"""Test client that connects and sends infinite data."""

import sys

from tulip import *

def dprint(*args):
        print('source:', *args, file=sys.stderr)

class Client(Protocol):

    data = b'x'*16*1024

    def connection_made(self, tr):
        dprint('connecting to', tr.get_extra_info('addr'))
        self.tr = tr
        self.lost = False
        self.loop = get_event_loop()
        self.waiter = Future()
        self.write_some_data()

    def write_some_data(self):
        dprint('writing', len(self.data), 'bytes')
        self.tr.write(self.data)
        if not self.lost:
            self.loop.call_soon(self.write_some_data)

    def connection_lost(self, exc):
        dprint('lost connection', repr(exc))
        self.lost = True
        self.waiter.set_result(None)

@coroutine
def start(loop):
    tr, pr = yield from loop.create_connection(Client, 'localhost', 1111)
    dprint('tr =', tr)
    dprint('pr =', pr)
    res = yield from pr.waiter
    return res

def main():
    loop = get_event_loop()
    loop.run_until_complete(start(loop))

if __name__ == '__main__':
    main()

"""Test client that connects and sends infinite data."""

import sys

from tulip import *

def dprint(*args):
        print('source:', *args, file=sys.stderr)

class Client(Protocol):

    data = b'x'*16*1024

    def connection_made(self, tr):
        dprint('connecting to', tr.get_extra_info('addr'))
        self.tr = tr
        self.lost = False
        self.loop = get_event_loop()
        self.waiter = Future()
        self.write_some_data()

    def write_some_data(self):
        if self.lost:
            dprint('lost already')
            return
        dprint('writing', len(self.data), 'bytes')
        self.tr.write(self.data)
        self.loop.call_soon(self.write_some_data)

    def connection_lost(self, exc):
        dprint('lost connection', repr(exc))
        self.lost = True
        self.waiter.set_result(None)

@coroutine
def start(loop):
    tr, pr = yield from loop.create_connection(Client, 'localhost', 1111)
    dprint('tr =', tr)
    dprint('pr =', pr)
    res = yield from pr.waiter
    return res

def main():
    loop = get_event_loop()
    loop.run_until_complete(start(loop))

if __name__ == '__main__':
    main()

Fix logic around lost connection.