Grunt task to run Mocha tests against a Selenium grid

npm install grunt-mocha-webdriver
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A Grunt task that runs Mocha-based functional tests against a Webdriver-enabled source: specifically, PhantomJS for local testing and Sauce Labs for comprehensive cross-browser testing. This plugin is a combination of mocha-cloud and grunt-saucelabs. The former library doesn't have Grunt integration built in, and is designed for running tests inside the browser; the latter library can launch a grid of browsers on Sauce Labs, but doesn't support Mocha.

Getting Started

This plugin requires Grunt >=0.4.0; connecting to Sauce Labs requires java.

Install the plugin with:

npm install grunt-mocha-webdriver --save-dev

Then add this line to your project's Gruntfile:


Using grunt-mocha-webdriver with Phantomjs

In version 0.9.4 and later, phantom is included via its NPM module. In order to run tests against phantom, simply add the usePhantom flag to the options hash. The plugin defaults to hitting port 4444, but you can specify your own port via the phantomPort option.

Using grunt-mocha-webdriver with your own Selenium server

In version 0.9.15 and later, You can run your tests against your own Selenium server instance. To do so, use hostname and port options. Don't forget to remove username and key. Note that the Selenium server should be started and ready before starting the tests.


Run this task with the mochaWebdriver grunt command. For this plugin, the Grunt src property will specify which test files should be run with Mocha in the mochaWebdriver multitask. These tests should be structured as normal Mocha tests, but should use this.browser to refer to a WebDriver browser which will be injected into the test's context. The browser can be driven with the API specified in WD.js. The default is to use the callback-enabled version of WD.js, but usePromises can be passed as true to switch to the Promise-enabled version.

As of version 0.2.3 of WD.js, wd provides the ability to add test methods to its default set of capabilities. grunt-mocha-webdriver exposes the wd instance in the same way that browser is exposed, so that you can easily add your own test methods to wd.

Also, Mocha options are exposed to tests. This is especially helpful if you want to reuse the defined Mocha timeout for your Webdriver tests. For example you can do this in your Webdriver based E2E tests:

this.browser.waitForElementByCss('.aClass', this.mochaOptions.timeout, cb);

Please look at this project's Gruntfile and tests to see all that in action.


The usual Mocha options are passed through this task to a new Mocha instance. Please note that while it's possible to specify the Mocha reporter for tests running on Phantom, there's only one reporter currently supported for tests against Sauce Labs. This restriction is in place to handle concurrent Sauce Labs testing sessions, which could pollute the log.

The following options can be supplied to the task:


Type: Boolean

Specifies whether the task should test against a PhantomJS instance instead of Sauce Labs. Defaults to false. If true, the tests will run against Phantom INSTEAD of running against Sauce Labs.


Type: Int (Default: 4444)

if testing against PhantomJS with the usePhantom flag, specify the port to test against.


Type: Object (Default: {})

if testing against PhantomJS with the usePhantom flag, specify the browser capabilities.


Type: Boolean

Specifies whether to use the Promise chain version of the WD.js API. Defaults to false (the callback version).


Type: Boolean

A passthrough to the Phantom CLI runner to ignore errors with SSL certs.


Type: Array

An array of paths for requiring before running Mocha tests. Useful for pre-requires that manipulate Mocha's global environment (e.g.g making Sinon globally available).


Type: String

The Sauce Labs username to use. Defaults to value of env var SAUCE_USERNAME.


Type: String

The Sauce Labs API key to use. Defaults to value of env var SAUCE_ACCESS_KEY.


Type: Boolean (Default: false)

If true, it will use saucelabs, with default hostname set to and port set to 4445 in order to send selenium commands through Sauce Connect tunnel (more info here).


Type: String

If specified, it will connect that selenium server instead of


Type: Int

Selenium server port. Should be used in conjonction with hostname.


Type: Number

A Unique identifier for the generated tunnel to Sauce Labs. Will be automatically generated if not specified. Useful for connected to existing Sauce tunnels.


Type: Int

The number of concurrent browser sessions to spin up on Sauce Labs. Defaults to 1.


Type: Array An array of option flags for Sauce Connect. See the list of available options here.


Type: String

The name of the test, as reported to Sauce Labs.


Type: [String]

An array of tags to associate with the test, as reported to Sauce Labs.


Type: [Object]

An array of objects specifying which browser options should be passed to Sauce Labs. Unless a test is run against Phantom (e.g. usePhantom is true), this option must be specified. Each browser hash should specify: browserName. For saucelabs tests, platform, and version are also required.


In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using grunt.

Release History


  • Initial release


  • Setup Travis for CI
  • Improve SauceLabs test failure handling
  • Test count was off by 1


  • Update docs
  • Add initial promise support (Phantom only)


  • Enable Promise support (Phantom and SauceLabs)


  • Run phantom from grunt-mocha-webdriver directly


  • Implement require option for pre-require hook


  • PhantomJS integration failed to report the correct status code when exiting Grunt after tests failed.


  • Prevent errors from causing Phantom to exit early
  • Better error messages via wd.js


  • ignoreSslErrors option added as a phantom CLI passthrough


  • Update wd.js to 0.2.0, and switch to the new promiseChain API


  • Fix promiseChain on Sauce


  • Fix #8, async failures were causing grunt exit


  • Bump to latst sauce-tunnel


  • Bump to 0.2.3 of WD, and expose the wd instance to tests


  • Bump to 1.15.1 of Mocha, and expose mocha options to tests


  • Add Selenium support (thanks to @saadtazi)


  • tunnelFlags options, courtesy of @saadtazi


  • Move to latest version of sauce tunnel / sauce connect
  • Added ability to specify phantomjs capabilities (@saadtazi)
  • Added secure commands for selenium (@saadtazi)


Copyright (c) 2013 Justin Reidy

Licensed under the MIT license.

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