Addition of isInstance test of BackendSerial

[talagayev]

Fixes #4657

Changes made in this Pull Request:

• Addition of test_instance_serial_backend to test_base.py to check that the function works and the instance is correct

Currently I just create a variable of BackendSerial for serial_backend , which I use in FrameAnalysis(u.trajectory).run to display that it runs with the backend=serial_backend and also then check the correct instance of serial_backend

I wasn't sure here if I should check the instance of backend of the run() in FrameAnalysis(u.trajectory).run(backend=serial_backend), since then I would need to modify the code to get the instance of backend from run()

PR Checklist

• Tests?
• Docs?
• CHANGELOG updated?
• Issue raised/referenced?

Developers certificate of origin

• I certify that this contribution is covered by the LGPLv2.1+ license as defined in our LICENSE and adheres to the Developer Certificate of Origin.

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📚 Documentation preview 📚: https://mdanalysis--4773.org.readthedocs.build/en/4773/

[pep8speaks]

Hello @talagayev! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2024-10-29 12:14:35 UTC

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.63%. Comparing base (e776f12) to head (8a54898).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4773      +/-   ##
===========================================
- Coverage    93.66%   93.63%   -0.03%     
===========================================
  Files          177      189      +12     
  Lines        21726    22792    +1066     
  Branches      3052     3052              
===========================================
+ Hits         20349    21342     +993     
- Misses         930     1003      +73     
  Partials       447      447              

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[RMeli]

To me this test looks a bit self-referential. You are creating a backends.BackendSerial and then just checking that said object is indeed backends.BackendSerial. Could you please elaborate a bit more what is the intent here? I might be missing something...

[talagayev]

Yes the idea is the checking of this part of the code:

https://github.com/talagayev/mdanalysis/blob/8a5489804d2b62c76f6909034b8a43cd6ff1a65d/package/MDAnalysis/analysis/base.py#L776-L780

but I was not sure if the Issue idea was to test assert that backends.BackendSerial runs as an input and assert the input, which is the current case or if the Idea is to test the backend in FrameAnalysis(u.trajectory).run

https://github.com/talagayev/mdanalysis/blob/8a5489804d2b62c76f6909034b8a43cd6ff1a65d/testsuite/MDAnalysisTests/analysis/test_base.py#L293-L298

So yes, looks confusing the pytest, since I am not sure which should be tested, that it works with backends.BackendSerial or the isinstance(backend, BackendSerial)

If it is the latter, then I would modify the pytest

my bad for making it a little bit confusing here 🙈

[RMeli]

Thank you for the clarification. To test the part of the code you linked, what I would do is to use pytest.raises to make sure an exception is thrown when the backend is not serial.

[talagayev]

Ah I see, yes that makes sense, I will then adjust the PR accordingly :)