Add sparse matrix and scaling tests

[ewu63]

Purpose

Add a few tests, partially addresses #256.

Expected time until merged

A few days

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Checklist

• I have run ruff check and ruff format to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[codecov]

Codecov Report

❌ Patch coverage is 0% with 78 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.22%. Comparing base (20cfa02) to head (c294b87).

Files with missing lines	Patch %	Lines
tests/test_optProb.py	0.00%	78 Missing ⚠️

❌ Your patch check has failed because the patch coverage (0.00%) is below the target coverage (50.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #486       +/-   ##
===========================================
- Coverage   82.99%   54.22%   -28.78%     
===========================================
  Files           1        1               
  Lines         147      225       +78     
===========================================
  Hits          122      122               
- Misses         25      103       +78     

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[marcomangano]

Thanks a lot for doing this! Just a few very minor points below

[marcomangano]

Thanks for the comments, LGTM

[A-CGray]

Can you add docstrings like this, that explain what the test is checking, to all these new tests? I usually find LLMs are pretty good at writing them, especially if you tell them to use the Given-When-Then style.