(Comments REST API) User with "moderate_comments" can't update/delete comments

[meloniq]

Affected API: ​https://developer.wordpress.org/rest-api/reference/comments/#update-a-comment

Endpoints: POST /wp/v2/comments/<id> and DELETE /wp/v2/comments/<id>

Case: As a user with Contributor or Author role I'm not able to update/delete a comment that I previously added.

Due to a logical bug in the method check_edit_permission(), a users without the moderate_comments capability aren't able to update or delete own comments as the part of code which checks permission on individual comment is never reached.

Patch correcting mentioned above part has been attached to the ticket.

[meloniq]

Looking a bit more farther, the edit_comment capability fallbacks to edit_post cap, so users with lower roles are not allowed to update/delete own comments at all... but that's an topic for another ticket with expanding permissions to comment authors in the edit_comment cap... Actually that's already reported in #41037

[kadamwhite]

While it doesn't seem like the logic error here is strictly as-described in the original post, per the follow-up indicating the new comment to address the original described issue. However, this seems like a reasonable change to improve handling of comment editing for requests authenticated as moderator-level users.

In the absence of any active comments component maintainers I'm going to commit this for 5.3.

[kadamwhite]

Add basic unit tests to try to validate issue

[kadamwhite]

Adjust new tests to correctly test the condition being changed

[kadamwhite]

phpcbf

[kadamwhite]

After implementing tests, I successfully demonstrated that the condition this patch changes did not previously permit any moderate_comments users (not just the post author) from editing an existing comment, despite several places in core comments code where we treat moderate_comments as synonymous with admin-level privileges. I've added a test to validate that a user with moderate_comments is permitted to do just that.

[kadamwhite]

Editing title for better disambiguation from #41037

[kadamwhite]

In 46433:

REST API: Ensure users with "moderate_comments" capability may edit comments.

Props meloniq.
Fixes #47024.