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Cucumber.js Build Status

Cucumber, the popular Behaviour-Driven Development tool, brought to your JavaScript stack.

It runs on both Node.js and modern web browsers.

Try it now:!

Development status

Cucumber.js is still a work in progress. Here is its current status.

Cucumber Technology Compatibility Kit

Feature Status
Core (scenarios, steps, mappings) Done
Background Done1
Calling steps from step defs To do
Comments Done
Command-line interface Done1, 2
Command-line options To do2
Data tables Done
Doc Strings Done
Failing steps Done
Hooks Done
I18n To do
JSON formatter To do
Pretty formatter To do2
Scenario outlines and examples To do
Stats collector To do
Step argument transforms To do
Tags Done
Undefined steps Done
Wire protocol To do
World Done
  1. Not certified by Cucumber TCK yet.
  2. Considered for removal from Cucumber TCK.
  3. Simple Around, Before and After hooks are available.

Cucumber.js-specific features

Feature Status
Background Done1
CoffeeScript support Done
Command-line interface Done
  1. Will be certified by Cucumber TCK.


Cucumber.js is tested on:

  • Node.js 0.4, 0.6 (see CI builds) and supposedly 0.5.
  • Google Chrome
  • Firefox
  • Safari
  • Opera

There are plans to have CI builds on browsers too.



Cucumber.js is available as an npm module.

Install globally with:

$ npm install -g cucumber


You may also define cucumber.js as a development dependency of your application by including it in a package.json file.

// package.json

{ "devDependencies" : {
    "cucumber": "latest"

Then install with npm install --dev


Features are written with the Gherkin syntax

# features/myFeature.feature

Feature: Example feature
  As a user of cucumber.js
  I want to have documentation on cucumber
  So that I can concentrate on building awesome applications

  Scenario: Reading documentation
    Given I am on the Cucumber.js Github repository
    When I go to the README file
    Then I should see "Usage" as the page title

Support Files

Support files let you setup the environment in which steps will be run, and define step definitions. Both JavaScript (.js) and CoffeeScript (.coffee) source files are supported.


World is a constructor function with utility properties, destined to be used in step definitions:

// features/support/world.js

var zombie = require('zombie');
var World = function World(callback) {
  this.browser = new zombie.Browser(); // this.browser will be available in step definitions

  this.visit = function(url, callback) {
    this.browser.visit(url, callback);

  callback(); // tell Cucumber we're finished and to use 'this' as the world instance
exports.World = World;

It is possible to tell Cucumber to use another object instance than the constructor:

// features/support/world.js

var zombie = require('zombie');
var WorldConstructor = function WorldConstructor(callback) {
  this.browser = new zombie.Browser(); // this.browser will be available in step definitions

  var world = {
    visit: function(url, callback) {
      this.browser.visit(url, callback);

  callback(world); // tell Cucumber we're finished and to use our world object instead of 'this'
exports.World = WorldConstructor;

Step Definitions

Step definitions are the glue between features written in Gherkin and the actual SUT (system under test). They are written in JavaScript.

All step definitions will run with this set to what is known as the World in Cucumber. It's an object exposing useful methods, helpers and variables to your step definitions. A new instance of World is created before each scenario.

Step definitions are contained within one or more wrapper functions.

Those wrappers are run before executing the feature suite. this is an object holding important properties like the Given(), When() and Then() functions. Another notable property is World; it contains a default World constructor that can be either extended or replaced.

Step definitions are run when steps match their name. this is an instance of World.

// features/step_definitions/myStepDefinitions.js

var myStepDefinitionsWrapper = function () {
  this.World = require("../support/world.js").World; // overwrite default World constructor

  this.Given(/^I am on the Cucumber.js Github repository$/, function(callback) {
    // Express the regexp above with the code you wish you had.
    // `this` is set to a new this.World instance.
    // i.e. you may use this.browser to execute the step:

    this.visit('', callback);

    // The callback is passed to visit() so that when the job's finished, the next step can
    // be executed by Cucumber.

  this.When(/^I go to the README file$/, function(callback) {
    // Express the regexp above with the code you wish you had. Call callback() at the end
    // of the step, or callback.pending() if the step is not yet implemented:


  this.Then(/^I should see "(.*)" as the page title$/, function(title, callback) {
    // matching groups are passed as parameters to the step definition

    if (!this.isOnPageWithTitle(title))
      // You can make steps fail by calling the `fail()` function on the callback: Error("Expected to be on page with title " + title));

module.exports = myStepDefinitionsWrapper;

It is also possible to use simple strings instead of regexps as step definition patterns:

this.Then('I should see "$title" as the page title', function(title, callback) {
  // the above string is converted to the following Regexp by Cucumber:
  // /^I should see "([^"]*)" as the page title$/

  if (!this.isOnPageWithTitle(title))
    // You can make steps fail by calling the `fail()` function on the callback: Error("Expected to be on page with title " + title));

'I have $count "$string"' would translate to /^I have (.*) "([^"]*)")$/.


