Add async support

[pauloromeira]

Implement: #4

Hi @fabfuel ,

First of all, congrats for the lib!

This PR adds async support to it, but this change will drop python 2 support and some python 3 early versions.

I'm opening it now to kindly ask you some help for making this available for the majority of python versions and change setup / gh actions accordingly.

Thanks in advance!

[pauloromeira]

Hi @fabfuel!

Tests are now passing for: 3.7, 3.8, 3.9, 3.10, 3.11. Maybe it also works for Python 3.6 but unfortunately pytest-asyncio doesn't support 3.6, which is required for pytest to run async tests.

I know you might not like dropping support for versions 2.7, 3.5 and 3.6, but I believe usage can increase with async support. Specially since pybreaker, the most popular alternative, is not supporting async yet.

Two notes:

1. I slightly changed the fallback functionality for generators to make everything more consistent. Before it was possible to have a fallback function that was not a generator in this case. Well, if the fallback function is called implicitly, I believe it should match the same interface as the decorated function, not just its args. So I changed that, and now for every decorated function: if sync, the fallback must be sync; if generator, the fallback must be a generator; if async, the fallback must be async and if async generator, the fallback must be async generator - I added this information to the README.

2. The tests are now running, whenever applicable, for every supported function types: sync-function, sync-generator, async-function and async-generator (you can see it by running pytest with the -v flag). This is not only extending generators tests but reusing almost all existing tests for the asynchronous types.

I hope you like and decide to merge it!

Regards,
Paulo

[fabfuel]

Thanks a lot @pauloromeira! Sorry, I'm a bit behind as i had no time to fully review yet, but what I saw so far looks really good. I try to find time to also test it as soon as possible! 🙂

[fabfuel]

Sorry for the long delay @pauloromeira, I needed to prepare for parental leave and had very busy last weeks while currently not working in the Python universe, so I needed some time to get into the topic again. I also did not use Python async functions in production yet, so it's awesome, that you took care for adding the functionality 🙏

Thanks a lot for your PR, it's really well done. I highly appreciate your effort and the way how you integrated the async functionality into the existing library in an unobtrusive way (=without rewriting everything 😉).

The tests have been quite rewritten though, so I needed some time to test myself and get back into it. But finally I reviewed it and I'm happy to merge.

I will create version 2.0, I think this new ability deserves a new major version, especially also as we drop Python2 support.

Thanks a lot @pauloromeira!

[fabfuel]

Oh, that's a nice syntax, I did not know 🙂

[pauloromeira]

You're welcome, @fabfuel! Thank you for dedicating your time and effort to reviewing it. I appreciate your decision to proceed with the merge, despite the drop of support for Python 2.

Wishing you all the best in your journey of parenthood! 🎉