993 progress: Convert test_catalog.py, test_layout.py and test_link.py to pytest

[teks]

Related Issue(s): #993

Description: Convert test_catalog.py, test_layout.py and test_link.py to pytest.

PR Checklist:

• Pre-commit hooks pass (run pre-commit run --all-files)
• Tests pass (run pytest)
• Documentation has been updated to reflect changes, if applicable
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.49%. Comparing base (542b9fb) to head (94b8acf).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1527      +/-   ##
==========================================
+ Coverage   91.47%   91.49%   +0.01%     
==========================================
  Files          54       54              
  Lines        7542     7571      +29     
  Branches      915      922       +7     
==========================================
+ Hits         6899     6927      +28     
  Misses        457      457              
- Partials      186      187       +1     

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