RequireJS

To get Karma to run with Require.js we need two files:

  • karma.conf.js — which configures Karma
  • test-main.js — which configures Require.js for the tests

Let's imagine our app has a directory structure which looks something like this:

$ tree
.
|-- index.html
|-- karma.conf.js
|-- lib
|   |-- jquery.js
|   |-- require.js
|   `-- underscore.js
|-- src
|   |-- app.js
|   `-- main.js
`-- test
    |-- appSpec.js
    `-- test-main.js

3 directories, 9 files

Configure Karma

The first step is creating our karma.conf.js. We can do this from the command line:

$ karma init

This will give you a series of prompts for things such as paths to the source and test files as well as which browsers to capture.

In this example we'll use Jasmine, but other test frameworks work just as well.

Choose "yes" for Require.js.

For the question "Which files do you want to include with <script> tag?", we need to choose all files which are not loaded by Require.js. Usually, you'll only need to include your test-main.js file, which has the same role for your tests as main.js has for your app when using Require.js.

For the question "What is the location of your source and test files?", we choose all the files we want to load with Require.js. For this example we'll need:

  • lib/**/*.js — all external libraries
  • src/**/*.js — our source code
  • test/**/*Spec.js — all the tests

And then, when excluding files, type in src/main.js, as we don't want to actually start the application in our tests.

Now your karma.conf.js should include:

// list of files / patterns to load in the browser
module.exports = function(config) {
  config.set({
    frameworks: ['jasmine', 'requirejs'],

    files: [
      {pattern: 'lib/**/*.js', included: false},
      {pattern: 'src/**/*.js', included: false},
      {pattern: 'test/**/*Spec.js', included: false},

      'test/test-main.js'
    ],

    // list of files to exclude
    exclude: [
        'src/main.js'
    ]
  });
};

The files property contains every file you want to be available to the Karma runner. By default a script tag will be created for the files, unless you use the included: false option.

If you want a script tag to be added before requirejs (to load an amd compatible script before requirejs) then you must add the requirejs and adapter script to the files list and remove requirejs from the frameworks list. This allows you to control the order. For instance to load knockout.js before requirejs...

  config.set({
    frameworks: ['jasmine'],

    files: [
      'knockout.js',

      'node_modules/requirejs/require.js',
      'node_modules/karma-requirejs/lib/adapter.js',

      {pattern: 'lib/**/*.js', included: false},
      {pattern: 'src/**/*.js', included: false},
      {pattern: 'test/**/*Spec.js', included: false},

      'test/test-main.js'
    ],

Configuring Require.js

Just like any Require.js project, you need a main module to bootstrap your tests. We do this in test/test-main.js.

Karma /base Directory

Karma serves files under the /base directory. So, on the server requests to files will be served up under http://localhost:9876/base/*.

The Require.js config for baseUrl gives a starting context for modules that load with relative paths. When setting this value for the Karma server, it will need to start with /base. We want the baseUrl for our tests to be the same folder as the base url we have in src/main.js, so that relative requires in the source won’t need to change. So, as we want our base url to be at src/, we need to write /base/src.

Require Each Test File

With Karma we don't need to list all test files ourselves as we can easily find them from the files specified in test-main.js: Karma includes all the files in window.__karma__.files, so by filtering this array we find all our test files.

Now we can tell Require.js to load our tests, which must be done asynchronously as dependencies must be fetched before the tests are run. The test/test-main.js file ends up looking like this:

var TEST_REGEXP = /(spec|test)\.js$/i;
var allTestFiles = [];

// Get a list of all the test files to include
Object.keys(window.__karma__.files).forEach(function(file) {
  if (TEST_REGEXP.test(file)) {
    // Normalize paths to RequireJS module names.
    // If you require sub-dependencies of test files to be loaded as-is (requiring file extension)
    // then do not normalize the paths
    var normalizedTestModule = file.replace(/^\/base\/|\.js$/g, '');
    allTestFiles.push(normalizedTestModule);
  }
});

require.config({
  // Karma serves files under /base, which is the basePath from your config file
  baseUrl: '/base/src',

  // example of using a couple of path translations (paths), to allow us to refer to different library dependencies, without using relative paths
  paths: {
    'jquery': '../lib/jquery',
    'underscore': '../lib/underscore',
  },

  // example of using a shim, to load non AMD libraries (such as underscore)
  shim: {
    'underscore': {
      exports: '_'
    }
  },

  // dynamically load all test files
  deps: allTestFiles,

  // we have to kickoff jasmine, as it is asynchronous
  callback: window.__karma__.start
});

Using Require.js in tests

Tests can now be written as regular Require.js modules. We wrap everything in define, and inside we can use the regular test methods, such as describe and it. Example:

define(['app', 'jquery', 'underscore', './test-helper'], function(App, $, _, testHelper) {

    describe('just checking', function() {

        testHelper.setup();

        it('works for app', function() {
            var el = $('<div></div>');

            var app = new App(el);
            app.render();

            expect(el.text()).toEqual('require.js up and running');
        });

        it('works for underscore', function() {
            // just checking that _ works
            expect(_.size([1,2,3])).toEqual(3);
        });

    });

});

Running the tests

We can now run the tests from the command line:

$ karma start

If you didn't configure Karma to watch all the files and run tests automatically on any change, you can trigger the tests manually by typing:

$ karma run

Here is a running example of Karma with Require.js.