Trio echo client and server example

trio_test.py

import trio

async def test_client(value):
    stream = await trio.open_tcp_stream('127.0.0.1', 8000)
    async with stream:
        await stream.send_all(value)
        return await stream.receive_some(4096)

async def start_server(**kwargs):
    async def _echo_handler(stream):
        while 1:
            data = await stream.receive_some(4096)
            if not data:
                break
            await stream.send_all(data)
    await trio.serve_tcp(_echo_handler, 8000, host='127.0.0.1', **kwargs)


async def main():
    async with trio.open_nursery() as nursery:
        await nursery.start(start_server)
        assert await test_client(b'test') == b'test'
        nursery.cancel_scope.cancel()
    
if __name__ == '__main__':
    trio.run(main)