear after the "winning" Deferred in the list passed in.
"""
cancelledState, ds = _setupRaceState(beforeWinner + 1 + afterWinner)
failure = Failure(Exception("The test demands failures."))
raceResult = race(ds)
for d in ds:
d.errback(failure)
actualFailure = self.failureResultOf(raceResult, FailureGroup)
assert_that(
actualFailure.value.failures,
equal_to([failure] * len(ds)),
)
assert_that(
cancelledState,
equal_to([0] * len(ds)),
)
@given(
beforeWinner=integers(min_value=0, max_value=3),
afterWinner=integers(min_value=0, max_value=3),
)
def test_resultAfterCancel(self, beforeWinner: int, afterWinner: int) -> None:
"""
If one of the Deferreds fires after it was cancelled its result
goes nowhere. In particular, it does not cause any errors to be
logged.
"""
# Ensure we have a Deferred to win and at least one other Deferred
# that can ignore cancellation.
ds: list[Deferred[None]] = [
Deferred() for n in range(beforeWinner + 2 + afterWinner)
]
raceResult = race(ds)
ds[beforeWinner].callback(None)
ds[beforeWinner + 1].callback(None)
self.successResultOf(raceResult)
assert_that(self.flushLoggedErrors(), empty())
def test_resultFromCancel(self) -> None:
"""
If one of the input Deferreds has a cancel function that fires it
with success, nothing bad happens.
"""
winner: Deferred[object] = Deferred()
ds: list[Deferred[object]] = [
winner,
Deferred(canceller=lambda d: d.callback(object())),
]
expected = object()
raceResult = race(ds)
winner.callback(expected)
assert_that(self.successResultOf(raceResult), equal_to((0, expected)))
@given(
numDeferreds=integers(min_value=1, max_value=3),
)
def test_cancel(self, numDeferreds: int) -> None:
"""
If the result of L{race} is cancelled then all of the L{Deferred}s
passed in are cancelled.
"""
cancelledState, ds = _setupRaceState(numDeferreds)
raceResult = race(ds)
raceResult.cancel()
assert_that(cancelledState, equal_to([1] * numDeferreds))
self.failureResultOf(raceResult, FailureGroup)
class FirstErrorTests(unittest.SynchronousTestCase):
"""
Tests for L{FirstError}.
"""
def test_repr(self) -> None:
"""
The repr of a L{FirstError} instance includes the repr of the value of
the sub-failure and the index which corresponds to the L{FirstError}.
"""
exc = ValueError("some text")
try:
raise exc
except BaseException:
f = Failure()
error = defer.FirstError(f, 3)
self.assertEqual(repr(error), f"FirstError[#3, {repr(exc)}]")
def test_str(self) -> None:
"""
The str of a L{FirstError} instance includes the str of the
sub-failure and the index which corresponds to the L{FirstError}.
"""
exc = ValueError("some text")
try:
raise exc
except BaseException:
f = Failure()
error = defer.FirstError(f, 5)
self.assertEqual(str(error), f"FirstError[#5, {str(f)}]")
def test_comparison(self) -> None:
"""
L{FirstError} instances compare equal to each other if and only if
their failure and index compare equal. L{FirstError} instances do not
compare equal to instances of other types.
"""
try:
1 // 0
except BaseException:
firstFailure = Failure()
one = defer.FirstError(firstFailure, 13)
anotherOne = defer.FirstError(firstFailure, 13)
try:
raise ValueError("bar")
except BaseException:
secondFailure = Failure()
another = defer.FirstError(secondFailure, 9)
self.assertTrue(one == anotherOne)
self.assertFalse(one == another)
self.assertTrue(one != another)
self.assertFalse(one != anotherOne)
self.assertFalse(one == 10)
class AlreadyCalledTests(unittest.SynchronousTestCase):
def setUp(self) -> None:
self._deferredWasDebugging = defer.getDebugging()
defer.setDebugging(True)
def tearDown(self) -> None:
defer.setDebugging(self._deferredWasDebugging)
def _callback(self, *args: object, **kwargs: object) -> None:
pass
def _errback(self, *args: object, **kwargs: object) -> None:
pass
def _call_1(self, d: Deferred[str]) -> None:
d.callback("hello")
def _call_2(self, d: Deferred[str]) -> None:
d.callback("twice")
def _err_1(self, d: Deferred[str]) -> None:
d.errback(Failure(RuntimeError()))
def _err_2(self, d: Deferred[str]) -> None:
d.errback(Failure(RuntimeError()))
def testAlreadyCalled_CC(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._call_1(d)
self.assertRaises(defer.AlreadyCalledError, self._call_2, d)
def testAlreadyCalled_CE(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._call_1(d)
self.assertRaises(defer.AlreadyCalledError, self._err_2, d)
def testAlreadyCalled_EE(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._err_1(d)
self.assertRaises(defer.AlreadyCalledError, self._err_2, d)
def testAlreadyCalled_EC(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._err_1(d)
self.assertRaises(defer.AlreadyCalledError, self._call_2, d)
def _count(self, linetype: str, func: str, lines: List[str], expected: int) -> None:
count = 0
for line in lines:
if line.startswith(" %s:" % linetype) and line.endswith(" %s" % func):
count += 1
self.assertTrue(count == expected)
def _check(self, e: Exception, caller: str, invoker1: str, invoker2: str) -> None:
# make sure the debugging information is vaguely correct
lines = e.args[0].split("\n")
# the creator should list the creator (testAlreadyCalledDebug) but not
# _call_1 or _call_2 or other invokers
self._count("C", caller, lines, 1)
self._count("C", "_call_1", lines, 0)
self._count("C", "_call_2", lines, 0)
self._count("C", "_err_1", lines, 0)
self._count("C", "_err_2", lines, 0)
# invoker should list the first invoker but not the second
self._count("I", invoker1, lines, 1)
self._count("I", invoker2, lines, 0)
def testAlreadyCalledDebug_CC(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._call_1(d)
try:
self._call_2(d)
except defer.AlreadyCalledError as e:
self._check(e, "testAlreadyCalledDebug_CC", "_call_1", "_call_2")
else:
self.fail("second callback failed to raise AlreadyCalledError")
def testAlreadyCalledDebug_CE(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._call_1(d)
try:
self._err_2(d)
except defer.AlreadyCalledError as e:
self._check(e, "testAlreadyCalledDebug_CE", "_call_1", "_err_2")
else:
self.fail("second errback failed to raise AlreadyCalledError")
def testAlreadyCalledDebug_EC(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._err_1(d)
try:
self._call_2(d)
except defer.AlreadyCalledError as e:
self._check(e, "testAlreadyCalledDebug_EC", "_err_1", "_call_2")
else:
self.fail("second callback failed to raise AlreadyCalledError")
def testAlreadyCalledDebug_EE(self) -> None:
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._err_1(d)
try:
self._err_2(d)
except defer.AlreadyCalledError as e:
self._check(e, "testAlreadyCalledDebug_EE", "_err_1", "_err_2")
else:
self.fail("second errback failed to raise AlreadyCalledError")
def testNoDebugging(self) -> None:
defer.setDebugging(False)
d: Deferred[str] = Deferred()
d.addCallbacks(self._callback, self._errback)
self._call_1(d)
try:
self._call_2(d)
except defer.AlreadyCalledError as e:
self.assertFalse(e.args)
else:
self.fail("second callback failed to raise AlreadyCalledError")
def testSwitchDebugging(self) -> None:
# Make sure Deferreds can deal with debug state flipping
# around randomly. This is covering a particular fixed bug.
defer.setDebugging(False)
d: Deferred[None] = Deferred()
d.addBoth(lambda ign: None)
defer.setDebugging(True)
d.callback(None)
defer.setDebugging(False)
d = Deferred()
d.callback(None)
defer.setDebugging(True)
d.addBoth(lambda ign: None)
class DeferredCancellerTests(unittest.SynchronousTestCase):
def setUp(self) -> None:
self.callbackResults: Optional[str] = None
self.errbackResults: Optional[Failure] = None
self.callback2Results: Optional[str] = None
self.cancellerCallCount = 0
def tearDown(self) -> None:
# Sanity check that the canceller was called at most once.
self.assertIn(self.cancellerCallCount, (0, 1))
def _callback(self, data: str) -> str:
self.callbackResults = data
return data
def _callback2(self, data: str) -> None:
self.callback2Results = data
def _errback(self, error: Failure) -> None:
self.errbackResults = error
def test_noCanceller(self) -> None:
"""
A L{Deferred} without a canceller must errback with a
L{defer.CancelledError} and not callback.
