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Karma Plus Sauce

Run your unit tests on Sauce Labs' browser cloud!


Install karma-sauce-launcher as a devDependency in your package.json:

npm install karma-sauce-launcher --save-dev


This launcher is typically used in CI to run your unit tests across many browsers and platforms on Sauce Labs. However, you can also use it locally to debug tests in browsers not available on your machine. It is expected that you are already familiar with Karma when configuring this launcher, so if you are new to Karma, head over to the Karma website.

The Sauce Labs platform configurator can help to find the correct configuration for your desired test platform.

Adding karma-sauce-launcher to an existing Karma config

To configure this launcher, you need to add two properties to your top-level Karma config, sauceLabs and customLaunchers, set the browsers array to use Sauce Labs browsers, and add the sauceLabs reporter.

The sauceLabs object defines global properties for each browser/platform while the customLaunchers object configures individual browsers. The sauceLabs reporter allows your tests results to be properly displayed on https://saucelabs.com. Here is a sample Karma config to get the launcher running:

module.exports = function(config) {
  // Example set of browsers to run on Sauce Labs
  // Check out https://saucelabs.com/platforms for all browser/platform combos
  var customLaunchers = {
    // Old JSONWP way of setting the capabilities
    sl_chrome: {
      base: 'SauceLabs',
      browserName: 'chrome',
      platform: 'Windows 10',
    sl_firefox: {
      base: 'SauceLabs',
      browserName: 'firefox',
      version: 'latest'
    sl_ie_11: {
      base: 'SauceLabs',
      browserName: 'internet explorer',
      platform: 'Windows 8.1',
    // Mobile settings
    // 1. Go to https://wiki.saucelabs.com/display/DOCS/Platform+Configurator#/
    // 2. Select Appium iOS,Android
    // 3. Configure your device
    //    Don't forget to provide the `appiumVersion`
    sl_ios_safari: {
      base: 'SauceLabs',
      deviceName: 'iPhone 11 Simulator',
      platformVersion: '13.4',
      platformName: 'iOS',
      browserName: 'Safari',
      appiumVersion: '1.17.1',
      deviceOrientation: 'portrait'
    // !!!!IMPORTANT!!!!
    // If you want to use an Android emulator then you can't use localhost.
    // Because an Android emulator is a VM it will go to it's own localhost
    // and the test will fail. Make change the `hostname` to your
    // local ip
    sl_android: {
      base: 'SauceLabs',
      deviceName: 'Android GoogleAPI Emulator',
      platform: 'Android',
      version: '11.0',
      browserName: 'chrome',
      appiumVersion: '1.18.1',
      deviceOrientation: 'portrait'
    // For W3C way of setting the capabilities check
    // https://wiki.saucelabs.com/display/DOCS/Platform+Configurator#/
    // And select WebDriver (W3C) Selenium 3/4, Webdriver.io
    sl_chromeW3C: {
      base: 'SauceLabs',
      browserName: 'chrome',
      browserVersion: 'latest',
        tags: ['w3c-chrome']


    // The rest of your karma config is here
    // ...
    sauceLabs: {
        testName: 'Web App Unit Tests'
    customLaunchers: customLaunchers,
    browsers: Object.keys(customLaunchers),
    reporters: ['dots', 'saucelabs'],
    singleRun: true

Note: this config assumes that process.env.SAUCE_USERNAME and process.env.SAUCE_ACCESS_KEY are set.

Example karma-sauce-launcher configs

For example configs using this launcher (using Travis CI), check out this repo's karma file, or AngularJS' Karma config.

Example results in Sauce Labs

Version 4.2.0 and lower of this module will give you the following result in Sauce Labs, no matter how many tests you execute.

Sauce Logs

As of version 4.3.0 the logs are replaced with the test names and results of the individual tests that have been executed on Sauce Labs, including the execution url in the logs.

Successful run Sauce Successful Logs

Unsuccessful run Sauce Successful Logs

Execution url Sauce Successful Logs

sauceLabs config properties shared across all browsers


Type: String Default: process.env.SAUCE_USERNAME

Your Sauce Labs username (if you don't have an account, you can sign up here).


Type: String Default: process.env.SAUCE_ACCESS_KEY

Your Sauce Labs access key which you will see on your account page.


Type: String

Detect datacenter to run tests in. Can be either eu or us.


Type: Boolean

If set to true tests are being run on Sauce Labs headless platform on us-east-1. This option will be ignored if region is set.


Type: String

Proxy for connecting to Sauce REST API, which is used to communicate job updates of pass/fail.


Type: Boolean Default: true

If true, Sauce Connect will be started automatically. Set this to false if you are launching tests locally but want to start Sauce Connect via a binary manually in the background to improve test speed.


Type: Object Default:

  username: 'yourUsername',
  accessKey: 'yourAccessKey',
  tunnelIdentifier: 'autoGeneratedTunnelID'

Options to send to Sauce Connect.

Check here for all available options. All parameters have to be applied camel cased instead of with hyphens.


Type: String Default: One of the following environment variables: process.env.BUILD_NUMBER process.env.BUILD_TAG process.env.CI_BUILD_NUMBER process.env.CI_BUILD_TAG process.env.TRAVIS_BUILD_NUMBER process.env.CIRCLE_BUILD_NUM process.env.DRONE_BUILD_NUMBER

ID of the build currently running. This should be set by your CI.


Type: String Default: 'Karma test'

Name of the unit test group you are running.


Type: String

Sauce Connect can proxy multiple sessions, this is an id of a session.


Type: Array of Strings

Tags to use for filtering jobs in your Sauce Labs account.


Type: Boolean Default: false

Set to true if you want to record a video of your Karma session.


Type: Boolean Default: true

Set to false if you don't want to record screenshots.


Type: String Default: null

Control who can view job details. Available visibility levels are documented on the SauceLabs website.


Type: Object Default: {}

Send arbitrary data alongside your tests. See the SauceLabs documentation for more details.

customLaunchers config properties

The customLaunchers object has browser names as keys and configs as values. Documented below are the different properties which you can configure for each browser/platform combo.

Note: You can learn about the available browser/platform combos on the Sauce Labs platforms page, platforms configurator page and REST API page.


Type: String Required: true

This defines the base configuration for the launcher. In this case it should always be SauceLabs so that browsers can use the base Sauce Labs config defined at the root sauceLabs property.


Type: String Required: true

Name of the browser.


Type: String Default: Latest browser version for all browsers except Chrome

Version of the browser to use.


Type: String Default: 'Linux' for Firefox/Chrome, 'Windows 7' for IE/Safari

Name of platform to run browser on.


Specific Sauce Labs capability options.

Behind the scenes

This launcher uses Sauce Connect in the background. If you are interested in security or want to see the system requirements, head over to the documentation.

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