Manual:PHP unit testing

Unit testing in MediaWiki is performed using the PHPUnit framework.

The unit tests are located in the tests/phpunit directory. Tests are organized into a directory structure that matches the directory structure of the code that they are testing. For example: The unit tests for file includes/IP.php can be found in tests/phpunit/includes/IP.php.

Installing PHPUnit
To run the unit tests, PHPUnit must be installed.

On Unix-like operating systems, run  from the tests/phpunit directory. This will attempt to install PHPUnit using PEAR, falling back to the apt and yum package managers if PEAR is not available.

On Windows-family operating systems, follow the installation instructions in the PHPUnit manual.

Running the unit tests
Run the unit tests from the command line, ensuring that you are in the tests/phpunit directory.
 * On UNIX-like operating systems, run either php phpunit.php or  . To see options for running the tests, run.
 * On Windows-family operating systems, run the   batch file.

Writing unit tests
The PHPUnit Manual provides good instructions for understanding and developing unit tests. Pay particularly close attention to the sections on writing and organizing tests.

Developers new to unit testing in MediaWiki should use SampleTest.php as a starting point – it contains helpful comments that will ease the process of learning to write unit tests.

Another resource is the slides PHPUnit Best Practices talk that Sebastian Bergmann gave at OSCON 2010.

Write Testable Code
MediaWiki was not written with the objective of being testable. It uses global variables all over the place and static methods in many places. This is a legacy that we have to accept, but try not to introduce these things into new code. A good resource might be Miško Hevery's Guide to Testability. (Miško Hevery is [one of?] Google's Agile Coach)

Telling a story
Test output should tell a story (output options).

Number of Assertions
Only one assertion per test unless there is a good reason (expensive tests may need to be grouped).

Grouping tests
PHPUnit allows tests to be put into arbitrary groups. Groups of tests can be selected for execution or excluded from execution when the test suite is run (see the @group annotation, The Command-Line Test Runner and XML Configuration File documentation in the PHPUnit manual for additional details.)

To add a test (or class) to a group, use the  annotation in the docblock preceding the code. For example:

""

Eight groups are currently used in the MediaWiki unit tests:
 * Broken: Put broken tests into group Broken. Tests in this group will not be run (as is configured in tests/phpunit/suite.xml).
 * Database: Tests that require database connectivity should be put into group Database.
 * Destructive: Tests that alter or destroy data should be put into group Destructive.
 * Search: Tests that use MediaWiki's built-in search put into group Search.
 * SeleniumFramework: Tests that require SeleniumFramework to be installed should be put in group SeleniumFramework.
 * Stub: Put test stubs into group Stub. Tests in this group will not be run (as is configured in tests/phpunit/suite.xml).
 * sqlite: Tests that use SQLite should be put into group sqlite.
 * Upload: Tests that upload files should be put into group Upload.
 * Utility: Currently unused by any test. Tests in this group will be not be run (as is configured in tests/phpunit/suite.xml).

Developing best practices
Developers should avoid inventing new conventions or borrowing conventions from other frameworks; using the already well-established PHPUnit conventions will serve to make MediaWiki's tests both useful and usable. Pay particularly close attention to the sections in the PHPUnit manual on writing and organizing tests.