Test Optional Dependencies

[lorenzofavaro]

Description

This PR adds a test module for optional dependencies just for the core version of PyBaMM.
Important changes made:

• Remove anytree from test_import_optional_dependency (it's a required dependency, not an optional one).
• Make pandas a required dependency. It is actually installed along with xarray (currently a required dependency).
  To verify it:

   python3.11 -m venv venv # create new environment
   source venv/bin/activate # access it
   pip install xarray # install xarray
   pip list # show installed packages

  This step avoids finding it among the optional dependencies when we parse them using importlib.metadata('pybamm'). Since the core version of pybamm also installs it, the test to check that it does not contain optional dependencies would fail.
• Add a separate test module. The reason for this is that the test TestDependencies.test_optional_dependencies as implemented, does not use the function import_optional_dependency* and conceptually does not verify that a unit function is working correctly. It is checking that in the core version of pybamm we are not installing more dependencies than we expect. Moreover, it does not have to be inside a module with filename test_* because it would always be executed in any test session. Please, tell me what you think about this and if you suggest any alternatives.
• Add a separate job to the test_on_push.yml workflow that launch it with just the core pybamm installation.

*If I'm not wrong, we cannot use import_optional_dependency because distribution packages extracted from importlib.metadata do not necessarily have a 1:1 mapping with import packages, as per documentation:

Important: These are not necessarily equivalent to or correspond 1:1 with the top-level import package names that can be imported inside Python code. One distribution package can contain multiple import packages (and single modules), and one top-level import package may map to multiple distribution packages if it is a namespace package. You can use package_distributions() to get a mapping between them.

Fixes #3865

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.60%. Comparing base (8056d22) to head (4c52b2d).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3892      +/-   ##
===========================================
- Coverage    99.60%   99.60%   -0.01%     
===========================================
  Files          259      259              
  Lines        21273    21268       -5     
===========================================
- Hits         21189    21184       -5     
  Misses          84       84              

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[agriyakhetarpal]

Thanks, @lorenzofavaro – please do not mind the earlier, hasty review that I had put in. This looks good to me barring a few required changes. Some of them, such as those for refining CI can be considered for future PRs, not this one.

[agriyakhetarpal]

This looks great @lorenzofavaro, thank you! Approving from my end with one small comment. If no one has any additional comments, we can merge.

[agriyakhetarpal]

@all-contributors please add @lorenzofavaro for code, tests

[allcontributors]

@agriyakhetarpal

I've put up a pull request to add @lorenzofavaro! 🎉