"""
d: Deferred[None] = Deferred()
d.addCallbacks(self._callback, self._errback)
d.cancel()
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, defer.CancelledError)
self.assertIsNone(self.callbackResults)
def test_raisesAfterCancelAndCallback(self) -> None:
"""
A L{Deferred} without a canceller, when cancelled must allow
a single extra call to callback, and raise
L{defer.AlreadyCalledError} if callbacked or errbacked thereafter.
"""
d: Deferred[None] = Deferred()
d.addCallbacks(self._callback, self._errback)
d.cancel()
# A single extra callback should be swallowed.
d.callback(None)
# But a second call to callback or errback is not.
self.assertRaises(defer.AlreadyCalledError, d.callback, None)
self.assertRaises(defer.AlreadyCalledError, d.errback, Exception())
def test_raisesAfterCancelAndErrback(self) -> None:
"""
A L{Deferred} without a canceller, when cancelled must allow
a single extra call to errback, and raise
L{defer.AlreadyCalledError} if callbacked or errbacked thereafter.
"""
d: Deferred[None] = Deferred()
d.addCallbacks(self._callback, self._errback)
d.cancel()
# A single extra errback should be swallowed.
d.errback(Exception())
# But a second call to callback or errback is not.
self.assertRaises(defer.AlreadyCalledError, d.callback, None)
self.assertRaises(defer.AlreadyCalledError, d.errback, Exception())
def test_noCancellerMultipleCancelsAfterCancelAndCallback(self) -> None:
"""
A L{Deferred} without a canceller, when cancelled and then
callbacked, ignores multiple cancels thereafter.
"""
d: Deferred[None] = Deferred()
d.addCallbacks(self._callback, self._errback)
d.cancel()
currentFailure = self.errbackResults
# One callback will be ignored
d.callback(None)
# Cancel should have no effect.
d.cancel()
self.assertIs(currentFailure, self.errbackResults)
def test_noCancellerMultipleCancelsAfterCancelAndErrback(self) -> None:
"""
A L{Deferred} without a canceller, when cancelled and then
errbacked, ignores multiple cancels thereafter.
"""
d: Deferred[None] = Deferred()
d.addCallbacks(self._callback, self._errback)
d.cancel()
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, defer.CancelledError)
currentFailure = self.errbackResults
# One errback will be ignored
d.errback(GenericError())
# I.e., we should still have a CancelledError.
self.assertEqual(self.errbackResults.type, defer.CancelledError)
d.cancel()
self.assertIs(currentFailure, self.errbackResults)
def test_noCancellerMultipleCancel(self) -> None:
"""
Calling cancel multiple times on a deferred with no canceller
results in a L{defer.CancelledError}. Subsequent calls to cancel
do not cause an error.
"""
d: Deferred[None] = Deferred()
d.addCallbacks(self._callback, self._errback)
d.cancel()
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, defer.CancelledError)
currentFailure = self.errbackResults
d.cancel()
self.assertIs(currentFailure, self.errbackResults)
def test_cancellerMultipleCancel(self) -> None:
"""
Verify that calling cancel multiple times on a deferred with a
canceller that does not errback results in a
L{defer.CancelledError} and that subsequent calls to cancel do not
cause an error and that after all that, the canceller was only
called once.
"""
def cancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
d: Deferred[None] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.cancel()
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, defer.CancelledError)
currentFailure = self.errbackResults
d.cancel()
self.assertIs(currentFailure, self.errbackResults)
self.assertEqual(self.cancellerCallCount, 1)
def test_simpleCanceller(self) -> None:
"""
Verify that a L{Deferred} calls its specified canceller when
it is cancelled, and that further call/errbacks raise
L{defer.AlreadyCalledError}.
"""
def cancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
d: Deferred[None] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.cancel()
self.assertEqual(self.cancellerCallCount, 1)
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, defer.CancelledError)
# Test that further call/errbacks are *not* swallowed
self.assertRaises(defer.AlreadyCalledError, d.callback, None)
self.assertRaises(defer.AlreadyCalledError, d.errback, Exception())
def test_cancellerArg(self) -> None:
"""
Verify that a canceller is given the correct deferred argument.
"""
def cancel(d1: Deferred[object]) -> None:
self.assertIs(d1, d)
d: Deferred[None] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.cancel()
def test_cancelAfterCallback(self) -> None:
"""
Test that cancelling a deferred after it has been callbacked does
not cause an error.
"""
def cancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
d.errback(GenericError())
d: Deferred[str] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.callback("biff!")
d.cancel()
self.assertEqual(self.cancellerCallCount, 0)
self.assertIsNone(self.errbackResults)
self.assertEqual(self.callbackResults, "biff!")
def test_cancelAfterErrback(self) -> None:
"""
Test that cancelling a L{Deferred} after it has been errbacked does
not result in a L{defer.CancelledError}.
"""
def cancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
d.errback(GenericError())
d: Deferred[None] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.errback(GenericError())
d.cancel()
self.assertEqual(self.cancellerCallCount, 0)
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, GenericError)
self.assertIsNone(self.callbackResults)
def test_cancellerThatErrbacks(self) -> None:
"""
Test a canceller which errbacks its deferred.
"""
def cancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
d.errback(GenericError())
d: Deferred[None] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.cancel()
self.assertEqual(self.cancellerCallCount, 1)
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, GenericError)
def test_cancellerThatCallbacks(self) -> None:
"""
Test a canceller which calls its deferred.
"""
def cancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
d.callback("hello!")
d: Deferred[None] = Deferred(canceller=cancel)
d.addCallbacks(self._callback, self._errback)
d.cancel()
self.assertEqual(self.cancellerCallCount, 1)
self.assertEqual(self.callbackResults, "hello!")
self.assertIsNone(self.errbackResults)
def test_cancelNestedDeferred(self) -> None:
"""
Verify that a Deferred, a, which is waiting on another Deferred, b,
returned from one of its callbacks, will propagate
L{defer.CancelledError} when a is cancelled.
"""
def innerCancel(d: Deferred[object]) -> None:
self.cancellerCallCount += 1
def cancel(d: Deferred[object]) -> None:
self.assertTrue(False)
b: Deferred[None] = Deferred(canceller=innerCancel)
a: Deferred[None] = Deferred(canceller=cancel)
a.callback(None)
a.addCallback(lambda data: b)
a.cancel()
a.addCallbacks(self._callback, self._errback)
# The cancel count should be one (the cancellation done by B)
self.assertEqual(self.cancellerCallCount, 1)
# B's canceller didn't errback, so defer.py will have called errback
# with a CancelledError.
assert self.errbackResults is not None
self.assertEqual(self.errbackResults.type, defer.CancelledError)
class LogTests(unittest.SynchronousTestCase):
"""
Test logging of unhandled errors.
"""
def setUp(self) -> None:
"""
Add a custom observer to observer logging.
"""
self.c: List[Dict[str, Any]] = []
log.addObserver(self.c.append)
def tearDown(self) -> None:
"""
Remove the observer.
"""
log.removeObserver(self.c.append)
def _loggedErrors(self) -> List[Dict[str, Any]]:
return [e for e in self.c if e["isError"]]
def _check(self) -> None:
"""
Check the output of the log observer to see if the error is present.
"""
c2 = self._loggedErrors()
self.assertEqual(len(c2), 2)
c2[1]["failure"].trap(ZeroDivisionError)
self.flushLoggedErrors(ZeroDivisionError)
def test_errorLog(self) -> None:
"""
Verify that when a L{Deferred} with no references to it is fired,
and its final result (the one not handled by any callback) is an
exception, that exception will be logged immediately.
"""
Deferred().addCallback(lambda x: 1 // 0).callback(1)
gc.collect()
self._check()
def test_errorLogWithInnerFrameRef(self) -> None:
"""
Same as L{test_errorLog}, but with an inner frame.
