I ran across this answer which gives no code review feedback only how to write unit tests. If there were some unit tests provided, then they would be fair game for a code review also. In this case it seems more like a tutorial on how to write unit tests rather than specific review feedback for the code provided.
Is this answer on-topic?
The "on-topicness" for answers is not nearly as clear-cut as for questions (and even that has plenty of grey areas). The very first sentence, on its own, is enough to make it a valid code review: "First the good: your code provides a testable function."
Abusive answers, or answers which do nothing more than provide links, or an alternative solution without critiquing the OP code in any way, are about the only things in answers that can be "off-topic"....
anything else is dealt with by voting. If you don't like an answer, or it does not add value to the site, or the OP, then down-vote it, otherwise, if it is great, provides good insights, then up-vote it.
If enough people downvote an answer it sort of disappears in to obscurity anyway.
which gives no code review feedback only how to write unit tests
Oh? Please take another look at the result posted in that answer. It's pointing out failing edge-cases in a very constructive (although some might find it too succinct) manner. It's using the OP's approach to point out problems OP missed. That, is teaching done right. Identify the knowledge of your student and use it to further the knowledge on the specific problem.
It may not fit your style, but that answer is definitely a review. And not a shabby one either.
