mocha cannot create an instance of my function

Question

Just starting out with mocha and cannot for the life of me figure out why it thinks Helper is undefined at the indicated line/columns below:

test.js

var assert = require('assert'),
    helper = require('../src/js/helper.js');
describe('helper', function() {
    describe('#parseValue', function() {
        it('should return number of minutes for a properly formatted string', function() {
            assert.equal(1501, (new Helper()).parseValue('1d 1h 1m', 'when'));
                                ^^^^^^^^^^^^
        });
    });
});

helper.js

(function(exports) {

    'use strict';

    function Helper(opts) {

        this.opts = opts || {};

        /**
         *  Parse a value based on its type and return a sortable version of the original value
         *
         *  @param      {string}    val     input value
         *  @param      {string}    type    type of input value
         *  @returns    {mixed}     sortable value corresponding to the input value
         */
        this.parseValue = function(val, type) {

            switch (type) {

                case 'when':
                    var d = val.match(/\d+(?=d)/),
                        h = val.match(/\d+(?=h)/),
                        m = val.match(/\d+(?=m)/);
                    if (m)
                        m = parseInt(m, 10);
                    if (h)
                        m += parseInt(h, 10) * 60;
                    if (d)
                        m += parseInt(d, 10) * 1440;
                    val = m;
                    break;

                default:
                    break;

            }

            return val;

        };

    }

    exports.helper = Helper;

})(this);

I wrote a quick test in the browser without mocha to ensure my helper.js functions were accessible and it worked fine, so I really am at a loss. I am running this directly on my server by calling mocha from the command line in my directory.

Answer 1

You never define Helper in test.js—only helper on this line:

var helper = require('../src/js/helper.js');

Use the lower case helper that you defined.

---

By the way, you might want to change your exports line in helper.js from this:

exports.helper = Helper;

To this:

exports.Helper = Helper;

Then use helper in test.js like so:

assert.equal(1501, (new helper.Helper()).parseValue('1d 1h 1m', 'when'));

Or just do something like this:

var Helper = require('../src/js/helper.js').Helper;