test_configs file is missing docstrings

[JinHuang0101]

All methods in the test_configs.py file are missing docstrings and in-line comments. Adding docstrings and inline comments to the file will help contributors quickly understand and build upon the test code.

[JinHuang0101]

I'd love to work on this issue and complete the documentation for this file.

[gvwilson]

thanks @JinHuang0101 - if you would like to prepare a PR we would be happy to prioritize review.