Thanks for the feedback. We'll rethink & rework this.

Don't use CW for testing your group of people if you can't put up something that meets the quality standards. As soon as something is published it becomes CW material and hence is subjected to CW quality standards.

Why can't you just send them existing katas? What are you trying to teach them anyway?

Specs promise string arguments. Testing is done on nulls as well, and it's unspecified what value should be returned for that.

If you want to somehow cater for callers not passing [ enough ] arguments, you should be testing with undefined, not null ( so default arguments would work. on null, they don't ).

1 - I do not understand.
2 - You did not have to publish this kata. If you have the link, you can find a Draft kata ( looking at your Authored kata also works, so if you know the author's username, you don't even need the link ).
3 - Please teach your "group of new JS learnings" ( ?!? ) the correct way of writing kata. That would include example tests, random tests, and not writing kata that shadow a native method, but wrong.
4 - You don't want to know how many points this cost you. Yes, bad ratings and issues actually cost you points.

The kata is apparently published.

FYI. I realize that this is similar to another Kata. However, this is being used as a test for a group of new Javascript learnings to help us structure future kata. This kata will be deleted by 4/9/2019. Thanks for your understanding while we conduct this experiment.

Thanks for the feedback on this. I was using this problem to gain experience creating kata. I've unpublished it so it doesn't pollute the system.

Obvious duplicate (this for example).