Mutating the input should have no effects now
Yes, you're right. I used Array#shift with the input array, that's a bad thing.
Copying solved the issue. Thanks!
You are altering the list used by the test. Try to work on a copy or to not use destructive operation like python's pop.
If the solution alter the list (for exemple, in python, names.pop(0)), randoms test will fail. Test should provide a copy of the list when it make sense.