Make WordPress Core

Opened 2 months ago

Last modified 6 days ago

#53010 new task (blessed)

Tests: introduce namespacing for the test classes

Reported by: jrf Owned by:
Milestone: Awaiting Review Priority: normal
Severity: normal Version:
Component: Build/Test Tools Keywords:
Focuses: docs, coding-standards Cc:

Description (last modified by jrf)

Introducing namespaces in the production code for WordPress Core is a hot topic, so I very purposely do NOT want to touch that in this ticket.

However, for the test suite, which doesn't get shipped with the WordPress production code, it's a whole other matter.


Using namespaces in the test suite provides us with the following benefits:

  1. If used consistently and providing they follow a set pattern (more about this below), they will make it very easy for contributors to find the test files/classes they are looking for.
  2. It will allow for shorter file and test class names, while those will still be descriptive.
  3. And... it will allow for mocking PHP native functions by declaring a namespaced version of that same function in the test class.
  4. It will also allow more easily for multiple test classes to be created to test one particular feature/function, which the current naming scheme does not allow for. This will allow for tests for the same functionality, but which need different fixtures (setup/teardown) to be encapsulated in their own test classes.


As the WordPress Core test suite is used not only by Core, but also by plugins and themes for integration tests, the test class namespacing should be reserved for actual test classes and - for now - not be applied to test utility classes / Abstract base test classes (i.e. the tests/phpunit/includes directory should NOT be touched for now).

Proposed pattern

The current directory structure for tests is, to put it mildly, confusing and inconsistent.

To solve that, I would like to propose the following pattern:

  • File paths: tests/phpunit/tests/wp-[includes|admin]/[SubFolder/]*Class_Under_Test/FunctionUnderTest[OptionalSubsetIndicator]Test.php
  • Namespace: WordPress\Tests\WP_[Includes|Admin]\[SubFolder\]*Class_Under_Test
  • Classname: FunctionUnderTest[OptionalSubsetIndicator]Test

For WP Core files which only contain functions outside of a class structure, the following pattern is proposed:

  • File paths: tests/phpunit/tests/wp-[includes|admin]/[SubFolder/]*Functions_FileName/FunctionUnderTest[OptionalSubsetIndicator]Test.php
  • Namespace: WordPress\Tests\WP_[Includes|Admin]\[SubFolder\]*Functions_FileName
  • Classname: FunctionUnderTest[OptionalSubsetIndicator]Test

The pattern I'm proposing does imply a re-organisation of the test suite directory and file structure, but that IMO is for the better.

It also follows a PSR4-like pattern which will be more intuitive for new contributors to work with, as well as follow the PHPUnit recommended test class name pattern with having the Test as the end of the class name.

This will also allow for using PSR-4 autoloading for the tests classes and adding the autoload-dev directive to the composer.json file.


This should be regarded as a small project and not all renaming needs to be done at the same time.

New tests should start following the above proposed pattern as soon as consensus has been reached about this proposal.
Existing tests can be gradually switched over to the new pattern over time.

Additional tasks associated with this project

  • [ ] Updating the contributors handbook for Core.
  • [ ] Verify that the WordPressCS sniffs will validate this pattern correctly.
  • [ ] Write a Make post about the decision once consensus has been reached.

Change History (6)

#1 @jrf
2 months ago

  • Description modified (diff)

#2 @jrf
2 months ago

  • Description modified (diff)

#3 @johnbillion
2 months ago

  • Version trunk deleted

This ticket was mentioned in Slack in #core by ayesh. View the logs.

2 months ago

#5 @jrf
6 days ago

Note: this proposal to follow PSR4 for the tests becomes all the more relevant once the test suite needs to start supporting PHPUnit 9.x.

PHPUnit 9.1.0 deprecated support for test file names which do not match the class name of the test class within.

It also deprecates the use of multiple (test) classes within a file, though I don't think that's used in WP.

Ref: https://github.com/sebastianbergmann/phpunit/pull/4109/

#6 @jrf
6 days ago

I've opened https://github.com/WordPress/WordPress-Coding-Standards/issues/1995 to adjust the WordPress Coding Standards for the above.

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