BUG: String[pyarrow] comparison with mixed object

[jbrockmendel]

• closes BUG (string dtype): comparison of string column to mixed object column fails #60228 (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations 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.

Didn't add a whatsnew note since I'm not sure if the bug is in a released version cc @jorisvandenbossche ?

[jorisvandenbossche]

Looks good!

Didn't add a whatsnew note since I'm not sure if the bug is in a released version cc @jorisvandenbossche ?

It's also fixing a bug in the existing nullable string dtype, and we are generally noting bug fixes for the new str dtype as well in the 2.3.x whatsnew. I am planning to backport this, so you can add a note there.
(if it would only have been for the new dtype and targetting 3.0, it would indeed not need a whatsnew note)

[jorisvandenbossche]

Maybe move this to pandas/tests/arrays/string_/test_string.py? (in general this file only contains the generic extension tests, not string-specific ones)

[jorisvandenbossche]

(although it is not actually that string specific, generally all of our dtypes should do this comparison to mixed object dtype? So we could also make this a base extension test. But let's do that later, that might involve more fixes in other (test) EAs which doesn't need to be backported)

[jbrockmendel]

i started a branch this morning that adds a tests.arithmetic.test_string file. if this is merged, i'll move this test in that branch too

[jbrockmendel]

Are we good here? I'd like to follow up with the branch mentioned about refactoring string arithmetic tests.

[jorisvandenbossche]

Thanks @jbrockmendel!

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.3.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 4ee17b39893e20483b6f778ec83384faa39bdd88

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #62424: BUG: String[pyarrow] comparison with mixed object'

4. Push to a named branch:

git push YOURFORK 2.3.x:auto-backport-of-pr-62424-on-2.3.x

5. Create a PR against branch 2.3.x, I would have named this PR:

"Backport PR #62424 on branch 2.3.x (BUG: String[pyarrow] comparison with mixed object)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[jorisvandenbossche]

Manual backport -> #62504