Unit Testing - test for file count and folder size

I have homework JS code to check every week.
I have tests for JS logic, but i also has a requirement for overall size and file quantity. So i was wondering is there any possibility to write tests (i assume mocha - because it runs on node, and has access to FS) for folder size and file count in folder (also has a limit)?

I have no experience in Mocha or Node, so should i dive deeper?