Manual:JavaScript unit testing

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MediaWiki uses QUnit to unit test its JavaScript code base.

Run from a browser

Set $wgEnableJavaScriptTest to true.
This is already set in most developer environments, like Quickstart or MediaWiki-Docker .
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.

Run

This runs the QUnit tests in Headless Chrome:

$ npm run qunit

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

 mediawiki.util
     ✔ escapeRegExp
     ✔ debounce
 …

 Finished in 5.42 secs

 SUMMARY:
 ✔ 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

  testrunner
    ✔ Loader status
    ✔ assert.htmlEqual
  ext.growthExperiments.Utils.js
    ✔ serializeActionData
    ✔ isUserInVariant
  ext.growthExperiments.Help/HelpPanelProcessDialog.js
    ✔ getDefaultPanelForSuggestedEditSession for copyedit
    ✔ updateEditMode for link-recommendation
    ✔ updateEditMode for copyedit, isEditing
  ext.growthExperiments.Homepage.SuggestedEdits/PagerWidget.js
    ✔ constructor
    ✔ setMessage with currentPosition < totalCount
    ✔ setMessage with currentPosition === totalCount
    ✔ setMessage with currentPosition > totalCount
  ext.growthExperiments.NewcomerTaskLogger.js
    ✔ constructor
    ✔ should log impressions
    ✔ should get log metadata
  ext.growthExperiments.StructuredTask/addimage/AddImageUtils.js
    ✔ 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

SUMMARY:
✔ 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). Why?

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.

Inside the test suite should be a call to QUnit.module with the module name.

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.

Example:

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

Extensions

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