Done, thanks for the heads-up :D

Please change var copyRandArr = randArr; to var copyRandArr = randArr.slice(); because otherwise the random tests are still vulnerable to input parameter modification.

glad it worked eventually!

Random tests have been modified to avoid exploit mentioned above. Issue resolved.

Thanks for the error report, I'll modify the random tests to avoid this exploit.

Proof of concept exploiting this issue posted as a secondary solution.

Updated the issue to reflect what is really going on.

I'll try to post a solution that illustrates this.

For clarity: http://i.imgur.com/06lYbs5.png

I don't know that it was cheating, but now that I look back on this, I have a feeling I was just modifying the test functions' output and not the test input.

This is probably the punishment for cheating ;)

I'm running a test with a specific approach that does not modify countdown, but to put it plainly, I'm able to manipulate the output before the test.
However, I receive the following failure:

"Expected: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, Zero!, instead got: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, Zero!"

As far as I can tell, these strings match.

Must have been a server issue. I tried the same code again and it worked fine both in test and submit.

My solution seems to pass the test run, but when I go to submit I receive this error:

[eval]:15 before = global.before, after = global.after;Test.describe("Basic tests",_=>{
^ SyntaxError: Unexpected token > at Object. ([eval]-wrapper:6:22)
at
at evalScript (node.js:536:25)
at startup (node.js:80:7)
at node.js:906:3

The description definition was not in the default test case for this kata when I loaded it. If I wrap the test loop in it, I still receive the same error.

What am I doing wrong?