How to mock asyncio coroutines?

Question

The following code fails with TypeError: 'Mock' object is not iterable in ImBeingTested.i_call_other_coroutines because I've replaced ImGoingToBeMocked by a Mock object.

How can I mock coroutines?

class ImGoingToBeMocked:
    @asyncio.coroutine
    def yeah_im_not_going_to_run(self):
        yield from asyncio.sleep(1)
        return "sup"

class ImBeingTested:
    def __init__(self, hidude):
        self.hidude = hidude

    @asyncio.coroutine
    def i_call_other_coroutines(self):
        return (yield from self.hidude.yeah_im_not_going_to_run())

class TestImBeingTested(unittest.TestCase):

    def test_i_call_other_coroutines(self):
        mocked = Mock(ImGoingToBeMocked)
        ibt = ImBeingTested(mocked)

        ret = asyncio.get_event_loop().run_until_complete(ibt.i_call_other_coroutines())

Answer 1

Since mock library doesn't support coroutines I create mocked coroutines manually and assign those to mock object. A bit more verbose but it works.

Your example may look like this:

import asyncio
import unittest
from unittest.mock import Mock


class ImGoingToBeMocked:
    @asyncio.coroutine
    def yeah_im_not_going_to_run(self):
        yield from asyncio.sleep(1)
        return "sup"


class ImBeingTested:
    def __init__(self, hidude):
        self.hidude = hidude

    @asyncio.coroutine
    def i_call_other_coroutines(self):
        return (yield from self.hidude.yeah_im_not_going_to_run())


class TestImBeingTested(unittest.TestCase):

    def test_i_call_other_coroutines(self):
        mocked = Mock(ImGoingToBeMocked)
        ibt = ImBeingTested(mocked)

        @asyncio.coroutine
        def mock_coro():
            return "sup"
        mocked.yeah_im_not_going_to_run = mock_coro

        ret = asyncio.get_event_loop().run_until_complete(
            ibt.i_call_other_coroutines())
        self.assertEqual("sup", ret)


if __name__ == '__main__':
    unittest.main()