def test_unlockOther(self):
        """
        L{FilesystemLock.unlock} raises L{ValueError} if called for a lock
        which is held by a different process.
        """
        lockf = self.mktemp()
        lockfile.symlink(str(os.getpid() + 1), lockf)
        lock = lockfile.FilesystemLock(lockf)
        self.assertRaises(ValueError, lock.unlock)

        L{FilesystemLock.unlock} raises L{ValueError} if called for a lock
        which is held by a different process.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_lockfile.py