Set options in conftest.py instead of pytest.ini, install conftest.py

[johnomotani]

pytest.ini is ignored even if installed when testing the installed package with pytest --pyargs xbout. To get around this, set all options in conftest.py, and move conftest.py to the xbout/ directory so that it gets installed with the package.

Note, putting conftest.py in the xbout/ directory so that it is used both by tests/* and calc/tests/*.

[pep8speaks]

Hello @johnomotani! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers:

Comment last updated at 2020-10-06 18:28:16 UTC

[codecov-commenter]

Codecov Report

Merging #160 into master will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #160   +/-   ##
=======================================
  Coverage   76.89%   76.89%           
=======================================
  Files          11       12    +1     
  Lines        1913     1939   +26     
  Branches      431      437    +6     
=======================================
+ Hits         1471     1491   +20     
- Misses        291      296    +5     
- Partials      151      152    +1     

Impacted Files	Coverage Δ
conftest.py	76.92% <100.00%> (ø)

---

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[johnomotani]

I think this PR is an improvement, but I'd be glad to know of a neater way to do it... The problem it's trying to solve is to get pytest configuration set up in a way that works both: (1) after cloning the git repo, running pytest from either the top level, or in the xbout directory, etc; and (2) when xbout is installed as a package, running pytest --pyargs xbout.

The problems:

• pytest.ini isn't used by pytest unless it's in or above the directory where you run pytest, so the pytest --pyargs xbout version fails even if we installed pytest.ini with the package.
• conftest.py is used when installed locally (which is good for us), but is apparently a bit too local. (Just) putting conftest.py under the xbout/ directory so that it gets installed with the package means that running pytest at the top level of the git repo fails if you want to use the --long argument - apparently pytest parses the command line arguments before it loads the configuration from subdirectories.
• I don't know how to put conftest.py in the top level of the repo, but have it installed within the xbout package (this might be the neatest solution if it was possible).

The solutions:

• the pytest.ini problem is fairly simply fixed by doing all the configuration in conftest.py. It's ugly (there's a separate function call for every line that was in the pytest.ini) but it works.
• Put a conftest.py in the top level of the repo, and another one in the xbout/ directory. The one in the top level imports the setup functions that pytest uses from xbout/conftest.py, which is only slightly ugly. There's a new problem though, because like this running pytest from the top level of the repo (or actually anywhere in the git repo, apparently it manages to go back up to make the top level its root directory) means the setup gets imported twice and so pytest fails with an error about argument '--long' is already defined (or something roughly like that). To get around that, I've added some global flags to xbout/conftest.py which are False to start with and switched to True the first time the set-up functions are called and then stop the functions doing anything the second time they are called. Just to make this bodge lovelier, when I tried using the same flag for all three functions it didn't work, so there's a separate flag for each function.

So in summary, this solution seems to work. I think it's ugly, and I'd welcome a nicer way, but I think it's better to have some solution that makes --long work both in a cloned xbout git repo and for xbout installed as a package.

PS the original motivation for this is that the long marker was not being recognised by the conda-forge set up, so that was running the long version of the tests (which seems like an anti-social thing to do when they take ~30 mins to run, and the package was already tested by the Github action before being released).

[johnomotani]

I want to get xbout released on conda, so I'm going to merge this now. If anyone has nicer ideas, we can rework in another PR.