get version without importing

[javierggt]

Description

This removes a hack in version.get_version. Instead of importing a partially loaded module, use importlib.util.find_spec

Testing

• Passes unit tests on MacOS, linux, Windows (at least one required), although the relevant parts are not tested.
• Functional testing:
  • run python setup.py --version on a clean/dirty package git directory (without defining PYTHONPATH)
  • defined PYTHONPATH pointing to a dirty git directory, then python -c 'import proseco; print(proseco.__version__)'
  • running testr using this module, including a few other packages. Output seemed fine.

[jeanconn]

Great. I thought we had already been down this road and it didn't work for our use case, but I must be misremembering.

[javierggt]

well, we discussed this hack before, but I don't remember seeing importlib.util.find_spec then.

[taldcroft]

Looks good to me, very glad this appears to be working. The goal was always import-free versions.

I don't recall discussing this particular importlib function and I'm guessing we would have gone down that path had it been in the fray.

[javierggt]

After much fiddling and puzzling... my issue was a stray egg directory within my git local copy. It was left from a time when I did pip install -e .. For some reason I still do not understand, get_version was failing when running within testr, because importlib.util.find_spec was getting one path and pkg_resources.get_distribution was getting the other. I have not been able to reproduce it again.

[javierggt]

I will merge this PR.