def test_rmlinkError(self):
        """
        An exception raised by L{rmlink} other than C{ENOENT} is passed up
        to the caller of L{FilesystemLock.lock}.
        """
        def fakeRmlink(name):
            raise OSError(errno.ENOSYS, None)
        self.patch(lockfile, 'rmlink', fakeRmlink)

        def fakeKill(pid, signal):
            if signal != 0:
                raise OSError(errno.EPERM, None)
            if pid == 43125:
                raise OSError(errno.ESRCH, None)
        self.patch(lockfile, 'kill', fakeKill)

        lockf = self.mktemp()

        # Make it appear locked so it has to use readlink
        lockfile.symlink(str(43125), lockf)

        lock = lockfile.FilesystemLock(lockf)
        exc = self.assertRaises(OSError, lock.lock)
        self.assertEqual(exc.errno, errno.ENOSYS)
        self.assertFalse(lock.locked)

        An exception raised by L{rmlink} other than C{ENOENT} is passed up
        to the caller of L{FilesystemLock.lock}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_lockfile.py