YUI's Easy Testing Interface: Run web app tests from the command line.
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Tired of testing? Yeti can help.

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Yeti automates tests written for various test frameworks. Yeti scales from your dev box (where it works by itself) to your CI system (where it launches browsers with Selenium) without changing your existing tests.


  • Automates your existing tests. Works with the framework you already have.
  • Automates tests without any additional software. Selenium not required!
  • Your tests can still run outside of Yeti by themselves.
  • Works with IE 6+, Android 4+, Firefox, Safari, Chrome, iOS 4+.
  • Server-side AJAX testing with echoecho.
  • JUnit XML output makes Yeti play nice with Jenkins.
  • Optional Selenium/WebDriver browser launching. Works great with Sauce Labs.

Test Frameworks

You can use any of these test frameworks with Yeti.

Install Yeti

npm install -g yeti

Yeti requires Node.js, which provides the npm command for installation. You can download Node.js source or pre-built installers from their website.

Using Yeti

Just run Yeti with the HTML files containing your tests.

$ yeti test/*.html
Creating a Hub at http://localhost:9000
Waiting for agents to connect at http://localhost:9000.
When ready, press Enter to begin testing.

Point your browsers at that URL, then come back and press Enter.

[Open some browsers...]

  Agent connected: Safari (6.0) / Mac OS
  Agent connected: Chrome (22.0.1221.0) / Mac OS

[Come back, press Enter]

✔ Testing started on Safari (6.0) / Mac OS, Chrome (22.0.1221.0) / Mac OS
✔ Agent completed: Safari (6.0) / Mac OS
✔ Agent completed: Chrome (22.0.1221.0) / Mac OS
504 tests passed! (9.1 seconds)

Yeti exits automatically when all tests complete. If test failures occur, Yeti will exit with a non-zero status code.

Please note before using Yeti on Windows, you must issue one of the following commands, depending on which command-line interface you are using:


set HOME = C:\Users\<username>

Windows PowerShell:

$Env:HOME = "C:\Users\<username>"

JUnit XML output

Yeti can output machine-readable JUnit XML suitable for use in Jenkins with the --junit option.

$ yeti --junit test/*.html > yeti.xml

Yeti will output XML on stdout and status messages on stderr.

When using Yeti several times in the same Jenkins job, it's useful to label tests with a prefix to distinguish between different Yeti runs after Jenkins merges the reports together. You can assign this prefix with the --name option.

$ yeti --name stable --junit test/stable/*.html > stable.xml
$ yeti --name flaky --junit test/flaky/*.html > flaky.xml

Code coverage

Yeti automatically includes a line coverage summary if your tests were instrumented with YUI Test Coverage.

✔ Testing started on Safari (6.0) / Mac OS
► Testing... \ 13% complete (10/60) 11.85 tests/sec ETA 4 minutes, 2 seconds 44% line coverage

AJAX testing

Yeti provides server-side AJAX routes with echoecho. Your test can make relative HTTP requests to test your code aganist server-side HTTP GET, POST, PUT, DELETE, OPTIONS, GET with delay, JSON or JSONP responses via POST, or any HTTP status code.

Example supported routes:

  • echo/status/500 returns a 500 response.
  • echo/delay/3 returns a 200 response after 3 seconds.
  • echo/jsonp?callback=foo returns a JSONP response with the given POST data wrapped in a call to foo.

Note these routes are intentionally relative paths. See the echoecho README for more details.


Yeti will move on to the next test if a test takes longer than 5 minutes (300 seconds). You can adjust this interval with the --timeout option.

This will run Yeti with a 120 second timeout:

$ yeti --timeout 120 test.html

There isn't a general timeout setting. Yeti actively pings browsers about every 2-5 seconds and disconnects them if they fail to respond to a ping three times.

Query string parameters

You can specify query string parameters to add to your test URLs. This can be used to pass information to your tests that control its behavior.

This will append ?filter=coverage to your tests, which is used by the tests for the YUI Library to trigger loading instrumented code.

$ yeti --query 'filter=coverage' test/*.html

Error handling

Yeti will report an uncaught exceptions as Script Errors.

