Recently, I got really tired of writing buggy code with prinths scattered everywhere to try and figure out what the hell was going on. So, I created a way to test your carts while they run. It gives you output on the command line that looks something like this:

Hopefully, it's not too difficult to installuse. I mimicked mocha's API at a high-level.
I'd love to hear what you think if anyone decides to try it out. You can also download the cart and take a look at the code for more info. There's fairly detailed documentation on Github:
https:github.comjozanzapico-test
Also, feel free to comment on this thread with questions or hmu on twitter. Cheers!