[Python] Mock asyncio.sleep to be faster in unittest

I want to mock asyncio.sleep to shorten the delay, e.g. by a factor of 10, to speed up my tests while also trying to surface any possible race conditions or other bugs as a crude sanity check. However I cannot figure out, if sut.py and test.py both use import asyncio, how to patch sleep only in sut.py but not test.py. For example, if I run the following:

import asyncio
import pytest
from unittest.mock import Mock, AsyncMock, patch

@pytest.mark.asyncio
@patch("sut.asyncio.sleep")
async def test(mock_asyncio_sleep):
print(asyncio.sleep)


It prints an AsyncMock instance rather than the actual sleep function.

The issue is then I cannot simulate the sleep in test.py:

@pytest.mark.asyncio
@patch("sut.asyncio.sleep")
async def test(mock_asyncio_sleep):
async def fast_sleep(t):
await asyncio.sleep(t / 10)
mock_asyncio_sleep.side_effect = fast_sleep

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