"""
def _subErrorLogWithInnerFrameRef() -> None:
d: Deferred[int] = Deferred()
d.addCallback(lambda x: 1 // 0)
d.callback(1)
_subErrorLogWithInnerFrameRef()
gc.collect()
self._check()
def test_errorLogWithInnerFrameCycle(self) -> None:
"""
Same as L{test_errorLogWithInnerFrameRef}, plus create a cycle.
"""
def _subErrorLogWithInnerFrameCycle() -> None:
d: Deferred[int] = Deferred()
def unusedCycle(x: int, d: Deferred[int] = d) -> int:
return 1 // 0
d.addCallback(unusedCycle)
# Set a self deference on to create a cycle
d._d = d # type: ignore[attr-defined]
d.callback(1)
_subErrorLogWithInnerFrameCycle()
gc.collect()
self._check()
def test_errorLogNoRepr(self) -> None:
"""
Verify that when a L{Deferred} with no references to it is fired,
the logged message does not contain a repr of the failure object.
"""
Deferred().addCallback(lambda x: 1 // 0).callback(1)
gc.collect()
self._check()
self.assertEqual(2, len(self.c))
msg = log.textFromEventDict(self.c[-1])
assert msg is not None
expected = "Unhandled Error\nTraceback "
self.assertTrue(
msg.startswith(expected),
f"Expected message starting with: {expected!r}",
)
def test_errorLogDebugInfo(self) -> None:
"""
Verify that when a L{Deferred} with no references to it is fired,
the logged message includes debug info if debugging on the deferred
is enabled.
"""
def doit() -> None:
d: Deferred[int] = Deferred()
d.debug = True
d.addCallback(lambda x: 1 // 0)
d.callback(1)
doit()
gc.collect()
self._check()
self.assertEqual(2, len(self.c))
msg = log.textFromEventDict(self.c[-1])
assert msg is not None
expected = "(debug: I"
self.assertTrue(
msg.startswith(expected),
f"Expected message starting with: {expected!r}",
)
def test_chainedErrorCleanup(self) -> None:
"""
If one Deferred with an error result is returned from a callback on
another Deferred, when the first Deferred is garbage collected it does
not log its error.
"""
d: Deferred[None] = Deferred()
d.addCallback(lambda ign: defer.fail(RuntimeError("zoop")))
d.callback(None)
# Sanity check - this isn't too interesting, but we do want the original
# Deferred to have gotten the failure.
results: List[None] = []
errors: List[Failure] = []
d.addCallbacks(results.append, errors.append)
self.assertEqual(results, [])
self.assertEqual(len(errors), 1)
errors[0].trap(Exception)
# Get rid of any references we might have to the inner Deferred (none of
# these should really refer to it, but we're just being safe).
del results, errors, d
# Force a collection cycle so that there's a chance for an error to be
# logged, if it's going to be logged.
gc.collect()
# And make sure it is not.
self.assertEqual(self._loggedErrors(), [])
def test_errorClearedByChaining(self) -> None:
"""
If a Deferred with a failure result has an errback which chains it to
another Deferred, the initial failure is cleared by the errback so it is
not logged.
"""
# Start off with a Deferred with a failure for a result
bad: Optional[Deferred[None]] = defer.fail(Exception("oh no"))
good: Optional[Deferred[None]] = Deferred()
# Give it a callback that chains it to another Deferred
assert bad is not None
bad.addErrback(lambda ignored: good)
# That's all, clean it up. No Deferred here still has a failure result,
# so nothing should be logged.
good = bad = None
gc.collect()
self.assertEqual(self._loggedErrors(), [])
class DeferredListEmptyTests(unittest.SynchronousTestCase):
def setUp(self) -> None:
self.callbackRan = 0
def testDeferredListEmpty(self) -> None:
"""Testing empty DeferredList."""
dl: Deferred[_DeferredListResultListT[object]] = DeferredList([])
dl.addCallback(self.cb_empty)
def cb_empty(self, res: List[Tuple[bool, object]]) -> None:
self.callbackRan = 1
self.assertEqual([], res)
def tearDown(self) -> None:
self.assertTrue(self.callbackRan, "Callback was never run.")
class OtherPrimitivesTests(unittest.SynchronousTestCase, ImmediateFailureMixin):
def _incr(self, result: object) -> None:
self.counter += 1
def setUp(self) -> None:
self.counter = 0
def testLock(self) -> None:
lock = DeferredLock()
lock.acquire().addCallback(self._incr)
self.assertTrue(lock.locked)
self.assertEqual(self.counter, 1)
lock.acquire().addCallback(self._incr)
self.assertTrue(lock.locked)
self.assertEqual(self.counter, 1)
lock.release()
self.assertTrue(lock.locked)
self.assertEqual(self.counter, 2)
lock.release()
self.assertFalse(lock.locked)
self.assertEqual(self.counter, 2)
self.assertRaises(TypeError, lock.run)
firstUnique = object()
secondUnique = object()
controlDeferred: Deferred[object] = Deferred()
result: Optional[object] = None
def helper(resultValue: object, returnValue: object = None) -> object:
nonlocal result
result = resultValue
return returnValue
resultDeferred = lock.run(
helper, resultValue=firstUnique, returnValue=controlDeferred
)
self.assertTrue(lock.locked)
self.assertEqual(result, firstUnique)
resultDeferred.addCallback(helper)
lock.acquire().addCallback(self._incr)
self.assertTrue(lock.locked)
self.assertEqual(self.counter, 2)
controlDeferred.callback(secondUnique)
self.assertEqual(result, secondUnique)
self.assertTrue(lock.locked)
self.assertEqual(self.counter, 3)
d = lock.acquire().addBoth(helper)
d.cancel()
self.assertIsInstance(result, Failure)
self.assertEqual(cast(Failure, result).type, defer.CancelledError)
lock.release()
self.assertFalse(lock.locked)
def returnsInt() -> Deferred[int]:
return defer.succeed(2)
async def returnsCoroInt() -> int:
return 1
assert_type(lock.run(returnsInt), Deferred[int])
assert_type(lock.run(returnsCoroInt), Deferred[int])
def test_cancelLockAfterAcquired(self) -> None:
"""
When canceling a L{Deferred} from a L{DeferredLock} that already
has the lock, the cancel should have no effect.
"""
def failOnErrback(f: Failure) -> None:
self.fail("Unexpected errback call!")
lock = DeferredLock()
d = lock.acquire()
d.addErrback(failOnErrback)
d.cancel()
def test_cancelLockBeforeAcquired(self) -> None:
"""
When canceling a L{Deferred} from a L{DeferredLock} that does not
yet have the lock (i.e., the L{Deferred} has not fired), the cancel
should cause a L{defer.CancelledError} failure.
"""
lock = DeferredLock()
lock.acquire()
d = lock.acquire()
d.cancel()
self.assertImmediateFailure(d, defer.CancelledError)
def testSemaphore(self) -> None:
N = 13
sem = DeferredSemaphore(N)
controlDeferred: Deferred[None] = Deferred()
helperArg: object = None
def helper(arg: object) -> Deferred[None]:
nonlocal helperArg
helperArg = arg
return controlDeferred
results: List[object] = []
uniqueObject = object()
resultDeferred = sem.run(helper, arg=uniqueObject)
resultDeferred.addCallback(results.append)
resultDeferred.addCallback(self._incr)
self.assertEqual(results, [])
self.assertEqual(helperArg, uniqueObject)
controlDeferred.callback(None)
self.assertIsNone(results.pop())
self.assertEqual(self.counter, 1)
self.counter = 0
for i in range(1, 1 + N):
sem.acquire().addCallback(self._incr)
self.assertEqual(self.counter, i)
success = []
def fail(r: object) -> None:
success.append(False)
def succeed(r: object) -> None:
success.append(True)
d = sem.acquire().addCallbacks(fail, succeed)
d.cancel()
self.assertEqual(success, [True])
sem.acquire().addCallback(self._incr)
self.assertEqual(self.counter, N)
sem.release()
self.assertEqual(self.counter, N + 1)
for i in range(1, 1 + N):
sem.release()
self.assertEqual(self.counter, N + 1)
def test_semaphoreInvalidTokens(self) -> None:
"""
If the token count passed to L{DeferredSemaphore} is less than one
then L{ValueError} is raised.
