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This library should be considered deprecated in favor of using Mocha, which offers a similar BDD-style API.

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3.1.0 • Public • Published


BDD-style testing for QUnit.

NOTE: This library should be considered deprecated in favor of using Mocha, which offers a similar BDD API. You're welcome to use it, but please do not expect a response to issues or pull requests.

describe('keys', function() {
  describe('.camelize', function() {
    it('camelizes top-level keys', function() {
      expect(camelize({ ohai_there: 'friend' })).to.eql({ ohaiThere: 'friend' });
    it('camelizes nested keys', function() {
      expect(camelize({ foo_bar: { bar_baz: 'baz' } }))
        .to.eql({ fooBar: { barBaz: 'baz' } });
    it('camelizes array objects', function() {
      expect(camelize([{ foo_bar: { bar_baz: 'baz' } }, { ohai_there: 'friend' }]))
        .to.eql([{ fooBar: { barBaz: 'baz' } }, { ohaiThere: 'friend' }]);


# Install via Yarn. 
$ yarn add --dev qunit-bdd
# Install via NPM. 
$ npm install [--save-dev] qunit-bdd
# Install from Git. 
$ git clone
$ cp qunit-bdd/lib/qunit-bdd.js my-project/vendor/qunit-bdd.js


QUnit must be installed alongside this package.

qunit-bdd Supported QUnit Versions
v1.x v1.x
v2.x v2.0 - v2.5.1
v3.x v2.6+


qunit-bdd has describe and context, just like Mocha and Jasmine. It also provides an assertion syntax similar to expect.js.

describe('Math', function() {
  describe('#pow', function() {
    it('raises the first argument to the power of the second argument', function() {
      expect(Math.pow(0, 6)).to.equal(0, '0**x == 0');
      expect(Math.pow(1, 99)).to.equal(1, '1**x == 1');
      expect(Math.pow(99, 0)).to.equal(1, 'x**0 == 1');
      expect(Math.pow(2, 3)).to.equal(8, 'positive exponent works');
      expect(Math.pow(4, -1)).to.equal(2, 'negative exponent works');

qunit-bdd also has before and after to run blocks of code before an after each test run within a context:

// This example uses sinon.js, not included with qunit-bdd.
describe('Profile Page', function() {
  before(function() {
    this.alertStub = sinon.stub(window, 'alert');
  it('alerts on errors', function() {
    expect(this.alertStub.calledWith('UH OH!'));
  after(function() {

Additionally, qunit-bdd ships with support for RSpec-style per-context let values, called lazy values in qunit-bdd. This is very useful when you want to declare how to set up a complex object in a top-level context, overriding parts of that setup in nested contexts:

describe('Person', function() {
  lazy('person', function() {
    return new Person({
      firstName: this.firstName,
      lastName: this.lastName,
      dob: this.dob,
      address: this.address
  lazy('address', function() {
    return {
      street1: this.street1,
      street2: this.street2,
      state: this.state,
      postal: this.postal
  // Defaults for dependent values could be put here (e.g. firstName, street1, etc).
  describe('#canVote', function() {
    context('when the person is not yet 18', function() {
      lazy('dob', function(){ return new Date(); });
      it('is false', function() {
    context('when the person is over 18', function() {
      lazy('dob', function(){ return new Date(0); });
      it('is true', function() {

The benefit to this approach over setting up your test objects in before is that you can override parts of the built objects declaratively in nested contexts, something you might have used a bunch of helper functions to do with QUnit's default module/test functions.

You can also use helper to define helper functions that have access to everything defined on the test context. This is useful for reusing a piece of code between tests that have different setups. Example:

describe('APIRequest', function() {
  before(function() {
    this.url = "";
    this.apiController = new ApiController();
    this.moreTestState = {};
  helper('fireApiRequest', function() {
    // full access to everything on current context.
    this.apiController.ajax(this.url, this.moreTestState);
  it('works', function() {
    // ... test-specific setup
  it('works in another context', function() {
    // ... test-specific setup


qunit-bdd supports async functions as before, after, or it callbacks. You may also return Promise objects from before, after, and it blocks as a means of writing async tests. We rely on QUnit's own mechanism for this functionality, which means we require at leastd QUnit v1.16. Here's a basic example:

describe('delay', function() {
  it('returns a promise that resolves after Nms', async function() {
    await delay(10);
    ok(true, 'promise resolved!');

