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Run TAP unit tests in 1789+ browsers. Airtap is a command-line interface to unit test your JavaScript in browsers, using a TAP-producing harness like tape. Start testing locally and seamlessly move to browsers in the cloud for full coverage. Airtap runs browsers concurrently and lets you iterate quickly during development. Don't just claim your JavaScript supports "all browsers", prove it with tests!

npm Node version Test Standard Common Changelog

Table of Contents

Click to expand


With npm do:

npm install airtap --save-dev

If you are upgrading or migrating from zuul: please see the upgrade guide.

Getting Started

You'll need an entry point for your tests like test.js. For a complete example see airtap-demo. If you already have an entry point, go ahead and run it with:

airtap test.js

Out of the box, this will launch the default browser on your system. To keep the browser open and automatically reload when you make changes to your test files, run:

airtap --live test.js

Adding Browsers

In order to run other (and more than one) browsers, create a .airtap.yml file in your working directory, containing at least one provider and at least one browser. For example:

  - airtap-system

  - name: chrome
  - name: ff

Providers discover browsers on a particular platform or remote service. In the above example, airtap-system finds browsers installed on your machine which Airtap then matches against the browsers you specified.

You can include multiple providers and let Airtap find the best matching browser(s):

  - airtap-playwright
  - airtap-system

  - name: ff
    version: 78

You can also match browsers by provider:

Click to expand
  - name: ff
    provider: airtap-system

Airtap, providers and browsers are tied together by manifests. They define the name and other metadata of browsers. You can see these manifests by running airtap -l or -la which is short for --list-browsers --all. For example:

Click to expand
$ airtap -la
- name: electron
  title: Electron 9.0.5
  version: 9.0.5
    headless: true
  provider: airtap-electron

Airtap can match browsers on any manifest property, with the exception of options which exists to customize the browser behavior. Options are specific to a provider. For example, the airtap-playwright provider supports disabling headless mode and setting custom command-line arguments:

  - name: chromium
      headless: false
        args: [--lang=en-US]

For more information on the browsers field, see Configuration.

Available Providers

Providers must be installed separately.

Package Description
airtap-system Locally installed browsers on Linux, Mac & Windows
airtap-playwright Playwright (headless Chromium, FF and WebKit)
airtap-sauce Remote browsers in Sauce Labs
airtap-electron Electron
airtap-default Default browser
airtap-manual Manually open a URL in a browser of choice

Cloud Testing With Sauce Labs

The airtap-sauce provider runs browsers on Sauce Labs. Sauce Labs offers quite a few browsers, with a wide range of versions and platforms.

Open source projects can use the free for open source version of Sauce Labs.

1. Set Credentials

Airtap needs to know your Sauce Labs credentials. You don't want to commit these sensitive credentials to your git repository. Instead set them via the environment as SAUCE_USERNAME and SAUCE_ACCESS_KEY.

2. Select Browsers

Add the airtap-sauce provider and wanted browsers to .airtap.yml:

  - airtap-sauce

  - name: chrome
  - name: ios_saf
  - name: ie

3. Set Hostname

Airtap runs a server to serve JavaScript test files to browsers. The airtap-sauce provider establishes a tunnel to your local machine so that Sauce Labs can find that server. For this to work, some browsers need a custom loopback hostname, because they don't route localhost through the tunnel. Add the following to your hosts file: airtap.local

You are now ready to run your tests in the cloud with airtap test.js.

Continuous Integration

After making sure your tests pass when initiated from your local machine, you can setup continuous integration to run your tests whenever changes are committed. Any CI service that supports Node.js will work.

Sauce Test Status

Travis CI

1. Setup Travis

Take a look at the Travis getting started guide for Node.js. At minimum we need to create a .travis.yml file containing:

language: node_js
  - 12
    - airtap.local

2. Add Test Script

Add the following to your package.json:

  "scripts": {
    "test": "airtap test.js"

3. Enable Code Coverage

Optionally enable code coverage with the --coverage flag. This will collect code coverage per browser into the .nyc-output/ folder in Istanbul 1.0 format. Afterwards you can generate reports with nyc report, which takes care of merging code coverage from multiple browsers.

