You can get some info from tests by printing to console: https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution#how-can-i-see-which-input-causes-my-solution-to-fail

Since somewhat recently I've been trying to promote a bit stricter policy regarding explicit, clear assertion messages, and it seems to gain some traction among authors and translators. Unfortunately it's not as widespread yet as I'd like to, and some testing frameworks do not even allow for it :( In such cases, print-debugging can come helpful.