line_request.py

from twisted.protocols.basic import LineOnlyReceiver
from twisted.internet.defer import Deferred
from twisted.internet.endpoints import TCP4ClientEndpoint, connectProtocol


class MyLineReceiver(LineOnlyReceiver):
    def __init__(self, to_send):
        self._to_send = to_send
        self.deferred = Deferred()
        self._received = []

    def connectionMade(self):
        self.sendLine(self._to_send)

    def lineReceived(self, line):
        self._received.append(line)
        if 'END' in line:
            self.transport.loseConnection()

    def connectionLost(self, reason):
        # TODO: check reason and maybe errback
        self.deferred.callback(self._received)


def do_request(addr, request):
    ep = TCP4ClientEndpoint(reactor, addr, 8080)
    return (connectProtocol(ep, MyLineReceiver(request))
        .addCallback(lambda proto: proto.deferred)
    )


@inlineCallbacks
def foo():
    response = yield do_request('127.0.0.1', 'here is a line')
    assert response == ['OK response here', 'another line', 'END']