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Example Code

import sys
import asyncio
import inspect
from unittest.mock import create_autospec, patch

print(f"Python version: {sys.version_info[:2]}") # (3, 12)

async def foo():
    pass

mock_autospec = create_autospec(foo)
print(asyncio.iscoroutinefunction(mock_autospec)) # True
print(inspect.iscoroutinefunction(mock_autospec)) # False

with patch('__main__.foo', autospec=True) as mock_foo:
    print(asyncio.iscoroutinefunction(mock_foo)) # True
    print(inspect.iscoroutinefunction(mock_foo)) # False

Description

This issue is related to a known Python bug that was fixed in Python 3.13 but has not been backported to earlier versions: python/cpython#94924
As a workaround for versions prior to Python 3.13, we could consider using conditional imports based on the Python version:

if sys.version_info < (3, 13):
    from asyncio import iscoroutinefunction
else:
    from inspect import iscoroutinefunction

Operating System

Windows

Operating System Details

No response

FastAPI Version

0.116.1

Pydantic Version

2.10.6

Python Version

Python 3.11.3

Additional Context

No response