Add CI workflow to check test coverage

[AdityaGupta716]

Closes #55

Adds a workflow to check test coverage on every push and pull request using Coverage.py.

Changes:

• Added check_coverage.py script that runs coverage report and fails if coverage is below a predefined threshold (currently set to 70%)
• Added check-coverage.yml workflow that runs all unit tests with coverage and calls the script to check the threshold

The threshold can be adjusted in check_coverage.py as the codebase grows.

[AdityaGupta716]

@MakisH @IshaanDesai, plz review! The threshold is currently set to 70% in check_coverage.py .if u want smthing different let me know.

[precice-bot]

This pull request has been mentioned on preCICE Forum on Discourse. There might be relevant details there:

https://precice.discourse.group/t/gsoc-2026-aditya-gupta/2773/1

[IshaanDesai]

@AdityaGupta716 can you please take a look at the CI output of the test coverage workflow? It seems like the workflow got stuck.

[AdityaGupta716]

@IshaanDesai hi, fixed the issue the workflow was hanging because unittest discover was picking up the parallel tests (test_adaptivity_parallel.py, test_global_adaptivity_lb.py) which need MPI to run. changed it to run each test file explicitly instead — same approach as the existing run-unit-tests.yml. Also current coverage is around 22%, so the 70% threshold might need adjusting , happy to change it to whatever you think fits!

[IshaanDesai]

Good work so far! I am surprised that the test coverage is not 70%, though I perceive it as having a certain value. The CI log, however, shows 0% test coverage, which seems definitely incorrect. Can you please take a look at what is going on?

[AdityaGupta716]

hi @IshaanDesai fixed the 0% coverage issue! The problem was the .coverage file wasn't being found correctly. The workflow now runs all serial and parallel unit tests with mpirun and combines the results, giving a real coverage of ~61%. I've set the threshold to 60% for now plz review and let me know if you think it should be different

[IshaanDesai]

@Snapex2409, to increase test coverage, some tests on things that you recently implemented have been added. Can you please go over them to ensure that they make sense?

[Snapex2409]

Overall, nicely done. With the requested changes, coverage should also increase a bit.

[Snapex2409]

Just the small refactory, then we should be ready to merge in my opinion.
And good thinking to mock the connection here 👍

[AdityaGupta716]

@Snapex2409 nah no reasons, moved it up