A typical setup for Travis looks like:

  "scripts": {
    "test": "airtap --coverage test.js"

You can choose to post the results to coveralls (or similar) by adding a step to .travis.yml:

after_success: npm run coverage
  "scripts": {
    "test": "airtap --coverage test.js",
    "coverage": "nyc report --reporter=text-lcov | coveralls"

4. Set Credentials

Skip this step if you're not using the airtap-sauce provider. Same as when initiating tests locally, we need to get Sauce Labs credentials to Travis. Luckily Travis has a feature called secure environment variables. You'll need to set 2 of those: SAUCE_USERNAME and SAUCE_ACCESS_KEY.

GitHub Actions

Should work in theory :)


Usage: airtap [options] <files>. Supports multiple files. They can be paths relative to the working directory or glob patterns (e.g. airtap test/*.js). Options:

-v --version          Print version and exit
-l --list-browsers    List (effective or --all) browsers
-a --all              Test or list all available browsers
   --coverage         Enable code coverage analysis
   --live             Keep browsers open to allow repeated test runs
-c --concurrency <n>  Number of browsers to test concurrently, default 5
-r --retries <n>      Number of retries when running a browser, default 6
-t --timeout <n>      How long to wait for test results, default 5m. Can
                      be a number in milliseconds or a string with unit.
-p --preset <preset>  Select a configuration preset
-s --server <script>  Path to script that runs a support server
   --loopback <host>  Custom hostname that equals or resolves to
   --verbose          Enable airtap debug output
   --silly            Enable all debug output
-h --help             Print help and exit.
Examples (click to expand)

List all available browsers:

airtap -la

Test browsers specified in .airtap.yml:

airtap test.js

Test all available browsers (careful):

airtap -a test.js

Test multiple files:

airtap "test/*.js"


Airtap consumes a YAML config file at .airtap.yml in the working directory. The following fields are available.

providers (array)

browsers (array)

List of browsers to test in the cloud. Each entry should contain a name property. Additional properties like version and platform may be specified depending on the provider.

The version property defaults to latest and can be a specific version number, the keyword latest, the keyword oldest, or (for Firefox and Chrome) one of the keywords beta or dev.

  - name: chrome
  - name: firefox
    version: beta

Specific version of a browser on a specific platform

Only supported by the airtap-sauce provider at the time of writing, as other providers do not run browsers on a particular platform.

  - name: chrome
    version: 28
    platform: Windows XP

Range of versions of a browser

  - name: firefox
    version: 14..latest
  - name: ie
    version: 9..11

Range of versions with negative start index.

This example would test the latest three stable versions of Firefox (latest - 2, latest - 1, latest).

  - name: firefox
    version: -2..latest

Disjoint versions

  - name: firefox
    version: [19, 20]

Disjoint with ranges

  - name: firefox
    version: [19, 20, 23..latest]
  - name: chrome
    version: [-1..latest, beta]

Float version numbers

  - name: ios_saf
    version: '8.0..latest'

Float version numbers should be quoted.

browserify (array)

You can set any of the items in the following list, and they'll be passed to browserify.

  • plugin
  • external
  • ignore
  • exclude
  • transform
  • add
  • require

They can be repeated and accept options.

  - require: ./some-file.js
    expose: intimidate
  - transform: brfs
  - transform: jadeify

You can also customize what's passed to browserify(options).

  - options:
      node: true

IE < 11 support

To support IE < 11, an older version of the buffer polyfill is required. Use the following configuration and run npm install buffer@4:

# Use buffer@4 to support IE < 11
  - require: 'buffer/'
    expose: 'buffer'

server (string or object)

This field can point to an optional shell command or JavaScript file to run as a support server. It will be started before all tests and stopped afterwards. This allows testing websockets and other network requests. Your command will be run with the AIRTAP_SUPPORT_PORT environment variable set to a port number you must use. If your server does not listen on this port it will be unreachable (on browser providers that use a tunnel).

server: ./test/support/server.js

We recommend writing simple support servers using http or express. For shell commands you can use $AIRTAP_SUPPORT_PORT in the arguments, which will be substituted:

server: "python -m SimpleHTTPServer $AIRTAP_SUPPORT_PORT"

Firefox Profile

The airtap-sauce provider supports running Firefox instances with custom user profiles. This allows you to configure anything you can change in about:config programmatically for a test run. You can set these options with a section under any Firefox browser entry:

  - name: firefox
        webgl.force-enabled: true

Who Uses Airtap?

Lots of folks! Collectively, packages that depend on Airtap get 100's of millions of downloads per month!


Airtap is an OPEN Open Source Project. This means that:

Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.

See the contribution guide for more details.


MIT © Roman Shtylman, Zuul contributors and Airtap contributors.

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