Add tests to help keep tox and github CI configurations approximately in sync

[bwhmather]

No description provided.

[github-actions]

Pull Request Test Coverage Report for Build 4813998588

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 98.225%

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Totals
Change from base Build 4813893877:	0.0%
Covered Lines:	1273
Relevant Lines:	1296

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💛 - Coveralls

[jgberry]

Wow, now we have tests for our tests. This is getting very meta indeed 😆 I think this does address some of my concerns with maintainability, although I question whether or not there is a better way to do this. I'm not aware of what that better approach would look like though, so at least for the time being, this will do.

[cgahr]

I think the issue is that there are 2 different ways to test the code, one using tox, the other using github actions. I think one of those should go and then we indirectly loose the duplication.

My proposal would be the following:

• all linters (black, isort, pylint, pyflakes, maybe mypy) go into pre-commit.
• we add a new github ci that runs pre-commit
• we add proper pytest configuration to test the code locally with the installed python version
• we run a matrix test for different OS and different python versions using github ci (as it is right now)

Basically this boils down to removing tox.

Alternatively, we could use https://github.com/ymyzk/tox-gh-actions to run tox using github actions.

[bwhmather]

Internet points will be awarded for tests that verify that these tests work. Config file parsing probably a good candidate. :D

[bwhmather]

Merging this one. Have raised an issue so that we can continue this discussion without comments disappearing as work is done: #87