import asyncio


async def ping(reader: asyncio.StreamReader, writer: asyncio.StreamWriter):
    try:
        print('client connected')
        while not reader.at_eof():
            data = await reader.readline()
            print('received data')
            writer.write(b'pong ' + data)
            await writer.drain()
            print('send pong')
    except asyncio.CancelledError:
        print('Connection cancelled')  # never called
    finally:
        print('Connection closed!')  # never called


class Factory:
    def __init__(self, loop, callback):
        self.loop = loop
        self.callback = callback

    def __call__(self):
        reader = asyncio.StreamReader(loop=self.loop)
        return asyncio.StreamReaderProtocol(reader, self.callback, loop=loop)

HOST = 'localhost'
PORT = 9999

async def client(loop: asyncio.AbstractEventLoop):
    reader, writer = await asyncio.open_connection(HOST, PORT, loop=loop)
    print('connected to server')
    writer.write(b'hi!\n')
    await writer.drain()
    print('hi server!')
    data = await reader.readline()
    print('server answer ' + str(data, encoding='utf-8'))
    # writer.close()
    # print('closed')


async def close_server(server):
    return await server.wait_close()


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    server = loop.run_until_complete(
        loop.create_server(Factory(loop, ping), host=HOST, port=PORT)
    )
    loop.run_until_complete(client(loop))
    server.close()
    loop.run_until_complete(server.wait_closed())
    print(asyncio.Task.all_tasks())
    print(loop._ready)