Switch to setuptools-scm for versioning

[hayderimran7]

Following other pytest projects like pytest-html,
that use setuptool-scm to manage version
pytest-dev/pytest-html@d9c0b87 .
It would be nice other projects follow the suit and
let setuptools-scm manage version of this project.

[Tinche]

Hi!

This looks interesting. I'm generally in favor, but I need to get some free time to read up on this and play around with it. :)

[nicoddemus]

For the record it works great, and will also solve #92 because setuptools_scm will add all versioned files to the package automatically.

[nicoddemus]

I've fixed the conflicts and adopted the strategy of writing a _version.py file so we can keep having the __version__ attribute in the package. 😉

[nicoddemus]

This also paves the way to automatic deployments using Travis, which are highly recommended. Let me know if I can help @Tinche!

[blueyed]

FWIW I think https://github.com/zsimic/setupmeta is even nicer.

[seifertm]

Rebased the PR to master and added setuptools_scm as dependency to the CI steps.

I also cloned my local pytest-asyncio git repo and and ran tox in a fresh virtualenv. Tox successfully picked up the dependency on setuptools_scm.

[codecov-commenter]

Codecov Report

Merging #37 (271edba) into master (41420cf) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #37      +/-   ##
==========================================
+ Coverage   95.43%   95.45%   +0.02%     
==========================================
  Files           2        2              
  Lines         219      220       +1     
==========================================
+ Hits          209      210       +1     
  Misses         10       10              

Impacted Files	Coverage Δ
pytest_asyncio/__init__.py	100.00% <100.00%> (ø)
pytest_asyncio/plugin.py	95.39% <0.00%> (+0.02%)	⬆️

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[asvetlov]

Looks good, please apply my tiny improvements before pressing the 'squash and merge' button.

[seifertm]

Without the pip install setuptools_scm in the testing job, tox didn't pick up the dependency on setuptools_scm correctly and the test run failed due to a missing _version.py file. After adding setuptools_scm to setup_requires in setup.cfg everything worked. This is also how pytest-xdist handles it. They define the dependency in setup.cfg, [1] but configure setuptools_scm in pyproject.toml [2].

[1] https://github.com/pytest-dev/pytest-xdist/blob/a1a6c77028d1c2215f2457482602d214f7f9f532/setup.cfg#L43
[2] https://github.com/pytest-dev/pytest-xdist/blob/a1a6c77028d1c2215f2457482602d214f7f9f532/pyproject.toml#L10-L11

[asvetlov]

Interesting. I thought that the single source of setuptools_scm dependency (pyproject.toml) should be enough.
Can live with this sort of duplication, sure!
Thanks for the double-checking.