import asyncio
import tty
import pty
import io


async def get_pipes(limit=None, loop=None):
    if not loop:
        loop = asyncio.get_event_loop()
    if not limit:
        limit = asyncio.streams._DEFAULT_LIMIT

    master, slave = pty.openpty()
    tty.setraw(master)
    tty.setraw(slave)

    writer_pipe = io.open(master, 'wb', 0)
    reader_pipe = io.open(slave, 'rb', 0)

    reader = asyncio.StreamReader(loop=loop, limit=limit)
    reader_protocol = asyncio.StreamReaderProtocol(reader, loop=loop)
    reader_transport, _ = await loop.connect_read_pipe(lambda: reader_protocol, reader_pipe)

    writer_transport, writer_protocol = await loop.connect_write_pipe(asyncio.streams.FlowControlMixin, writer_pipe)
    writer = asyncio.StreamWriter(writer_transport, writer_protocol, reader, loop)
    return reader, writer


async def test(msg):
    reader, writer = await get_pipes()
    bmsg = msg.encode("utf-8")
    writer.write(bmsg)
    await writer.drain()
    result = await reader.read()
    assert result == bmsg
    print(result)


def run_test():
    loop = asyncio.get_event_loop()
    loop.run_until_complete(test("Hello World!"))


if __name__ == "__main__":
    run_test()