"""
self.assertRaises(ValueError, DeferredSemaphore, 0)
self.assertRaises(ValueError, DeferredSemaphore, -1)
def test_cancelSemaphoreAfterAcquired(self) -> None:
"""
When canceling a L{Deferred} from a L{DeferredSemaphore} that
already has the semaphore, the cancel should have no effect.
"""
def failOnErrback(f: Failure) -> None:
self.fail("Unexpected errback call!")
sem = DeferredSemaphore(1)
d = sem.acquire()
d.addErrback(failOnErrback)
d.cancel()
def test_cancelSemaphoreBeforeAcquired(self) -> None:
"""
When canceling a L{Deferred} from a L{DeferredSemaphore} that does
not yet have the semaphore (i.e., the L{Deferred} has not fired),
the cancel should cause a L{defer.CancelledError} failure.
"""
sem = DeferredSemaphore(1)
sem.acquire()
d = sem.acquire()
d.cancel()
self.assertImmediateFailure(d, defer.CancelledError)
def testQueue(self) -> None:
N, M = 2, 2
queue: DeferredQueue[int] = DeferredQueue(N, M)
gotten: List[int] = []
for i in range(M):
queue.get().addCallback(gotten.append)
self.assertRaises(defer.QueueUnderflow, queue.get)
for i in range(M):
queue.put(i)
self.assertEqual(gotten, list(range(i + 1)))
for i in range(N):
queue.put(N + i)
self.assertEqual(gotten, list(range(M)))
self.assertRaises(defer.QueueOverflow, queue.put, None)
gotten = []
for i in range(N):
queue.get().addCallback(gotten.append)
self.assertEqual(gotten, list(range(N, N + i + 1)))
queue = DeferredQueue()
gotten = []
for i in range(N):
queue.get().addCallback(gotten.append)
for i in range(N):
queue.put(i)
self.assertEqual(gotten, list(range(N)))
queue = DeferredQueue(size=0)
self.assertRaises(defer.QueueOverflow, queue.put, None)
queue = DeferredQueue(backlog=0)
self.assertRaises(defer.QueueUnderflow, queue.get)
def test_cancelQueueAfterSynchronousGet(self) -> None:
"""
When canceling a L{Deferred} from a L{DeferredQueue} that already has
a result, the cancel should have no effect.
"""
def failOnErrback(f: Failure) -> None:
self.fail("Unexpected errback call!")
queue: DeferredQueue[None] = DeferredQueue()
d = queue.get()
d.addErrback(failOnErrback)
queue.put(None)
d.cancel()
def test_cancelQueueAfterGet(self) -> None:
"""
When canceling a L{Deferred} from a L{DeferredQueue} that does not
have a result (i.e., the L{Deferred} has not fired), the cancel
causes a L{defer.CancelledError} failure. If the queue has a result
later on, it doesn't try to fire the deferred.
"""
queue: DeferredQueue[None] = DeferredQueue()
d = queue.get()
d.cancel()
self.assertImmediateFailure(d, defer.CancelledError)
def cb(ignore: object) -> Deferred[None]:
# If the deferred is still linked with the deferred queue, it will
# fail with an AlreadyCalledError
queue.put(None)
return queue.get().addCallback(self.assertIs, None)
d.addCallback(cb)
done: List[None] = []
d.addCallback(done.append)
self.assertEqual(len(done), 1)
class DeferredFilesystemLockTests(unittest.TestCase):
"""
Test the behavior of L{DeferredFilesystemLock}
"""
def setUp(self) -> None:
self.clock = Clock()
self.lock = DeferredFilesystemLock(self.mktemp(), scheduler=self.clock)
def test_waitUntilLockedWithNoLock(self) -> Deferred[None]:
"""
Test that the lock can be acquired when no lock is held
"""
return self.lock.deferUntilLocked(timeout=1)
def test_waitUntilLockedWithTimeoutLocked(self) -> Deferred[None]:
"""
Test that the lock can not be acquired when the lock is held
for longer than the timeout.
"""
self.assertTrue(self.lock.lock())
d = self.lock.deferUntilLocked(timeout=5.5)
self.assertFailure(d, defer.TimeoutError)
self.clock.pump([1] * 10)
return d
def test_waitUntilLockedWithTimeoutUnlocked(self) -> Deferred[None]:
"""
Test that a lock can be acquired while a lock is held
but the lock is unlocked before our timeout.
"""
def onTimeout(f: Failure) -> None:
f.trap(defer.TimeoutError)
self.fail("Should not have timed out")
self.assertTrue(self.lock.lock())
self.clock.callLater(1, self.lock.unlock)
d = self.lock.deferUntilLocked(timeout=10)
d.addErrback(onTimeout)
self.clock.pump([1] * 10)
return d
def test_defaultScheduler(self) -> None:
"""
Test that the default scheduler is set up properly.
"""
lock = DeferredFilesystemLock(self.mktemp())
self.assertEqual(lock._scheduler, reactor)
def test_concurrentUsage(self) -> Deferred[None]:
"""
Test that an appropriate exception is raised when attempting
to use deferUntilLocked concurrently.
"""
self.lock.lock()
self.clock.callLater(1, self.lock.unlock)
d1 = self.lock.deferUntilLocked()
d2 = self.lock.deferUntilLocked()
self.assertFailure(d2, defer.AlreadyTryingToLockError)
self.clock.advance(1)
return d1
def test_multipleUsages(self) -> Deferred[None]:
"""
Test that a DeferredFilesystemLock can be used multiple times
"""
def lockAquired(ign: object) -> Deferred[None]:
self.lock.unlock()
d = self.lock.deferUntilLocked()
return d
self.lock.lock()
self.clock.callLater(1, self.lock.unlock)
d = self.lock.deferUntilLocked()
d.addCallback(lockAquired)
self.clock.advance(1)
return d
def test_cancelDeferUntilLocked(self) -> None:
"""
When cancelling a L{Deferred} returned by
L{DeferredFilesystemLock.deferUntilLocked}, the
L{DeferredFilesystemLock._tryLockCall} is cancelled.
"""
self.lock.lock()
deferred = self.lock.deferUntilLocked()
tryLockCall = self.lock._tryLockCall
assert tryLockCall is not None
deferred.cancel()
self.assertFalse(tryLockCall.active())
self.assertIsNone(self.lock._tryLockCall)
self.failureResultOf(deferred, defer.CancelledError)
def test_cancelDeferUntilLockedWithTimeout(self) -> None:
"""
When cancel a L{Deferred} returned by
L{DeferredFilesystemLock.deferUntilLocked}, if the timeout is
set, the timeout call will be cancelled.
"""
self.lock.lock()
deferred = self.lock.deferUntilLocked(timeout=1)
timeoutCall = self.lock._timeoutCall
assert timeoutCall is not None
deferred.cancel()
self.assertFalse(timeoutCall.active())
self.assertIsNone(self.lock._timeoutCall)
self.failureResultOf(deferred, defer.CancelledError)
def _overrideFunc(v: object, t: float) -> str:
"""
Private function to be used to pass as an alternate onTimeoutCancel value
to timeoutDeferred
"""
return "OVERRIDDEN"
class DeferredAddTimeoutTests(unittest.SynchronousTestCase):
"""
Tests for the function L{Deferred.addTimeout}
"""
def test_timeoutChainable(self) -> None:
"""
L{Deferred.addTimeout} returns its own L{Deferred} so it
can be called in a callback chain.
"""
d: Deferred[None] = Deferred()
d.addTimeout(5, Clock())
d.addCallback(lambda _: "done")
d.callback(None)
self.assertEqual("done", self.successResultOf(d))
def test_successResultBeforeTimeout(self) -> None:
"""
The L{Deferred} callbacks with the result if it succeeds before
the timeout. No cancellation happens after the callback either,
which could also cancel inner deferreds.
