TST: Adding tests for validating  DataFrame.__setitem__ and .loc behavior
- [ ] closes #xxxx (Replace xxxx with the GitHub issue number)
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Following up from #61804, adding tests to test_api.py to validate the DataFrame.__setitem__ and .loc assignment from Series
@WillAyd Since I have you, last follow up from the https://github.com/pandas-dev/pandas/pull/61804, Should we keep these tests? 

Last convo on this issue regarding tests was here: https://github.com/pandas-dev/pandas/pull/61804#discussion_r2193379353 I appreciate adding tests but I think this PR is superfluous - these cases are definitely covered in the existing code > I appreciate adding tests but I think this PR is superfluous - these cases are definitely covered in the existing code

Gotcha! Thanks for the insight. Closing this ticket.