Example for mocking async context managers

asyncio-mock-example.py

import pytest
import aiohttp
import asyncio

from asynctest import CoroutineMock, MagicMock, patch


# Example Code

async def fetch(session, url):
    async with session.get(url) as response:
        return await response.text()

async def main():
    async with aiohttp.ClientSession() as session:
        html = await fetch(session, "http://google.com")
        print(html[:50])



# Example Test
@patch('aiohttp.ClientSession.get')
@pytest.mark.asyncio
async def test_fetch(mock_get):
    from example import fetch

    # in this case the result must be a coroutine mock
    # see: https://stackoverflow.com/a/48762969
    mock_get.return_value.__aenter__.return_value.text = CoroutineMock(side_effect=["custom text"])

    async with aiohttp.ClientSession() as session:
        result = await fetch(session, "http://example.com")

    assert result == "custom text"


if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

Thanks very match!!!

mock_get.return_value.__aenter__.return_value.text = CoroutineMock(side_effect=["custom text"])

it is help to test async context manager in function

Awesome thanks!