Would add some fixed test cases for invalid board - type 2, or make them occur more in random tests.

I see solutions that don't count with them and they can still get through on luck

This is https://leetcode.com/problems/container-with-most-water/ which is a direct copy of another site which isn't allowed I'm afraid.

Please see:

https://docs.codewars.com/authoring/guidelines/kata

"Do not use problems from other sites, unless it's allowed by that site's licensing policy and/or terms of use. Explicitly give appropriate credit if your kata is based on, or inspired by, someone else's work."