"""
clock = Clock()
d: Deferred[str] = Deferred()
d.addTimeout(10, clock)
# addTimeout is added first so that if d is timed out, d would be
# canceled before innerDeferred gets returned from an callback on d
innerDeferred: Deferred[None] = Deferred()
dCallbacked: Optional[str] = None
def onCallback(results: str) -> Deferred[None]:
nonlocal dCallbacked
dCallbacked = results
return innerDeferred
d.addCallback(onCallback)
d.callback("results")
# d is callbacked immediately, before innerDeferred is returned from
# the callback on d
self.assertIsNot(None, dCallbacked)
self.assertEqual(dCallbacked, "results")
# The timeout never happens - if it did, d would have been cancelled,
# which would cancel innerDeferred too.
clock.advance(15)
self.assertNoResult(innerDeferred)
def test_successResultBeforeTimeoutCustom(self) -> None:
"""
The L{Deferred} callbacks with the result if it succeeds before
the timeout, even if a custom C{onTimeoutCancel} function is provided.
No cancellation happens after the callback either, which could also
cancel inner deferreds.
"""
clock = Clock()
d: Deferred[str] = Deferred()
d.addTimeout(10, clock, onTimeoutCancel=_overrideFunc)
# addTimeout is added first so that if d is timed out, d would be
# canceled before innerDeferred gets returned from an callback on d
innerDeferred: Deferred[None] = Deferred()
dCallbacked: Optional[str] = None
def onCallback(results: str) -> Deferred[None]:
nonlocal dCallbacked
dCallbacked = results
return innerDeferred
d.addCallback(onCallback)
d.callback("results")
# d is callbacked immediately, before innerDeferred is returned from
# the callback on d
self.assertIsNot(None, dCallbacked)
self.assertEqual(dCallbacked, "results")
# The timeout never happens - if it did, d would have been cancelled,
# which would cancel innerDeferred too
clock.advance(15)
self.assertNoResult(innerDeferred)
def test_failureBeforeTimeout(self) -> None:
"""
The L{Deferred} errbacks with the failure if it fails before the
timeout. No cancellation happens after the errback either, which
could also cancel inner deferreds.
"""
clock = Clock()
d: Deferred[None] = Deferred()
d.addTimeout(10, clock)
# addTimeout is added first so that if d is timed out, d would be
# canceled before innerDeferred gets returned from an errback on d
innerDeferred: Deferred[None] = Deferred()
dErrbacked: Optional[Failure] = None
error = ValueError("fail")
def onErrback(f: Failure) -> Deferred[None]:
nonlocal dErrbacked
dErrbacked = f
return innerDeferred
d.addErrback(onErrback)
d.errback(error)
# d is errbacked immediately, before innerDeferred is returned from the
# errback on d
assert dErrbacked is not None
self.assertIsInstance(dErrbacked, Failure)
self.assertIs(dErrbacked.value, error)
# The timeout never happens - if it did, d would have been cancelled,
# which would cancel innerDeferred too
clock.advance(15)
self.assertNoResult(innerDeferred)
def test_failureBeforeTimeoutCustom(self) -> None:
"""
The L{Deferred} errbacks with the failure if it fails before the
timeout, even if using a custom C{onTimeoutCancel} function.
No cancellation happens after the errback either, which could also
cancel inner deferreds.
"""
clock = Clock()
d: Deferred[None] = Deferred()
d.addTimeout(10, clock, onTimeoutCancel=_overrideFunc)
# addTimeout is added first so that if d is timed out, d would be
# canceled before innerDeferred gets returned from an errback on d
innerDeferred: Deferred[None] = Deferred()
dErrbacked: Optional[Failure] = None
error = ValueError("fail")
def onErrback(f: Failure) -> Deferred[None]:
nonlocal dErrbacked
dErrbacked = f
return innerDeferred
d.addErrback(onErrback)
d.errback(error)
# d is errbacked immediately, before innerDeferred is returned from the
# errback on d
assert dErrbacked is not None
self.assertIsInstance(dErrbacked, Failure)
self.assertIs(dErrbacked.value, error)
# The timeout never happens - if it did, d would have been cancelled,
# which would cancel innerDeferred too
clock.advance(15)
self.assertNoResult(innerDeferred)
def test_timedOut(self) -> None:
"""
The L{Deferred} by default errbacks with a L{defer.TimeoutError}
if it times out before callbacking or errbacking.
"""
clock = Clock()
d: Deferred[None] = Deferred()
d.addTimeout(10, clock)
self.assertNoResult(d)
clock.advance(15)
self.failureResultOf(d, defer.TimeoutError)
def test_timedOutCustom(self) -> None:
"""
If a custom C{onTimeoutCancel] function is provided, the
L{Deferred} returns the custom function's return value if the
L{Deferred} times out before callbacking or errbacking.
The custom C{onTimeoutCancel} function can return a result instead of
a failure.
"""
clock = Clock()
d: Deferred[None] = Deferred()
d.addTimeout(10, clock, onTimeoutCancel=_overrideFunc)
self.assertNoResult(d)
clock.advance(15)
self.assertEqual("OVERRIDDEN", self.successResultOf(d))
def test_timedOutProvidedCancelSuccess(self) -> None:
"""
If a cancellation function is provided when the L{Deferred} is
initialized, the L{Deferred} returns the cancellation value's
non-failure return value when the L{Deferred} times out.
"""
clock = Clock()
d: Deferred[str] = Deferred(lambda c: c.callback("I was cancelled!"))
d.addTimeout(10, clock)
self.assertNoResult(d)
clock.advance(15)
self.assertEqual(self.successResultOf(d), "I was cancelled!")
def test_timedOutProvidedCancelFailure(self) -> None:
"""
If a cancellation function is provided when the L{Deferred} is
initialized, the L{Deferred} returns the cancellation value's
non-L{CanceledError} failure when the L{Deferred} times out.
"""
clock = Clock()
error = ValueError("what!")
d: Deferred[None] = Deferred(lambda c: c.errback(error))
d.addTimeout(10, clock)
self.assertNoResult(d)
clock.advance(15)
f = self.failureResultOf(d, ValueError)
self.assertIs(f.value, error)
def test_cancelBeforeTimeout(self) -> None:
"""
If the L{Deferred} is manually cancelled before the timeout, it
is not re-cancelled (no L{AlreadyCancelled} error, and also no
canceling of inner deferreds), and the default C{onTimeoutCancel}
function is not called, preserving the original L{CancelledError}.
"""
clock = Clock()
d: Deferred[None] = Deferred()
d.addTimeout(10, clock)
# addTimeout is added first so that if d is timed out, d would be
# canceled before innerDeferred gets returned from an errback on d
innerDeferred: Deferred[None] = Deferred()
dCanceled = None
def onErrback(f: Failure) -> Deferred[None]:
nonlocal dCanceled
dCanceled = f
return innerDeferred
d.addErrback(onErrback)
d.cancel()
# d is cancelled immediately, before innerDeferred is returned from the
# errback on d
assert dCanceled is not None
self.assertIsInstance(dCanceled, Failure)
self.assertIs(dCanceled.type, defer.CancelledError)
# The timeout never happens - if it did, d would have been cancelled
# again, which would cancel innerDeferred too
clock.advance(15)
self.assertNoResult(innerDeferred)
def test_cancelBeforeTimeoutCustom(self) -> None:
"""
If the L{Deferred} is manually cancelled before the timeout, it
is not re-cancelled (no L{AlreadyCancelled} error, and also no
canceling of inner deferreds), and the custom C{onTimeoutCancel}
function is not called, preserving the original L{CancelledError}.
"""
clock = Clock()
d: Deferred[None] = Deferred()
d.addTimeout(10, clock, onTimeoutCancel=_overrideFunc)
# addTimeout is added first so that if d is timed out, d would be
# canceled before innerDeferred gets returned from an errback on d
innerDeferred: Deferred[None] = Deferred()
dCanceled = None
def onErrback(f: Failure) -> Deferred[None]:
nonlocal dCanceled
dCanceled = f
return innerDeferred
d.addErrback(onErrback)
d.cancel()
# d is cancelled immediately, before innerDeferred is returned from the
# errback on d
assert dCanceled is not None
self.assertIsInstance(dCanceled, Failure)
self.assertIs(dCanceled.type, defer.CancelledError)
# The timeout never happens - if it did, d would have been cancelled
# again, which would cancel innerDeferred too
clock.advance(15)
self.assertNoResult(innerDeferred)
def test_providedCancelCalledBeforeTimeoutCustom(self) -> None:
"""
A custom translation function can handle a L{Deferred} with a
custom cancellation function.
