Move Python test suite

[ischoegl]

Changes proposed in this pull request

• Move Python test suite out of Python module.
• Redirect output of test_convert.py::yaml2ckTest to work folder

If applicable, fill in the issue number this pull request is fixing

Closes #1258

If applicable, provide an example illustrating new features this pull request is introducing

After the proposed changes

$ pytest test/python
[...]
$ pytest test/python/test_onedim.py::TestDiffusionFlame::test_mixture_averaged
[...]

just works.

Checklist

• The pull request includes a clear description of this code change
• Commit messages have short titles and reference relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• Style & formatting of contributed code follows contributing guidelines
• The pull request is ready for review

[speth]

Thanks for making these changes, @ischoegl. I was pleased to see that this change fixes an issue I had been experiencing, where pytest's fancy introspection didn't work and wasn't able to show the values of the arguments of assert X == Y when the assertion failed.

I have two suggestions. First, if you add a test/python/pytest.ini file with the contents

[pytest]
pythonpath = ../../build/python

you will be able to run pytest test/python and variants directly from the root of the repository, without needing to set the PYTHONPATH (or accidentally running the tests from a previously-installed copy of Cantera). I also found that this let me set up integration with VS Code, which I think will be really nice to use.

Second, I'd like to suggest squashing some of the commits here that are not logically separate. For example, moving the test suite and fixing the integration with SCons. Changes like could lead to annoying errors while using git bisect in the future, where trying to run the tests with this intermediate commit just doesn't work. I think the same concern may be applicable to some of the commits in #1352.

[ischoegl]

@speth ... thank you for the review. Especially your comment about pytest.ini is valuable, as I did run my tests for pytest after checking that README.txt installs correctly (which presumably shadowed some issues that would arise without running scons install first). I am also happy that this PR appears to resolve some issues that you have been experiencing. At this point, I confirmed that running

$ pytest test/python

works after removing previous installs via scons uninstall.

Per suggestion, I also squashed commits - thus far, when committing, I was usually more concerned about keeping steps separate so I can trace back easily, but your point about git bisect is well taken.

[speth]

Checking out just the first commit here does not build, with the error:

scons: *** [build/python/dist/Cantera-3.0.0a2-cp310-cp310-macosx_11_0_arm64.whl] Explicit dependency `build/python/cantera/test/README.txt' not found, needed by target `build/python/dist/Cantera-3.0.0a2-cp310-cp310-macosx_11_0_arm64.whl'.

And as expected, running scons test with just the first two commits results in a bunch of pollution in the test/data directory.

So I'd like to suggest squashing at least the first of those commits, and possibly the second as well.

[ischoegl]

@speth ... I reordered the commits, so they now all build individually. The 'pollution' issue actually goes back to #1286, but was not apparent as it was polluting the build folder. I applied that fix - which I believe is completely unrelated to the main point of this PR - first.

[speth]

Thanks, @ischoegl. I think this is good to go.