Add Python 3.12 beta to test matrix

[harshil21]

To be merged after #3728

Things changed for us:

• Tests: Fix regex pattern match in test_picklepersistence: Remove new line in pickle error message python/cpython#31782
• Tests: Slightly better formatted error message for missing abstractmethods. The test also now uses __abstractmethods__ to dynamically get all defined abstract methods.
• app.create_task should not accept generators. See below post

[harshil21]

def gen():
    yield

await asyncio.create_task(gen())

does not work in python 3.12. Changing into an async def does not work either.

The 3.12 changelog notes:

"asyncio.iscoroutine() now returns False for generators as asyncio does not support legacy generator-based coroutines."

Does this mean we should drop support for generators in app.create_task too? Support for that was added in #3543 (comment).

Related code and PRs:

https://github.com/python/cpython/blob/main/Lib/asyncio/tasks.py#L106-L110
python/cpython#102749

[Bibo-Joshi]

Does this mean we should drop support for generators in app.create_task too?

Not for py 3.11-, as that would be a breach of our stability policy. We can think about deprecating it, but dropping support unannounced is a no-go.
For 3.12+, to stay in line with our stability poclicy, we should try to still support it + add deprecation notices. If there is no feasible workaround, we ofc don't have a chance.

[harshil21]

@Bibo-Joshi okay, now how do I specify different type hints for the coroutine parameter for different python versions? Should I just use a if sys.version_info.. : @overload def create_task(...) thingy?

and what kind of workaround do you suggest for py3.12+? I don't see any

[Bibo-Joshi]

@Bibo-Joshi okay, now how do I specify different type hints for the coroutine parameter for different python versions? Should I just use a if sys.version_info.. : @overload def create_task(...) thingy?

Sounds good if that works reasonably well. Don't know if it's possible to make only the overload part the content of the if clause or if you have to define the method twice

and what kind of workaround do you suggest for py3.12+? I don't see any

I don't have anything in mind TBH, haven't looked into it yet

[harshil21]

I double checked by running mypy in different python versions, and also checked if VSCode shows a type error when passing an (async) generator to app.create_task for py > 3.12.

[github-actions]

Hey! Looks like you edited the (optional) requirements or the pre-commit hooks. I'm just a friendly reminder to keep the additional dependencies for the hooks in sync with the requirements :)

[harshil21]

pre-commit.ci run