Using Karma to test StealJS


Is there an example anywhere of using Karma to test a StealJS app?


Hey blink1073, unfortunately I don’t know of an example. Most of our projects use Testee and not Karma. However setting up Karma with Steal should be very similar to how it is used with RequireJS:

I think the key thing is likely that you want to start Karma after Steal has finished loading. To do that you can use:

  if(window.__karma__) {

How/where you add this bit of code is unfortunately beyond my knowledge of Karma. I hope this helps though.


@blink1073 I set up a simple project with Karma & StealJS. Like @matthewp mentioned, it’s a lot like setting up Karma with RequireJS. The biggest difference is that you’ll need to manually set Karma to run asynchronously. This is normally done by the karma-requirejs adapter.

I used karma init to create a base karma.conf.js file with most of the default values. Then I added file patterns for all of the files that would be loaded by Steal. These are set as included: false so that Karma will not create script tags for them. I then added Steal and karma.bootstrap.js. karma.bootstrap.js will run the code @matthewp gave above, you can call it whatever you want. It’s discussed more below.

Here is what the karma configuration looks like in my project:

module.exports = function(config) {
    basePath: '',
    frameworks: ['qunit'],
    files: [
      { pattern: 'src/**/*.js', included: false },
      { pattern: 'src/**/*.stache', included: false },
      { pattern: 'src/**/*.less', included: false },
      { pattern: 'node_modules/steal/**/*.js', included: false },
      { pattern: 'node_modules/can/**/*.js', included: false },
      { pattern: 'node_modules/funcunit/**/*.js', included: false },
      { pattern: 'node_modules/can-fixture/**/*.js', included: false },
      { pattern: 'node_modules/done-css/**/*.js', included: false },
      { pattern: 'node_modules/can-connect/**/*.js', included: false },
      { pattern: 'node_modules/jquery/**/*.js', included: false },
      { pattern: 'node_modules/**/package.json', included: false },
      { pattern: 'package.json', included: false },
    exclude: [ ],
    preprocessors: { },
    reporters: ['progress'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: false,
    browsers: ['Firefox'],
    singleRun: true,
    concurrency: Infinity

The karma.bootstrap.js file just needs to overwrite the window.__karma__.loaded function. This function normally starts Karma, but we need it to configure Steal and then start Karma once Steal is done. Here’s what karma.bootstrap.js looks like in my project:

window.__karma__.loaded = function() {
  System.main = 'src/test/';

    if(window.__karma__) {

The only other thing I saw was that using steal-qunit would cause a warning about QUnit.start() being called multiple times, so I changed my project to use regular QUnit instead.


Thanks @matthewp and @phillipskevin, the bootstrap override worked nicely.


Further to the posts above, if you want to load all your tests dynamically, there are a couple of changes needed. First the karma.bootstrap.js becomes:

window.__karma__.loaded = function() {
    System.main = 'tests/include-all-tests';

include-all-tests.js is:

var tests = [];
for (var file in window.__karma__.files) {
    if (window.__karma__.files.hasOwnProperty(file)) {
        if (/base\/tests\/.*-test\.js$/.test(file)) {

tests[tests.length] = function() {
    if(window.__karma__) {

steal.apply(null, tests);

Be sure to make the appropriate changes to the path to your tests and the Spec qualifier (I use -test instead of Spec). Note, you need to strip off the ‘/base/’ from the beginning of each test file name.


@coliphant @phillipskevin I am getting a following error

“Uncaught ReferenceError: System is not defined” at karma.bootstrap.js:2

The above error comes up at line “System.main = ‘tests/include-all-tests’;”

Any idea what could be wrong? Please let me know once you get a chance. Thanks.