You can write this using explicit Promise syntax if you prefer:

describe('delay', function() {
  it('returns a promise that resolves after Nms', function() {
    return delay(10).then(() => {
      ok(true, 'promise resolved!');


It's still QUnit, so you can write some tests using the module/test style, complete with the usual ok/equal/deepEqual assertions, if you find it more appropriate sometimes. Also, you can export as much or as little of qunit-bdd to the global scope as you like:

// Turn off `lazy` and `context` exports.
// Make sure to set this before loading qunit-bdd.js.
    lazy: false,  // don't use lazy
    expect: false // use the regular QUnit assertions (or another set altogether)


By default your tests will run in the order in which they are defined. This is usually desirable for interactive development and debugging. But for continuous integration you may want to run your tests in a random order to reveal any hidden dependencies between your tests that may be causing them not to work as expected. To turn this on, set QUNIT_BDD_OPTIONS.randomize to true. Doing so will first shuffle your describes, then shuffle the its within.

If you want to use a particular randomizer, pass a function that takes an array and returns a shuffled array instead of true. For example, here's how to configure qunit-bdd to use chance.js with a random (but repeatable, for reproducing failures locally) seed:

var seed = Math.floor(Math.random() * 1000);
console.log('Random test order seed:', seed);
var chance = new Chance(seed);
  randomize: function(array) {
    return chance.shuffle(array);

Skipping Tests

You can also configure which tests are run, which can aid in debugging. To skip a particular test (or context), use it.skip() instead of it() (or describe.skip() instead of describe()). To run only a particular test (or context), use it.only() instead of it (or describe.only() instead of describe()).

Expectations / Assertions

You can configure the built-in assertion expect() function to add your own custom assertions or override the built-in ones:

  // expect(2);
  even: function() {
    QUnit.ok(!(this._actual % 2), 'expected ' + this._actual + ' to be even');

Note that the expect() function can still be used as you would while writing QUnit tests the normal way, i.e. as expect(4) to set the number of expected assertions.


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Come chat on our Google Group page or use the qunit-bdd tag on Stack Overflow.



First, install the development dependencies:

$ yarn

Then, try running the tests:

$ yarn test


As you make changes you may find it useful to have everything automatically compiled and ready to test interactively in the browser. You can do that using the develop script:

$ yarn run develop

Then go to http://localhost:8000/test in your browser (run with PORT={port} to override the default port).

Pull Requests

Contributions via pull requests are very welcome! Follow the steps in Developing above, then add your feature or bugfix with tests to cover it, push to a branch, and open a pull request.

Any contributors to the master qunit-bdd repository must sign the Individual Contributor License Agreement (CLA). It's a short form that covers our bases and makes sure you're eligible to contribute.

When you have a change you'd like to see in the master repository, send a pull request. Before we merge your request, we'll make sure you're in the list of people who have signed a CLA.


QUnit is a well-tested testing framework used by projects such as jQuery and Ember. It works very well for unit-style testing with fairly simple inputs and outputs. It is less well suited to acceptance or integration testing, where you often want to test slight variations of the same thing. The nested context of the BDD style translate well to this sort of need.

You might be wondering, "Why not just use Pavlov?" That is a reasonable question. Pavlov has been around for some time and has reached the point, much like QUnit itself, where not much changes. Both are stable and reliable. Unfortunately, Pavlov has a number of assumptions that did not work well with how we test applications at Square. We wanted the ability to use multiple before and after blocks per describe (for shared examples). We wanted async to be a first-class citizen, not something to be avoided. Pavlov runs before blocks synchronously from the outermost to the innermost describe. We needed to be able to pause until the before in an outer describe finished before running the before in the next inner describe. Finally, we wanted an equivalent to RSpec's let to give us a more declarative style for our objects under test, complete with easy overrides in nested contexts. This is lazy in qunit-bdd.



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