import trio
import tractor


async def assert_err() -> None:
    '''
    Raise an assertion error in the current actor.

    '''
    assert 0


async def main() -> None:
    '''
    Propagate a failing one-shot task from a subactor.

    '''
    an: tractor.ActorNursery
    async with tractor.open_nursery() as an:
        real_actors: list[tractor.Portal] = []
        i: int
        for i in range(3):
            real_actors.append(
                await an.start_actor(
                    f'actor_{i}',
                    enable_modules=[__name__],
                )
            )

        # run one one-shot task actor that will fail immediately;
        # its error raises right here in the caller's task..
        await tractor.to_actor.run(assert_err, an=an)

    # ..as a ``RemoteActorError`` containing an ``AssertionError``
    # and all the other actors have been cancelled


if __name__ == '__main__':
    try:
        # also raises
        trio.run(main)
    except tractor.RemoteActorError:
        print('Look Maa that actor failed hard, hehhh!')