Happy Christmas to you too :-) My sympathies for your heavy lockdown over Christmas. We're fortunate in New Zealand that we're a small island nation at the bottom of the world with a good government that has managed to eliminate covid, although there could be an outbreak at any time.
Without your prototype I can't check exactly what you're doing but I'm almost certain that the problem is that the "Is combinator" checkbox is checked in your prototype. Since the template is a per-test template not a combinator template, this will result in the TEST variable being undefined. You should uncheck it.
I attach an exported version of your question that uses your template within a customised question rather than as a question prototype. In its present form it's not usable because your support module generates random data so the output is non-deterministic, but it does at least run and generate plausible output. I suggest you steer clear of using randomisation until you have more familiarity with CodeRunner and its randomisation capabilities.