Current File : //lib/python3/dist-packages/twisted/internet/test/test_sigchld.py
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Tests for L{twisted.internet._sigchld}, an alternate, superior SIGCHLD
monitoring API.
"""
from __future__ import annotations
import errno
import os
import signal
from twisted.python.runtime import platformType
from twisted.trial.unittest import SynchronousTestCase
if platformType == "posix":
from twisted.internet._signals import installHandler, isDefaultHandler
from twisted.internet.fdesc import setNonBlocking
else:
skip = "These tests can only run on POSIX platforms."
class SetWakeupSIGCHLDTests(SynchronousTestCase):
"""
Tests for the L{signal.set_wakeup_fd} implementation of the
L{installHandler} and L{isDefaultHandler} APIs.
"""
def pipe(self) -> tuple[int, int]:
"""
Create a non-blocking pipe which will be closed after the currently
running test.
"""
read, write = os.pipe()
self.addCleanup(os.close, read)
self.addCleanup(os.close, write)
setNonBlocking(read)
setNonBlocking(write)
return read, write
def setUp(self) -> None:
"""
Save the current SIGCHLD handler as reported by L{signal.signal} and
the current file descriptor registered with L{installHandler}.
"""
self.signalModuleHandler = signal.getsignal(signal.SIGCHLD)
self.oldFD = installHandler(-1)
def tearDown(self) -> None:
"""
Restore whatever signal handler was present when setUp ran.
"""
# If tests set up any kind of handlers, clear them out.
installHandler(self.oldFD)
signal.signal(signal.SIGCHLD, self.signalModuleHandler)
def test_isDefaultHandler(self) -> None:
"""
L{isDefaultHandler} returns true if the SIGCHLD handler is SIG_DFL,
false otherwise.
"""
self.assertTrue(isDefaultHandler())
signal.signal(signal.SIGCHLD, signal.SIG_IGN)
self.assertFalse(isDefaultHandler())
signal.signal(signal.SIGCHLD, signal.SIG_DFL)
self.assertTrue(isDefaultHandler())
signal.signal(signal.SIGCHLD, lambda *args: None)
self.assertFalse(isDefaultHandler())
def test_returnOldFD(self) -> None:
"""
L{installHandler} returns the previously registered file descriptor.
"""
read, write = self.pipe()
oldFD = installHandler(write)
self.assertEqual(installHandler(oldFD), write)
def test_uninstallHandler(self) -> None:
"""
C{installHandler(-1)} removes the SIGCHLD handler completely.
"""
read, write = self.pipe()
self.assertTrue(isDefaultHandler())
installHandler(write)
self.assertFalse(isDefaultHandler())
installHandler(-1)
self.assertTrue(isDefaultHandler())
def test_installHandler(self) -> None:
"""
The file descriptor passed to L{installHandler} has a byte written to
it when SIGCHLD is delivered to the process.
"""
read, write = self.pipe()
installHandler(write)
exc = self.assertRaises(OSError, os.read, read, 1)
self.assertEqual(exc.errno, errno.EAGAIN)
os.kill(os.getpid(), signal.SIGCHLD)
self.assertEqual(len(os.read(read, 5)), 1)
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