NodeJS has a lot of different package for unit testing. I'll investigate more when I can. For now, I like this one:

Tape

It's pretty simple.

For example:

var hello = function() {
  return "Hello World!";
}

const test = require('tape');

test("unit tests", function(t) {
  t.equal(hello(), "Hello World!", "- hello() test");
  t.end();
});

Outputs:

TAP version 13
# unit tests
ok 1 - hello() test

Basic usage

Testing for strings that match a RegExp
The tape.equal(a, b, msg) method checks for equality. Sometimes it is convenient to check for a RegExp instead. Just use tape.ok().

For instance:

var hello = function() {
  return "Hello World!";
}

const test = require('tape');

test("unit tests", function(t) {
  t.ok(/Hello/.test(hello()), "- hello() test");
  t.end();
});

Gives the same output as the previous example.