foobar.py

from contextlib import closing
from threading import Thread
import zmq
import time
from pathlib import Path


class AbstractWidget:
    def __init__(self):
        self.config = Path("config.json").read_text()


class FooWidget(AbstractWidget):
    def __init__(self):
        super().__init__()
        self.ctx = zmq.Context.instance()
        self.consumer: zmq.Socket = self.ctx.socket(zmq.PULL)
        self.should_exit = False

    def run(self):
        while self.should_exit is False:
            time.sleep(1)

        self.consumer.close()

    def close(self):
        if self.should_exit is False:
            self.should_exit = True


class FooBarWidget(FooWidget):
    def __init__(self):
        self.ctx = zmq.Context.instance()
        self.publisher: zmq.Socket = self.ctx.socket(zmq.PUSH)

        self._init()

    def _init(self):
        def worker_thread_start():
            FooWidget.__init__(self)
            self.run()

        worker_thread = Thread(target=worker_thread_start, daemon=True)
        worker_thread.start()

    def bar(self):
        pass

    def close(self):
        super().close()
        self.publisher.close()


# Will randomly fail with `AttributeError: 'FooBarWidget' object has no attribute 'should_exit'`.
# Sleeping a little will "fix" it.
def test_foobar():
    f = FooBarWidget()

    with closing(f):
        # time.sleep(0.01)
        assert False