Jasmine Headless vs In Browser

In the last couple projects, we’ve been using Jasmine for our Javascript testing. It’s been great. Tying that in with jasmine-headless-webkit has made our Javascript testing super fast for both development and our CI box.

One problem we’ve hit a couple times is differences between the real browser and the fake browser (headless-mode). For example: in the real browser, you can build an iframe with a src attribute and it will do the right thing.


However, if you run this through your headless tests, depending on where this code is executed, you may get errors like this from jQuery:

Fixture could not be loaded: spec/javascripts/fixtures/recipe_subnav.html
(status: error, message: NETWORK_ERR: XMLHttpRequest Exception 101)

or like this from the Jasmine framework:

Can't load file:///projects/myproject/specrunner.11688.html, the file may be broken.
Out of curiosity, did your tests try to submit a form and you haven't prevented that?
Try running your tests in your browser with the Jasmine server and see what happens.

Certainly, we could probably stub out a bunch of stuff to make this fly, but sometimes time is better spent pushing forward. To get around this, we wanted a simple way to check for the command line tests vs in browser tests. We added to our SpecHelper.js file:

var is_headless = function() {
  return (/jasmine-headless-webkit/.test(navigator.userAgent));

With this now in place, we can write tests like this:

describe('save scroll top cookie plugin', function() {
  beforeEach(function() {
  if(is_headless()) {
    it('it sets a cookie for scroll position', function() {
  it('does something else', function() {

With this setup, instead of missing tests because we’ve constructed a bunch of xit or xdescribe blocks, we can keep all the tests around, and simply skip those that don’t lend themselves to the specific situation (in-browser or headless).

It is not something that is used a lot, because we really strive to make tests which are universal, but in those special cases where we still may want a spec, this simple helper method works pretty nicely.