"""
clock = Clock()
d: Deferred[None] = Deferred(lambda c: c.errback(ValueError("what!")))
d.addTimeout(10, clock, onTimeoutCancel=_overrideFunc)
self.assertNoResult(d)
clock.advance(15)
self.assertEqual("OVERRIDDEN", self.successResultOf(d))
def test_errbackAddedBeforeTimeout(self) -> None:
"""
An errback added before a timeout is added errbacks with a
L{defer.CancelledError} when the timeout fires. If the
errback returns the L{defer.CancelledError}, it is translated
to a L{defer.TimeoutError} by the timeout implementation.
"""
clock = Clock()
d: Deferred[None] = Deferred()
dErrbacked = None
def errback(f: Failure) -> Failure:
nonlocal dErrbacked
dErrbacked = f
return f
d.addErrback(errback)
d.addTimeout(10, clock)
clock.advance(15)
assert dErrbacked is not None
self.assertIsInstance(dErrbacked, Failure)
self.assertIsInstance(dErrbacked.value, defer.CancelledError)
self.failureResultOf(d, defer.TimeoutError)
def test_errbackAddedBeforeTimeoutSuppressesCancellation(self) -> None:
"""
An errback added before a timeout is added errbacks with a
L{defer.CancelledError} when the timeout fires. If the
errback suppresses the L{defer.CancelledError}, the deferred
successfully completes.
"""
clock = Clock()
d: Deferred[None] = Deferred()
dErrbacked = None
def errback(f: Failure) -> None:
nonlocal dErrbacked
dErrbacked = f
f.trap(defer.CancelledError)
d.addErrback(errback)
d.addTimeout(10, clock)
clock.advance(15)
assert dErrbacked is not None
self.assertIsInstance(dErrbacked, Failure)
self.assertIsInstance(dErrbacked.value, defer.CancelledError)
self.successResultOf(d)
def test_errbackAddedBeforeTimeoutCustom(self) -> None:
"""
An errback added before a timeout is added with a custom
timeout function errbacks with a L{defer.CancelledError} when
the timeout fires. The timeout function runs if the errback
returns the L{defer.CancelledError}.
"""
clock = Clock()
d: Deferred[None] = Deferred()
dErrbacked = None
def errback(f: Failure) -> Failure:
nonlocal dErrbacked
dErrbacked = f
return f
d.addErrback(errback)
d.addTimeout(10, clock, _overrideFunc)
clock.advance(15)
assert dErrbacked is not None
self.assertIsInstance(dErrbacked, Failure)
self.assertIsInstance(dErrbacked.value, defer.CancelledError)
self.assertEqual("OVERRIDDEN", self.successResultOf(d))
def test_errbackAddedBeforeTimeoutSuppressesCancellationCustom(self) -> None:
"""
An errback added before a timeout is added with a custom
timeout function errbacks with a L{defer.CancelledError} when
the timeout fires. The timeout function runs if the errback
suppresses the L{defer.CancelledError}.
"""
clock = Clock()
d: Deferred[None] = Deferred()
dErrbacked = None
def errback(f: Failure) -> None:
nonlocal dErrbacked
dErrbacked = f
d.addErrback(errback)
d.addTimeout(10, clock, _overrideFunc)
clock.advance(15)
assert dErrbacked is not None
self.assertIsInstance(dErrbacked, Failure)
self.assertIsInstance(dErrbacked.value, defer.CancelledError)
self.assertEqual("OVERRIDDEN", self.successResultOf(d))
def test_callbackAddedToCancelerBeforeTimeout(self) -> None:
"""
Given a deferred with a cancellation function that resumes the
callback chain, a callback that is added to the deferred
before a timeout is added to runs when the timeout fires. The
deferred completes successfully, without a
L{defer.TimeoutError}.
"""
clock = Clock()
success = "success"
d: Deferred[str] = Deferred(lambda d: d.callback(success))
dCallbacked = None
def callback(value: str) -> str:
nonlocal dCallbacked
dCallbacked = value
return value
d.addCallback(callback)
d.addTimeout(10, clock)
clock.advance(15)
self.assertEqual(dCallbacked, success)
self.assertIs(success, self.successResultOf(d))
def test_callbackAddedToCancelerBeforeTimeoutCustom(self) -> None:
"""
Given a deferred with a cancellation function that resumes the
callback chain, a callback that is added to the deferred
before a timeout is added to runs when the timeout fires. The
deferred completes successfully, without a
L{defer.TimeoutError}. The timeout's custom timeout function
also runs.
"""
clock = Clock()
success = "success"
d: Deferred[str] = Deferred(lambda d: d.callback(success))
dCallbacked = None
def callback(value: str) -> str:
nonlocal dCallbacked
dCallbacked = value
return value
d.addCallback(callback)
d.addTimeout(10, clock, onTimeoutCancel=_overrideFunc)
clock.advance(15)
self.assertEqual(dCallbacked, success)
self.assertEqual("OVERRIDDEN", self.successResultOf(d))
class EnsureDeferredTests(unittest.TestCase):
"""
Tests for L{ensureDeferred}.
"""
def test_passesThroughDeferreds(self) -> None:
"""
L{ensureDeferred} will pass through a Deferred unchanged.
"""
d1: Deferred[None] = Deferred()
d2 = ensureDeferred(d1)
self.assertIs(d1, d2)
def test_willNotAllowNonDeferredOrCoroutine(self) -> None:
"""
Passing L{ensureDeferred} a non-coroutine and a non-Deferred will
raise a L{ValueError}.
"""
with self.assertRaises(defer.NotACoroutineError):
ensureDeferred("something") # type: ignore[arg-type]
def test_ensureDeferredCoroutine(self) -> None:
"""
L{ensureDeferred} will turn a coroutine into a L{Deferred}.
"""
async def run() -> str:
d = defer.succeed("foo")
res = await d
return res
# It's a coroutine...
r = run()
self.assertIsInstance(r, types.CoroutineType)
# Now it's a Deferred.
d = ensureDeferred(r)
assert_type(d, Deferred[str])
self.assertIsInstance(d, Deferred)
# The Deferred has the result we want.
res = self.successResultOf(d)
self.assertEqual(res, "foo")
def test_ensureDeferredGenerator(self) -> None:
"""
L{ensureDeferred} will turn a yield-from coroutine into a L{Deferred}.
"""
def run() -> Generator[Deferred[str], None, str]:
d = defer.succeed("foo")
res = cast(str, (yield from d))
return res
# It's a generator...
r = run()
self.assertIsInstance(r, types.GeneratorType)
# Now it's a Deferred.
d = ensureDeferred(r)
assert_type(d, Deferred[str])
self.assertIsInstance(d, Deferred)
# The Deferred has the result we want.
res = self.successResultOf(d)
self.assertEqual(res, "foo")
class TimeoutErrorTests(unittest.TestCase, ImmediateFailureMixin):
"""
L{twisted.internet.defer} timeout code.
"""
def test_deprecatedTimeout(self) -> None:
"""
L{twisted.internet.defer.timeout} is deprecated.
"""
deferred: Deferred[object] = Deferred()
defer.timeout(deferred)
self.assertFailure(deferred, defer.TimeoutError)
warningsShown = self.flushWarnings([self.test_deprecatedTimeout])
self.assertEqual(len(warningsShown), 1)
self.assertIs(warningsShown[0]["category"], DeprecationWarning)
self.assertEqual(
warningsShown[0]["message"],
"twisted.internet.defer.timeout was deprecated in Twisted 17.1.0;"
" please use twisted.internet.defer.Deferred.addTimeout instead",
)
def callAllSoonCalls(loop: AbstractEventLoop) -> None:
"""
Tickle an asyncio event loop to call all of the things scheduled with
call_soon, inasmuch as this can be done via the public API.
@param loop: The asyncio event loop to flush the previously-called
C{call_soon} entries from.
"""
loop.call_soon(loop.stop)
loop.run_forever()
class DeferredFutureAdapterTests(unittest.TestCase):
def newLoop(self) -> AbstractEventLoop:
"""
Create a new event loop that will be closed at the end of the test.
