def METHOD_NAME(tmpdir):
    fake_img = str(tmpdir / 'hello_stopped')
    with open(fake_img, 'w+') as f:
        f.write('hello')
    event = threading.Event()
    event.set()
    assert md5sum(fake_img, stopped_event=event) is None
    assert not os.path.exists(str(tmpdir / 'hello_stopped.md5sum'))