How to restrict some keywords or create one-line katas?

[cestxvcdim]

Hello, I'm facing a problem that I don't know how to limit a user's decision in using keywords. How, for example, are one-line tasks created? After all, the solution must be strictly one line, often with a character limit.

[zoeparker123]

You can enforce one-line katas or keyword restrictions by adding custom validation in the test suite. Most creators use simple regex checks to block certain words or to make sure the full solution fits within a strict character or line limit. It’s not a perfect system, but it’s the standard way Codewars handles these kinds of constraints.