gh-72889: remove redundant mock.Mock()._is_coroutine = False workarounds

[graingert]

these work-arounds were made redundant by python/asyncio#459

• Issue: Fix asyncio.iscoroutinefunction to handle Mock objects #72889

[graingert]

when asyncio.iscoroutinefunction was implemented as:

cpython/Lib/asyncio/coroutines.py

Lines 245 to 248 in 2f84144

	def iscoroutinefunction(func):
	"""Return True if func is a decorated coroutine function."""
	return (getattr(func, '_is_coroutine', False) or
	_inspect_iscoroutinefunction(func))

this meant

self.loop._add_reader = mock.Mock()
assert asyncio.iscoroutinefunction(self.loop._add_reader) is True  # mock objects have a truthy _is_coroutine attribute!
self.loop._add_reader._is_coroutine = False
assert asyncio.iscoroutinefunction(self.loop._add_reader) is False  # patching it works around the issue

however the implementation was changed to use a marker object:

cpython/Lib/asyncio/coroutines.py

Lines 16 to 23 in ec4745b

	# A marker for iscoroutinefunction.
	_is_coroutine = object()
	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)

and so now the _is_coroutine = False work-around is redundant:

self.loop._add_reader = mock.Mock()
assert asyncio.iscoroutinefunction(self.loop._add_reader) is False  # mock objects have an _is_coroutine but it's not the asyncio.coroutines._is_coroutine sentinel
self.loop._add_reader._is_coroutine = False
assert asyncio.iscoroutinefunction(self.loop._add_reader) is False  # it's still False so the workaround is redundant

[graingert]

I don't think this needs a news entry

[gvanrossum]

Since this just changes tests and the tests pass, I think this is okay.

[miss-islington]

Thanks @graingert for the PR, and @gvanrossum for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

[bedevere-bot]

GH-94934 is a backport of this pull request to the 3.11 branch.