Hooks can be used to prepare and clean the environment before and after each scenario is executed.

Before hooks

To run something before every scenario, use before hooks:

// features/support/hooks.js (this path is just a suggestion)

var myHooks = function () {
  this.Before(function(callback) {
    // Just like inside step definitions, "this" is set to a World instance.
    // It's actually the same instance the current scenario step definitions
    // will receive.

    // Let's say we have a bunch of "maintenance" methods available on our World
    // instance, we can fire some to prepare the application for the next
    // scenario:


    // Don't forget to tell Cucumber when you're done:

module.exports = myHooks;
After hooks

The before hook counterpart is the after hook. It's similar in shape but is executed, well, after every scenario:

// features/support/after_hooks.js

var myAfterHooks = function () {
  this.After(function(callback) {
    // Again, "this" is set to the World instance the scenario just finished
    // playing with.

    // We can then do some cleansing:


    // Release control:

module.exports = myAfterHooks;
Around hooks

It's also possible to combine both before and around hooks in one single definition with the help of around hooks:

// features/support/advanced_hooks.js

myAroundHooks = function() {
  this.Around(function(runScenario) {
    // "this" is - as always - an instance of World promised to the scenario.

    // First do the "before scenario" tasks:


    // When the "before" duty is finished, tell Cucumber to execute the scenario
    // and pass a function to be called when the scenario is finished:

    runScenario(function(callback) {
      // Now, we can do our "after scenario" stuff:


      // Tell Cucumber we're done:

module.exports = myAroundHooks;
Tagged hooks

Hooks can be conditionally elected for execution based on the tags of the scenario.

// features/support/hooks.js (this path is just a suggestion)

var myHooks = function () {
  this.Before("@foo", "@bar,@baz", function(callback) {
    // This hook will be executed before scenarios tagged with @foo and either
    // @bar or @baz.

    // ...


module.exports = myHooks;

Run cucumber

Cucumber.js includes a binary file to execute the features.

If you installed cucumber.js with npm install --dev, you may run cucumber with:

  @NODE_ENV=test ./node_modules/.bin/cucumber.js

You may specify the features to run:

  @NODE_ENV=test ./node_modules/.bin/cucumber.js features/myFeature.feature

And require specific step definitions with the --require option:

  @NODE_ENV=test ./node_modules/.bin/cucumber.js features/myFeature.feature \
    --require features/step_definitions/myStepDefinitions.js


A few example apps are available for you to browse:

Setup for using in Node.js and running tests

Install the required dependencies:

$ npm link


$ node example/server.js

Then go to localhost:9797.

Run tests


$ node_modules/.bin/jasmine-node spec

Features & documentation

There is a common set of features shared by all cucumber implementations. It's called the Technology Compatibility Kit or TCK. Find more on the Cucumber TCK repository.

The official way of running them is through Cucumber-ruby and Aruba. Ruby and Bundler are required for this to work.

$ git submodule update --init
$ bundle
$ rm -rf doc; ARUBA_REPORT_DIR=doc cucumber features/cucumber-tck -r features

Note: you need the bcat and rdiscount gems in order to use the ARUBA_REPORT_DIR environment variable. Install it with gem install bcat rdiscount.

You can then open the generated documentation:

$ open doc/features/cucumber-tck/*.html # might open a lot of files ;)

In addition to that, Cucumber.js is able to run the features for itself too:

$ ./bin/cucumber.js features/cucumber-tck -r features

There are a few other Cucumber.js-dependent features. Execute everything:

$ ./bin/cucumber.js


Alternatively, you can run everything with the help of Rake:

$ git submodule update --init
$ bundle
$ rake

Debug messages

You can display debug messages by setting the DEBUG_LEVEL environment variable. It goes from 1 to 5. 5 will display everything, 1 will only print out the critical things.

$ DEBUG_LEVEL=5 ./bin/cucumber.js

It even works with Aruba:

$ rm -rf doc; DEBUG_LEVEL=5 ARUBA_REPORT_DIR=doc cucumber features/cucumber-tck -r features
$ open doc/features/cucumber-tck/*.html # you'll see debug messages in Aruba-generated docs

Help & support

Release checklist

  • Update development status in, if relevant
  • Update
  • Bump version in lib/cucumber.js
  • Bump version in package.json
  • Add new contributors to package.json, if any
  • Commit those changes as "Release 0.1.2" (where 0.1.2 is the actual version, of course)
  • Tag commit as "v0.1.2" with short description of main changes
  • Push to main repo on Github
  • Wait for build to go green
  • Publish to NPM
  • Deploy to
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