Document how to invoke pytest

[EwoutH]

This repository has a unusual structure with the extra layer directories of pydsol/core for both the src and tests folder. This makes running pytest non-trivial.

The docs state that can be pytest used:

pydsol-core/src/pydsol/core/__init__.py

Line 48 in 972b4ee

For the unit tests, pytest is used, potentially with pytest-cov to assess

But with all "standard" invokements of Pytest I get either an import error or a warning that no tests are found.

 ModuleNotFoundError: No module named 'pydsol'

With this directory structure, which command needs to be ran from which folder for pytest to work?

[averbraeck]

Good point. I copied the structure from several other Python projects, but it can probably be streamlined better I will see how I can improve it! Tips are always welcome.

Second point: The readthedocs pages still lack a good description how to install the project locally on your computer such that the module tests, coverage, demos, and code run best.

[EwoutH]

I think the big question is if this repository will include other components than the core.

If not, an easy fix would be to flatten the directory to src/pydsol_core and test/pydsol_core.

Best practice is to even don't include a src folder for the functional code. That would result in having pydsol_core and test/pydsol_core.

Your library does not belong in an ambiguous src or python subdirectory.

You could even consider dropping de _core suffix completely, and just call it pydsol. pydsol is still available on PyPI btw.

I could create a PR with these changes, if you want.

[EwoutH]

I created a PR with a possible refactor and CI implementation which follows best practices and works easily with CI: #2