How to test part of the code through Mocha.js?

Question

Software testing

I delve into js and testing, a question arose.
There is a script with different functions - script.js;
installed nodejs with chai.js and mocha.js;

var assert = require('assert');
describe('Cookies', function() {
    describe('viewCookie()', function() {
        it('should return undefined', function() {
            assert.equal(undefined, viewCookie());
        });
    });
});

how to properly run test of only one function from script.js? and how to access it correctly from the directory where the test is located?

Answer 1

'''mocha -g Cookies'''
The page says in the startup section