Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
Mutating the input should have no effects now
Just tried ruby. Works fine.
The problem is most likely that you are modifying the input array.
If you are not, just post your code here (mark it as a spoiler) and i will look at it.
The test is definitely broken. I had the exact error.
Luckily, the broken inputs only showed up randomly. So I just kept pressing Submit until no broken input was passed. (It took me about 10 tries.)