Ah nevermind, I was actually not covering an edge case.

@dem4ron do you remember how you resolved it? I am getting the same error, even though it seems to work fine on an other IDE.

Do you get the same error when running this test case locally in your IDE?

I modified the input field by creating a class, because it is simplier to me. could that cause the problem?

I am not sure what you exactly did, but remember that interface of your solution (name, parameters, return value) have to match to what tests expect because test suite calls your solution, so it has to know how.

Expected: '[\'a\', \'b\', \'c\', 1, \'1\', 2, \'2\', \'2\', 3, \'3\']', 
instead got: 
          '[\'a\', \'b\', \'c\', \'1\', 1, \'2\', 2, \'2\', 3, \'3\']'

Feedback is pretty clear here... Your chrome might be using different node version that handles sorting differently, IDK. I see in your code that your sort is incomplete, when elements are similar.

Anyway, your code not working is not a KATA issue! Please take your time to read this FAQ before raising issues.