I think the vast majority of kata require printing to make good sense out of error messages [...]. It would be an issue that could be raised almost everywhere.

That's what we get from inconsiderate authors and reviews. There's a general guideline about clear assertion messages specifically to address such cases, hopefully it will get enough attention.

On further investigation, they do produce exactly that message. :D

I think the vast majority of kata require printing to make good sense out of error messages, this wouldn't be any different to that, even when it says literally (actual) == (expected) is false. It would be an issue that could be raised almost everywhere. It would be really nice to have such output though. Sometimes I think tests should go through stdin and stdout instead of functions, making a lot of kata language agnostic with nice error messages for everyone...

Still, users (especially low level ones) can't get sh*t from such message. Actual form could depend on specific cases and organization of the test suite, but ideally it should look like "Invalid answer for n=11. Expected: XXXX, actual: YYYY" or similar.

Showing the input is more than most assertion messages around here do >.>
Wouldn't that tutorial be referring to messages that could potentially look like this:

The expression (actual) == (expected) is false.

Feedback is not wrong, but it's confusing. There's a mention of this problem in C authoring tutorial and tests should be fixed to use custom assertion messages.

Feel free to re-raise this as an issue.

Unclear what you're showing and what the language is.
My guess is that you failed some assertions, that you see this in the output window:

The expression (look_say(11)) == (21) is false.
The expression (look_say(1122)) == (2122) is false.

Nobody can tell you whether that is correct since you're not including what your function's result was.

But it tells you what the input is and what the expected output is, so you can test your function yourself to determine whether it did its job.

Suggestion: test your function yourself with those same testcases:

look_say(11)
look_say(1122)

"The expression (look_say(11)) == (21) is false. The expression (look_say(1122)) == (2122) is false." is this feedback wrong ? or i miss understand the kata !!

Just check out your error messages: error: use of undeclared identifier 'aa'

use a spoiler flag

Do not use a loop.

No problem.

thanks dude !!
Passed: 65 Failed: 2
Exit Code: 1
Expected: -486 Submitted: 481
i thought that the input would be a positif integer