"""
result = _new_event_loop()
self.addCleanup(result.close)
return result
def test_asFuture(self) -> None:
"""
L{Deferred.asFuture} returns a L{asyncio.Future} which fires when
the given L{Deferred} does.
"""
d: Deferred[int] = Deferred()
loop = self.newLoop()
aFuture = d.asFuture(loop)
self.assertEqual(aFuture.done(), False)
d.callback(13)
callAllSoonCalls(loop)
self.assertEqual(self.successResultOf(d), None)
self.assertEqual(aFuture.result(), 13)
def test_asFutureCancelFuture(self) -> None:
"""
L{Deferred.asFuture} returns a L{asyncio.Future} which, when
cancelled, will cancel the original L{Deferred}.
"""
called = False
def canceler(dprime: Deferred[object]) -> None:
nonlocal called
called = True
d: Deferred[None] = Deferred(canceler)
loop = self.newLoop()
aFuture = d.asFuture(loop)
aFuture.cancel()
callAllSoonCalls(loop)
self.assertTrue(called)
self.assertEqual(self.successResultOf(d), None)
self.assertRaises(CancelledError, aFuture.result)
def test_asFutureSuccessCancel(self) -> None:
"""
While Futures don't support succeeding in response to cancellation,
Deferreds do; if a Deferred is coerced into a success by a Future
cancellation, that should just be ignored.
"""
def canceler(dprime: Deferred[object]) -> None:
dprime.callback(9)
d: Deferred[None] = Deferred(canceler)
loop = self.newLoop()
aFuture = d.asFuture(loop)
aFuture.cancel()
callAllSoonCalls(loop)
self.assertEqual(self.successResultOf(d), None)
self.assertRaises(CancelledError, aFuture.result)
def test_asFutureFailure(self) -> None:
"""
L{Deferred.asFuture} makes a L{asyncio.Future} fire with an
exception when the given L{Deferred} does.
"""
d: Deferred[None] = Deferred()
theFailure = Failure(ZeroDivisionError())
loop = self.newLoop()
future = d.asFuture(loop)
callAllSoonCalls(loop)
d.errback(theFailure)
callAllSoonCalls(loop)
self.assertRaises(ZeroDivisionError, future.result)
def test_fromFuture(self) -> None:
"""
L{Deferred.fromFuture} returns a L{Deferred} that fires
when the given L{asyncio.Future} does.
"""
loop = self.newLoop()
aFuture: Future[int] = Future(loop=loop)
d = Deferred.fromFuture(aFuture)
self.assertNoResult(d)
aFuture.set_result(7)
callAllSoonCalls(loop)
self.assertEqual(self.successResultOf(d), 7)
def test_fromFutureFutureCancelled(self) -> None:
"""
L{Deferred.fromFuture} makes a L{Deferred} fire with
an L{asyncio.CancelledError} when the given
L{asyncio.Future} is cancelled.
"""
loop = self.newLoop()
cancelled: Future[None] = Future(loop=loop)
d = Deferred.fromFuture(cancelled)
cancelled.cancel()
callAllSoonCalls(loop)
self.assertRaises(CancelledError, cancelled.result)
self.failureResultOf(d).trap(CancelledError)
def test_fromFutureDeferredCancelled(self) -> None:
"""
L{Deferred.fromFuture} makes a L{Deferred} which, when
cancelled, cancels the L{asyncio.Future} it was created from.
"""
loop = self.newLoop()
cancelled: Future[None] = Future(loop=loop)
d = Deferred.fromFuture(cancelled)
d.cancel()
callAllSoonCalls(loop)
self.assertEqual(cancelled.cancelled(), True)
self.assertRaises(CancelledError, cancelled.result)
self.failureResultOf(d).trap(CancelledError)
class CoroutineContextVarsTests(unittest.TestCase):
def test_withInlineCallbacks(self) -> None:
"""
When an inlineCallbacks function is called, the context is taken from
when it was first called. When it resumes, the same context is applied.
"""
clock = Clock()
var: contextvars.ContextVar[int] = contextvars.ContextVar("testvar")
var.set(1)
# This Deferred will set its own context to 3 when it is called
mutatingDeferred: Deferred[bool] = Deferred()
mutatingDeferred.addCallback(lambda _: var.set(3))
mutatingDeferredThatFails: Deferred[int] = Deferred()
mutatingDeferredThatFails.addCallback(lambda _: var.set(4))
mutatingDeferredThatFails.addCallback(lambda _: 1 / 0)
@defer.inlineCallbacks
def yieldingDeferred() -> Generator[Deferred[Any], Any, None]:
d: Deferred[int] = Deferred()
clock.callLater(1, d.callback, True)
yield d
var.set(3)
assert_type(yieldingDeferred, Callable[[], Deferred[None]])
# context is 1 when the function is defined
@defer.inlineCallbacks
def testFunction() -> Generator[Deferred[Any], Any, None]:
# Expected to be 2
self.assertEqual(var.get(), 2)
# Does not mutate the context
yield defer.succeed(1)
# Expected to be 2
self.assertEqual(var.get(), 2)
# mutatingDeferred mutates it to 3, but only in its Deferred chain
clock.callLater(1, mutatingDeferred.callback, True)
yield mutatingDeferred
# When it resumes, it should still be 2
self.assertEqual(var.get(), 2)
# mutatingDeferredThatFails mutates it to 3, but only in its
# Deferred chain
clock.callLater(1, mutatingDeferredThatFails.callback, True)
try:
yield mutatingDeferredThatFails
except Exception:
self.assertEqual(var.get(), 2)
else:
raise Exception("???? should have failed")
# IMPLEMENTATION DETAIL: Because inlineCallbacks must be at every
# level, an inlineCallbacks function yielding another
# inlineCallbacks function will NOT mutate the outer one's context,
# as it is copied when the inner one is ran and mutated there.
yield yieldingDeferred()
self.assertEqual(var.get(), 2)
defer.returnValue(True)
assert_type(testFunction, Callable[[], Deferred[None]])
# The inlineCallbacks context is 2 when it's called
var.set(2)
d = testFunction()
# Advance the clock so mutatingDeferred triggers
clock.advance(1)
# Advance the clock so that mutatingDeferredThatFails triggers
clock.advance(1)
# Advance the clock so that yieldingDeferred triggers
clock.advance(1)
self.assertEqual(self.successResultOf(d), True)
def test_resetWithInlineCallbacks(self) -> None:
"""
When an inlineCallbacks function resumes, we should be able to reset() a
contextvar that was set when it was first called.
"""
clock = Clock()
var: contextvars.ContextVar[int] = contextvars.ContextVar("testvar")
@defer.inlineCallbacks
def yieldingDeferred() -> Generator[Deferred[Any], Any, None]:
# first try setting the var
token = var.set(3)
# after a sleep, try resetting it
d: Deferred[int] = Deferred()
clock.callLater(1, d.callback, True)
yield d
self.assertEqual(var.get(), 3)
var.reset(token)
# it should have gone back to what we started with (2)
self.assertEqual(var.get(), 2)
# we start off with the var set to 2
var.set(2)
d = yieldingDeferred()
# Advance the clock so that yieldingDeferred triggers
clock.advance(1)
self.successResultOf(d)
@ensuringDeferred
async def test_asyncWithLock(self) -> None:
"""
L{DeferredLock} can be used as an asynchronous context manager.
"""
lock = DeferredLock()
d = None # This makes mypy check that async with doesn't suppress exceptions.
async with lock:
self.assertTrue(lock.locked)
d = lock.acquire()
d.addCallback(lambda _: lock.release())
self.assertTrue(lock.locked)
self.assertFalse(d.called)
self.assertTrue(d.called)
await d
self.assertFalse(lock.locked)
@ensuringDeferred
async def test_asyncWithSemaphore(self) -> None:
"""
L{DeferredSemaphore} can be used as an asynchronous context
manager.
