Manual:JavaScript unit testing

MediaWiki uses [ https://qunitjs.com/ QUnit] to unit test its JavaScript code base.

Run from a browser

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

One-time setup
Enter an isolated environment where you have Node.js and npm. [ https://timotijhof.net/posts/2019/protect-yourself-from-npm/ Why?]

If using MediaWiki-Docker:


 * Consider using Fresh
 * Run from the MediaWiki core directory. ( Fresh automatically finds the MW address in Docker's  file. )
 * Once inside your isolated shell, run to install or update any dependencies.

If using MediaWiki-Vagrant:


 * Ensure environment variables and  are set (consider saving this to  ):
 * Run from the MediaWiki-Vagrant directory.
 * Once inside the Vagrant VM. navigate to the MediaWiki core directory and run.

If using a different setup:


 * Ensure environment variables and  are set (consider saving this to  ):
 * Consider using Fresh, or if you have an isolated environment already, ensure a comparable version of Node.js and npm are installed (the before-last LTS should do).
 * Navigate to the MediaWiki core directory and run.

Run
This runs the QUnit tests in Headless Chrome:

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

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

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

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

Write a test
It is the convention to name the test suite file after the module it covers. For example,  covers the   module.

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

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

MediaWiki core
Test suites are added to the registration of the module in.

Tests are organised into a directory structure that matches the directory structure of the code being tested. For example: The unit test for can be found at.

Example:

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