JSDOM function does not finish

Question

Please help me understand what is wrong here:

Here is my js code (simplified to isolate the minimal code required to demonstrate the problem):

'use strict';
var jsdom = require('jsdom');
describe('desc', function () {
    it('should', function () {
        function uploadURL(callback) {
            jsdom.env({
                url: "http://digg.com",
                done: function (errors, window) {
                    console.log("inside");
                    callback("abc");
                }
            });
        }

        uploadURL(function(x){
            console.log("returned " + x);
        });
    });
});

Here is my command line:

node_modules/mocha/bin/mocha tests/test.js

When I run the above script, I'm getting the following output:

  desc
    ✓ should (196ms)
  1 passing (204ms)

Once I remove the jsdom part and run only the part of the uploadURL() that contains console.log and callback, I get this back:

desc
inside
returned abc
    ✓ should
  1 passing (5ms)

Seems like the jsdom part is not get executed before the script ends. Why is this and how can this be worked out?

Thank you!

Answer 1

Because it's asynchronous. To test an asynchronous function with Mocha, you accept the callback Mocha's it provides, and call it when the async is done:

'use strict';
var jsdom = require('jsdom');
describe('desc', function () {
    it('should', function (done) {
    //                     ^---------------------- accept the callback
        function uploadURL(callback) {
            jsdom.env({
                url: "http://digg.com",
                done: function (errors, window) {
                    console.log("inside");
                    callback("abc");
                }
            });
        }

        uploadURL(function(x){
            console.log("returned " + x);
            done();                            // <=== Call it
        });
    });
});

This is covered in the Mocha documentation here .