"""
sem = DeferredSemaphore(3)
async with sem:
self.assertEqual(sem.tokens, 2)
async with sem:
self.assertEqual(sem.tokens, 1)
d1 = sem.acquire()
d2 = sem.acquire()
self.assertEqual(sem.tokens, 0)
self.assertTrue(d1.called)
self.assertFalse(d2.called)
self.assertEqual(sem.tokens, 0)
self.assertTrue(d2.called)
d1.addCallback(lambda _: sem.release())
d2.addCallback(lambda _: sem.release())
await d1
await d2
self.assertEqual(sem.tokens, 2)
self.assertEqual(sem.tokens, 3)
@ensuringDeferred
async def test_asyncWithLockException(self) -> None:
"""
C{DeferredLock} correctly propagates exceptions when
used as an asynchronous context manager.
"""
lock = DeferredLock()
with self.assertRaisesRegex(Exception, "some specific exception"):
async with lock:
self.assertTrue(lock.locked)
raise Exception("some specific exception")
self.assertFalse(lock.locked)
def test_contextvarsWithAsyncAwait(self) -> None:
"""
When a coroutine is called, the context is taken from when it was first
called. When it resumes, the same context is applied.
"""
clock = Clock()
var: contextvars.ContextVar[int] = contextvars.ContextVar("testvar")
var.set(1)
# This Deferred will set its own context to 3 when it is called
mutatingDeferred: Deferred[bool] = Deferred()
mutatingDeferred.addCallback(lambda _: var.set(3))
mutatingDeferredThatFails: Deferred[bool] = Deferred()
mutatingDeferredThatFails.addCallback(lambda _: var.set(4))
mutatingDeferredThatFails.addCallback(lambda _: 1 / 0)
async def asyncFuncAwaitingDeferred() -> None:
d: Deferred[bool] = Deferred()
clock.callLater(1, d.callback, True)
await d
var.set(3)
# context is 1 when the function is defined
async def testFunction() -> bool:
# Expected to be 2
self.assertEqual(var.get(), 2)
# Does not mutate the context
await defer.succeed(1)
# Expected to be 2
self.assertEqual(var.get(), 2)
# mutatingDeferred mutates it to 3, but only in its Deferred chain
clock.callLater(0, mutatingDeferred.callback, True)
await mutatingDeferred
# When it resumes, it should still be 2
self.assertEqual(var.get(), 2)
# mutatingDeferredThatFails mutates it to 3, but only in its
# Deferred chain
clock.callLater(1, mutatingDeferredThatFails.callback, True)
try:
await mutatingDeferredThatFails
except Exception:
self.assertEqual(var.get(), 2)
else:
raise Exception("???? should have failed")
# If we await another async def-defined function, it will be able
# to mutate the outer function's context, it is *not* frozen and
# restored inside the function call.
await asyncFuncAwaitingDeferred()
self.assertEqual(var.get(), 3)
return True
# The inlineCallbacks context is 2 when it's called
var.set(2)
d = ensureDeferred(testFunction())
# Advance the clock so mutatingDeferred triggers
clock.advance(1)
# Advance the clock so that mutatingDeferredThatFails triggers
clock.advance(1)
# Advance the clock so that asyncFuncAwaitingDeferred triggers
clock.advance(1)
self.assertEqual(self.successResultOf(d), True)
class InlineCallbackTests(unittest.SynchronousTestCase):
def test_inlineCallbacksTracebacks(self) -> None:
"""
L{defer.inlineCallbacks} that re-raise tracebacks into their deferred
should not lose their tracebacks.
"""
f = getDivisionFailure()
d: Deferred[None] = Deferred()
try:
f.raiseException()
except BaseException:
d.errback()
def ic(d: object) -> Generator[Any, Any, None]:
yield d
defer.inlineCallbacks(ic)
newFailure = self.failureResultOf(d)
tb = traceback.extract_tb(newFailure.getTracebackObject())
self.assertEqual(len(tb), 3)
self.assertIn("test_defer", tb[2][0])
self.assertEqual("getDivisionFailure", tb[2][2])
self.assertEqual("1 / 0", tb[2][3])
self.assertIn("test_defer", tb[0][0])
self.assertEqual("test_inlineCallbacksTracebacks", tb[0][2])
self.assertEqual("f.raiseException()", tb[0][3])
def test_fromCoroutineRequiresCoroutine(self) -> None:
"""
L{Deferred.fromCoroutine} requires a coroutine object or a generator,
and will reject things that are not that.
"""
thingsThatAreNotCoroutines = [
# Lambda
lambda x: x,
# Int
1,
# Boolean
True,
# Function
self.test_fromCoroutineRequiresCoroutine,
# None
None,
# Module
defer,
]
for thing in thingsThatAreNotCoroutines:
self.assertRaises(defer.NotACoroutineError, Deferred.fromCoroutine, thing)
def test_inlineCallbacksCancelCaptured(self) -> None:
"""
Cancelling an L{defer.inlineCallbacks} correctly handles the function
catching the L{defer.CancelledError}.
The desired behavior is:
1. If the function is waiting on an inner deferred, that inner
deferred is cancelled, and a L{defer.CancelledError} is raised
within the function.
2. If the function catches that exception, execution continues, and
the deferred returned by the function is not resolved.
3. Cancelling the deferred again cancels any deferred the function
is waiting on, and the exception is raised.
"""
canceller1Calls: List[Deferred[object]] = []
canceller2Calls: List[Deferred[object]] = []
d1: Deferred[object] = Deferred(canceller1Calls.append)
d2: Deferred[object] = Deferred(canceller2Calls.append)
@defer.inlineCallbacks
def testFunc() -> Generator[Deferred[object], object, None]:
try:
yield d1
except Exception:
pass
yield d2
# Call the function, and ensure that none of the deferreds have
# completed or been cancelled yet.
funcD = testFunc()
self.assertNoResult(d1)
self.assertNoResult(d2)
self.assertNoResult(funcD)
self.assertEqual(canceller1Calls, [])
self.assertEqual(canceller1Calls, [])
# Cancel the deferred returned by the function, and check that the first
# inner deferred has been cancelled, but the returned deferred has not
# completed (as the function catches the raised exception).
funcD.cancel()
self.assertEqual(canceller1Calls, [d1])
self.assertEqual(canceller2Calls, [])
self.assertNoResult(funcD)
# Cancel the returned deferred again, this time the returned deferred
# should have a failure result, as the function did not catch the cancel
# exception raised by `d2`.
funcD.cancel()
failure = self.failureResultOf(funcD)
self.assertEqual(failure.type, defer.CancelledError)
self.assertEqual(canceller2Calls, [d2])
@pyunit.skipIf(_PYPY, "GC works differently on PyPy.")
def test_inlineCallbacksNoCircularReference(self) -> None:
"""
When using L{defer.inlineCallbacks}, after the function exits, it will
not keep references to the function itself or the arguments.
This ensures that the machinery gets deallocated immediately rather than
waiting for a GC, on CPython.
The GC on PyPy works differently (del doesn't immediately deallocate the
object), so we skip the test.
"""
# Create an object and weak reference to track if its gotten freed.
obj: Set[Any] = set()
objWeakRef = weakref.ref(obj)
@defer.inlineCallbacks
def func(a: Any) -> Any:
yield a
return a
# Run the function
funcD = func(obj)
self.assertEqual(obj, self.successResultOf(funcD))
funcDWeakRef = weakref.ref(funcD)
# Delete the local references to obj and funcD.
del obj
del funcD
# The object has been freed if the weak reference returns None.
self.assertIsNone(objWeakRef())
self.assertIsNone(funcDWeakRef())
@pyunit.skipIf(_PYPY, "GC works differently on PyPy.")
def test_coroutineNoCircularReference(self) -> None:
"""
Tests that there is no circular dependency when using
L{Deferred.fromCoroutine}, so that the machinery gets cleaned up
immediately rather than waiting for a GC.
"""
# Create an object and weak reference to track if its gotten freed.
obj: Set[Any] = set()
objWeakRef = weakref.ref(obj)
async def func(a: Any) -> Any:
return a
# Run the function
funcD = Deferred.fromCoroutine(func(obj))
self.assertEqual(obj, self.successResultOf(funcD))
funcDWeakRef = weakref.ref(funcD)
# Delete the local references to obj and funcD.
del obj
del funcD
# The object has been freed if the weak reference returns None.
self.assertIsNone(objWeakRef())
self.assertIsNone(funcDWeakRef())
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