inspect.iscorutinefunction() returns False for unittest.mock.AsyncMock instances

[moriyoshi]

BPO	40573
Nosy	@moriyoshi, @1st1, @lisroach, @tirkarthi, @iritkatriel

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-05-09.03:14:11.981>
labels = ['3.8', 'type-bug', 'library', '3.9', '3.10']
title = 'inspect.iscorutinefunction() returns False for unittest.mock.AsyncMock instances'
updated_at = <Date 2020-08-25.16:22:34.440>
user = 'https://github.com/moriyoshi'

bugs.python.org fields:

activity = <Date 2020-08-25.16:22:34.440>
actor = 'iritkatriel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-05-09.03:14:11.981>
creator = 'moriyoshi'
dependencies = []
files = []
hgrepos = []
issue_num = 40573
keywords = []
message_count = 3.0
messages = ['368497', '368498', '375886']
nosy_count = 5.0
nosy_names = ['moriyoshi', 'yselivanov', 'lisroach', 'xtreak', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40573'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[moriyoshi]

inspect.iscoroutinefunction() returns False for unittest.mock.AsyncMock instances while asyncio.iscoroutinefunction() returns True.

>>> import unittest.mock
>>> import inspect
>>> import asyncio
>>> inspect.iscoroutinefunction(unittest.mock.AsyncMock())
False
>>> asyncio.iscoroutinefunction(unittest.mock.AsyncMock())
True

Confirmed with 3.8.2 and 3.9dev

[tirkarthi]

I couldn't reproduce the change in result for consecutive calls on master branch. They should return the same value.

./python   
Python 3.9.0a6+ (heads/master:7f7e706d78, May  9 2020, 04:00:36) 
[GCC 7.5.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import unittest.mock
>>> import inspect
>>> import asyncio
>>> inspect.iscoroutinefunction(unittest.mock.AsyncMock())
False
>>> inspect.iscoroutinefunction(unittest.mock.AsyncMock())
False
>>> inspect.iscoroutinefunction(unittest.mock.AsyncMock())
False

[iritkatriel]

The two implementations of iscoroutinefunction are implemented differently:

in inspect:
def iscoroutinefunction(obj):
"""Return true if the object is a coroutine function.
Coroutine functions are defined with "async def" syntax.
"""
return _has_code_flag(obj, CO_COROUTINE)

and in asyncio:
def iscoroutinefunction(func):
"""Return True if func is a decorated coroutine function."""
return (inspect.iscoroutinefunction(func) or
getattr(func, '_is_coroutine', None) is _is_coroutine)

originally the asyncio version had only the _is_coroutine check:
f951d28

the inspect check was added later.

See also bpo-28703, where the asyncio version was fixed to handle mock objects. Looks like the inspect version needs to be fixed as well.