Yeti enforces No-Quirks Mode in your tests because it may impact DOM-related APIs. Add a DOCTYPE to your test document to fix this.

Mobile testing made easy

When combined with localtunnel, mobile testing is simple. If you're not dealing with sensitive information, startup your Yeti Hub and then run:

$ localtunnel 9000
   Port 9000 is now publicly accessible from http://3z48.localtunnel.com ...

You can then visit that URL on your mobile (or any other) device and have it run new tests.

Yeti Hub

To save time, start a Yeti Hub.

$ yeti --server
Yeti Hub listening on port 9000.

Point browsers at your local Yeti on port 9000. Now, you're ready to run tests without having to reconnect browsers each time.

Starting Yeti in another terminal will connect to that Hub instead of starting a new one and will begin testing immediately if browsers are already connected.

$ yeti test/*.html
Connected to http://localhost:9000
  Agent connected: Chrome (22.0.1221.0) / Mac OS
  Agent connected: Safari (6.0) / Mac OS
✔ Testing started on Chrome (22.0.1221.0) / Mac OS, Safari (6.0) / Mac OS
✔ Agent completed: Chrome (22.0.1221.0) / Mac OS
✔ Agent completed: Safari (6.0) / Mac OS
504 tests passed! (11.5 seconds)


Your Yeti Hub can be shared with other developers.

First, I'll start a Hub on test.yeti.cx on port 80.

$ yeti --server --port 80

Go ahead and point a few browsers there.

Now, others can connect to it from their computer like so:

$ yeti --hub http://test.yeti.cx/ test/*.html
Connected to http://test.yeti.cx/
Waiting for agents to connect at http://test.yeti.cx/.
When ready, press Enter to begin testing.

Your pwd and your test file will be served through the Hub. Like magic.

[Hit Enter]
  Agent connected: Chrome (22.0.1221.0) / Mac OS
  Agent connected: Safari (6.0) / Mac OS
✔ Testing started on Chrome (22.0.1221.0) / Mac OS, Safari (6.0) / Mac OS
✔ Agent completed: Safari (6.0) / Mac OS
✔ Agent completed: Chrome (22.0.1221.0) / Mac OS
504 tests passed! (8.7 seconds)

This makes it really simple to setup an ad-hoc testing lab shared with your team.

Browser launching

You can specify the wd-hub option to connect Yeti to a Selenium 2 Hub using the WebDriver protocol. Specifying one or more browser options will cause Yeti to launch the given browsers over WebDriver.

For example, you can start a Yeti Hub like this:

yeti --server --wd-url http://selenium.example.com:4444

Then run tests on two Chrome browsers like this:

yeti --browser chrome --browser chrome test.html

Or, use the caps option to specify Selenium capabilities:

yeti --caps "platform=OS X 10.8;version=7;device-orientation=portrait;app=safari;device=iPhone Simulator" test.html

Valid options for browser include:

  • Chrome
  • IE (expands to Internet Explorer)
  • Firefox
  • Safari
  • PhantomJS
  • Android
  • iPad (for Sauce Labs)
  • iPhone (for Sauce Labs)

You can specify a platform for desktop browsers by specifying the desired platform after a slash /, e.g. chrome/xp. Valid platforms include:

  • Windows
  • XP
  • Mac
  • Linux
  • Vista
  • Windows XP (for Sauce Labs)
  • Windows 7 (for Sauce Labs)
  • Windows 8 (for Sauce Labs)
  • OS X 10.6 (for Sauce Labs)
  • OS X 10.8 (for Sauce Labs)


Here's a breakdown of all available CLI options.

  • query (String) Query string parameters to pass to tests.
  • timeout (Number in seconds) Test timeout.
  • hub (URL) Location of the Yeti Hub to use. Set to false or specify --no-hub to override a configuration file.
  • server Starts a Yeti Hub.
  • port (Number) Yeti Hub will listen to this port.
  • loglevel (debug or info) Print debugging information.
  • browser (String) Browser to launch with WebDriver. Requires a Hub with a wd-host and wd-port configured.
  • wd-url (URL) WebDriver Hub URL. May contain a username and password.
  • help Print usage.
  • version Print the Yeti version.

