[TIP] Testing asynchronous method

Pere Martir pere.martir4 at gmail.com
Tue Oct 18 10:40:15 PDT 2011

I want to test if a callback is called within a predefined time. I am
surprised that I cannot find a simple solution on Internet.

I don't want to use Twisted Trial or tornado.testing but only Python
built-in unittest, is it possible ? I am developing  an asynchronous
library by TDD, and I don't want to depend on Twisted or Tornado.


Inspired by tornado.testing, I've implemented the following, which I
believe is not correct:

class TestMyAsync(unittest.TestCase):
    def setUp(self):
        self._stopped = False

    def _wait(self, timeout):
        if self._stopped: return True
        t = 0
        self._running = True
        while self._running:
            if not self._running:
            t += 1
            if t == timeout:
                return False
        return True

    def _stop(self):
        self._stopped = True
        self._running = False

    def test_async_method(self):
        def callback(ticket):
            self.assertEqual(ticket, 998)
        x = SomeAysncModules()
        x.async_method(999, callback)

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