Note that Code Wars is for those Learning to Program all the way up to Experts. It should be considered bad practice to assume that anyone attempting a kata, especially an "easier" one, would know all programming best practices. Instructions are there for a reason and should be explicit.

That's probably something that should be in the instructions

all 11 of the kata tests pass, it's only the random ones that fail, all 200

All 200 Random failures look like :

Expected: '[]', instead got: '[['VUxATV', 'VsKkvL VGR osu LSVY chE'], ['VUxATV VsKkvL', 'VGR osu LSVY chE'], ['VUxATV VsKkvL VGR', 'osu LSVY chE'], ['VUxATV VsKkvL VGR osu', 'LSVY chE'], ['VUxATV VsKkvL VGR osu LSVY', 'chE']]'

but all Samples are green

All the random tests are failing, sample tests work fine but the random tests are expecting and empty array