Manual:JavaScript unit testing/dtp

This page is a translated version of the page Manual:JavaScript unit testing and the translation is 5% complete.
Tiis suite MediaWiki QUnit.

MediaWiki uses QUnit to unit test its JavaScript code base.

Run from a browser

  1. Set $wgEnableJavaScriptTest to true.
    This is already set in most developer environments, like Quickstart or MediaWiki-Docker .
  2. Visit Special:JavaScriptTest in a browser to run the tests.

Run from the command line

One-time setup

  • Set the environment variables MW_SERVER and MW_SCRIPT_PATH to the URL of your local wiki. You can also put these in a .bash_profile file in your home directory to automatically set load variables in new Terminal tabs.
    # MediaWiki-Docker
    export MW_SERVER=http://localhost:8080
    export MW_SCRIPT_PATH=/w
    # composer serve
    export MW_SERVER=http://localhost:4000
    export MW_SCRIPT_PATH=/
  • Navigate to the MediaWiki core directory and run npm ci.


This runs the QUnit tests in Headless Chrome:

$ npm run qunit

Running "karma:main" (karma) task
 INFO [launcher]: Starting browser ChromeHeadless

     ✔ escapeRegExp
     ✔ debounce

 Finished in 5.42 secs

 ✔ 440 tests completed

You can run QUnit tests for specific components with the --qunit-component option. Pass the name of an extension or skin, or MediaWiki for MediaWiki core tests.

$ node_modules/grunt/bin/grunt qunit --qunit-component=GrowthExperiments

Running "karma:main" (karma) task

INFO [launcher]: Starting browser ChromeHeadless

    ✔ Loader status
    ✔ assert.htmlEqual
    ✔ serializeActionData
    ✔ isUserInVariant
    ✔ getDefaultPanelForSuggestedEditSession for copyedit
    ✔ updateEditMode for link-recommendation
    ✔ updateEditMode for copyedit, isEditing
    ✔ constructor
    ✔ setMessage with currentPosition < totalCount
    ✔ setMessage with currentPosition === totalCount
    ✔ setMessage with currentPosition > totalCount
    ✔ constructor
    ✔ should log impressions
    ✔ should get log metadata
    ✔ getRenderData: target width < original width
    ✔ getRenderData: the image file needs to be re-rasterized
    ✔ getRenderData: vector image
    ✔ getRenderData: target width > original width
    ✔ getRenderData: 3x target width
    ✔ getRenderData: 2.5x target width
    ✔ getRenderData: vertical image with landscape viewport
    ✔ getRenderData: with specified render width

Finished in 0.03 secs

✔ 46 tests completed

You can use the --qunit-watch argument for QUnit to watch the files associated with a component, and automatically re-run tests when those files change.

Security consideration

Consider using Fresh, or if you have another isolated environment already, ensure a comparable version of Node.js and npm are installed (the before-last Node.js LTS is recommended).


  • To enter the isolated environment, run fresh-node -net -env from the MediaWiki core directory. (Fresh automatically finds the MW_SERVER and MW_SCRIPT_PATH variables from MediaWiki-Docker's .env file.)
  • Once inside your isolated shell, run npm ci to install or update any dependencies.
  • To start the tests, run npm run qunit.

How to contribute?

Run tests before committing

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

Write unit tests

Write unit tests for new functionality, and consider fillling gaps in coverage when changing existing modules in MediaWiki core.

Write a test

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.

Suang do tiis suite minog do haro pamalahawan kumaa QUnit.module miampai do ngaran modul.

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

Register a test

MediaWiki core

Test suites are added to the registration of the test.MediaWiki 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.base/util.js can be found at tests/qunit/resources/mediawiki.util/util.test.js.


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


Extensions register their QUnit tests via the QUnitTestModule attribute in extension.json.

See also