Packaging and testing cleanups

[agronholm]

Mostly cosmetic simplifications and improvements in the testing and packaging setup.
Highlights:

• Use pytest-cov for test coverage
• Removed test_requirements.txt in favor of a testing extras (pip install -e .[testing])
• Added python_requires to packaging metadata
• Use Pathlib for reading file contents

[Tinche]

For the failing test, I suggest making tests/async_fixtures/test_async_gen_fixtures_35.py collectable only for 3.5 (the refactor removed async_generator as a test dependency, which I think is the right move).

[agronholm]

No, the accidental removal of async_generator as testing dependency was a mishap. I will add it back. Such generators must be usable from Python 3.6+ and should also be tested that way.

[Tinche]

I'd say 3.6+ should just use normal async generators, no?

[agronholm]

And if you're running 3.5 compatible code on 3.6?

[agronholm]

Let me rephrase: test code written for 3.5 should be runnable on 3.6 too, and the inclusion of async_generator in the test requirements ensures that the test suite covers this as well.

[Tinche]

Right, you have a point. I don't see the harm including it in the test requirements in any case.

[Tinche]

One last thing: I see you removed the metadata section from setup.cfg. Is the license file still being included in the wheel? I had an explicit request for this from a downstream repackager.

[agronholm]

I see no references to such functionality in setuptools or wheel. Nor have I seen this anywhere else. Can you point me to documentation that says this is a thing?

[Tinche]

Right, it's kinda obscure. Here's a link, search for 'metadata' inside: https://hynek.me/articles/sharing-your-labor-of-love-pypi-quick-and-dirty/

You can test it out yourself, wheels are zips. The license should be in there after python setup.py bdist_wheel.

[agronholm]

Seems like an undocumented option. I'll put it back.

[agronholm]

Note that the official wheel documentation says the following:

Older versions of bdist_wheel supported passing requirements in a now-deprecated [metadata] section in setup.cfg.

[Tinche]

Thanks!