Manual:JavaScript unit testing

Jump to navigation Jump to search
MediaWiki's QUnit test suite running in Chrome.

MediaWiki uses QUnit to unit test its JavaScript code base.

Run from a browser[edit]

  1. Set $wgEnableJavaScriptTest to true. (This is already set if you use MediaWiki-Docker-Dev or MediaWiki-Vagrant.)
  2. Visit Special:JavaScriptTest in a browser to run the tests.

Run from the command line[edit]

Getting started[edit]

  1. Enter an isolated environment where you have Node.js and npm installed. Why?
    • For MediaWiki-Vagrant, ssh to your Vagrant VM.
    • For MDD or other, consider Fresh. Run fresh-node -net -env.
  2. Run npm ci from the MediaWiki directory.


This runs the QUnit tests in Headless Chrome and prints the results.

$ npm run qunit

Running "karma:main" (karma) task
INFO [launcher]: Starting browser ChromeHeadless
    ✔ escapeRegExp
    ✔ debounce
Finished in 5.659 secs / 5.442 secs

✔ 440 tests completed


How to help?[edit]

Run tests before committing[edit]

Make it a habit to run unit tests before committing and submitting your changes to Gerrit.

Write unit tests[edit]

Always write unit tests for new functionality. We're also looking to expand our unit test coverage of already existing modules in the MediaWiki JavaScript library.

Write a test[edit]

It is the convention to name the test suite file after the module it covers. For example, mediawiki.user.test.js covers the mediawiki.user module.

Inside the test suite should be one, and only one, call to QUnit.module with the module name.

The unit tests for MediaWiki core are located in the tests/qunit/suites directory.

Register a test[edit]

MediaWiki core[edit]

Test suites are added to the registration of the mediawiki.tests.qunit.suites module in /tests/qunit/QUnitTestResources.php.

Tests are organised into a directory structure that matches the directory structure of the code being tested. For example: The unit test for resources/mediawiki.util/mediawiki.util.js can be found at tests/qunit/suites/resources/mediawiki.util/mediawiki.util.test.js.


 'mediawiki.tests.qunit.suites' => array(
 	'scripts' => array(
+		'tests/qunit/suites/resources/mediawiki/mediawiki.example.test.js',
 	'dependencies' => array(
+		'mediawiki.example',


Extensions register their QUnit tests via the ResourceLoaderTestModules hook.

See also[edit]