Configuration file

You may use place JSON in a .yeti.json file to set project or user specific configuration.

Yeti will look for .yeti.json in these places:

  • Recursively starting in the directory you start Yeti
  • In your home folder

Here is an example .yeti.json for the YUI project, which is placed in the repository root:

    "hub": "http://test.yeti.cx/",
    "basedir": ".",
    "glob": "**/tests/unit/*.html"

Here is the breakdown of these settings:

  • The hub option defines a Yeti Hub URL to use.
  • The basedir option indicates that the directory where .yeti.json lives is permitted to serve files to the Yeti Hub.
  • The glob option defines a pattern to search for test files.

These settings let YUI developers simply run yeti inside of the project directory to run tests. Since all tests in the project match the glob pattern, the yeti command works for specific components as well as for the entire project.

This configuration can be overridden on the command line. For example, to ignore the hub setting, you can run Yeti with --no-hub.

Yeti API

You can require("yeti") inside your application to script Yeti for your own use.

For API documentation:

  • Run make html to build HTML documentation to ./build_docs.
  • Review code comments inside lib/yeti.js, lib/client.js and lib/hub/index.js.

Yeti follows Semantic Versioning but is currently at a 0.x.y release. The public API is not stable. There will be changes.

Client-Side Yeti Integration

Yeti typically automates test frameworks, but you can integrate any client-side test or performance framework into Yeti. Combined with the Yeti API, you can easily build your own automation tools. YUI uses Yeti in this way to automate performance benchmarks.

Normally Yeti will scan pages in order to find test frameworks. When serving a page to Yeti, you can set window.stopYetiScan to true to signal that your page will explicitly submit results to Yeti.

When your framework has results and is ready to move to the next page, you can call window.sendYetiResults with an object containing data to report. This data will be passed through verbatim to the Node.js Yeti API for further processing in your tool.



Yeti should work on all platforms supported by Node.js. It's tested on Linux and OS X.

Serving tests

You must start Yeti's client in the directory you'll be serving tests from. For security reasons, Yeti will reject requests that try to access files outside of the directory you start Yeti in.

Install latest Yeti snapshot

You can install the latest development snapshot of Yeti easily:

npm install -g http://latest.yeti.cx

This will install Yeti as it exists on the yui/yeti GitHub repository. You can check the stability of the Yeti snapshot by checking yui/yeti on Travis.

Develop Yeti

Do you want to add new features or fix bugs in Yeti itself? We made it easy for you to hack on Yeti.

Experimental: Develop on Windows

After running npm install, replace the make commands below with .\jake.bat to use the experimental Jake tasks that are Windows ready.


Install dependencies

Clone Yeti.

git clone https://github.com/yui/yeti.git
cd yeti

Install Yeti's dependencies.

npm install

Run tests & code coverage

Yeti's automated tests require PhantomJS. You can download PhantomJS source or pre-built binaries from their website. Make sure the phantomjs binary is installed in your PATH.

make test
make coverage

The latter command uses JSCoverage for Node.js, which will be built and installed to ./tools/jscoverage.


make lint

You may also run the linter on individual files with ./go lint:

./go lint test/blizzard.js

Yeti uses JSHint to analyze code for problems. See .jshintrc for options used by Yeti.


Requires Google Chrome Canary and OS X.

Profile the Yeti Hub:

./go profile --server

Using ./go profile without --server to profile the Yeti client requires an interactive terminal, which does not yet work.

HTML documentation


Yeti uses Selleck to generate its website. Selleck files are located in doc/.

make html

Documentation will be built to build_docs/.

JavaScript API

Yeti uses YUIDocJS to generate API documentation from inline JSDoc comment blocks.

make html-api

Documentation will be built to build_docs/api/everything/.

Contribute to Yeti


Bugs & Feedback

Open a ticket on YUILibrary.com's Yeti Issue Tracker to report bugs or feature requests.


Yeti is free to use under YUI's BSD license. See the LICENSE file or the YUI license page for license text and copyright information.