micropython/tests/extmod/asyncio_cancel_wait_on_finished.py

# Test cancelling a task that is waiting on a task that just finishes.

try:
    import asyncio
except ImportError:
    print("SKIP")
    raise SystemExit


async def sleep_task():
    print("sleep_task sleep")
    await asyncio.sleep(0)
    print("sleep_task wake")


async def wait_task(t):
    print("wait_task wait")
    await t
    print("wait_task wake")


async def main():
    waiting_task = asyncio.create_task(wait_task(asyncio.create_task(sleep_task())))

    print("main sleep")
    await asyncio.sleep(0)
    print("main sleep")
    await asyncio.sleep(0)

    waiting_task.cancel()
    print("main wait")
    try:
        await waiting_task
    except asyncio.CancelledError as er:
        print(repr(er))


asyncio.run(main())