WP Core Tests vs PHP 8.1 Juliette Reinders Folmer Tweet about it: @jrf_nl 

Current Situation ▪ Composer "phpunit/phpunit": "^7.5" ▪ Composer lock file Continuous Integration: ▪ PHP 5.6, 7.0: Use PHPUnit 5.7 Phar ▪ PHP 7.1 – 7.4: Use PHPUnit 7.5 Phar ▪ PHP 8.0: Use Composer install with –ignore-platform-reqs Copied in PHPUnit 9.x MockObject files 

The Problem With the Current Setup Testing locally against different PHP versions PHP 8.1 Maintenance burden 

PHPUnit Support v Compatible with: 10 PHP >= 8.0 (expected end of 2021) 9 PHP >= 7.3 8 PHP >= 7.2 7 PHP 7.1, 7.2, 7.3 [EOL] 6 PHP 7.0, 7.1, 7.2 [EOL] 5 PHP 5.6, 7.0, 7.1 [EOL] Seemann 

Making Test Suites PHPUnit Cross-version Compatible Renamed/split assertion and expectation methods void return type for fixture methods (PHPUnit >= 8.0) Configuration file format change (PHPUnit >= 9.3) 

PHPUnit vs PHP PHPUnit / PHP 5.6 7.0 7.1 7.2 7.3 7.4 8.0 8.1 5.x 6.x 7.x 8.x 8.6+ ? 9.x 9.3+ 9.6+ ? 10.x void 8.5+ 

What Happened Last Year ? (PHP 8.0) Phar Version constraint 5.x PHPUnit version constraints Mocking Code Coverage Composer Version constraint 7.x --ignore-platform-reqs in CI Copied in files from PHPUnit 9.x Not available on PHP 8.0 

PHP 8.1 vs PHPUnit 7.x  Config file  PHPUnit 7.x + PHPUnit 7.x dependencies incompatible with PHP 8.1 (and won't be fixed anymore) 

Constraints and Wishes » Supporting PHP 5.6 + 7.0 still required » Plugin tests often extend WP integration test suite » Supporting both PHPUnit PHAR + Composer install preferred » Make running tests locally against different PHP versions easier for contributors 

WP native solution PHPUnit Polyfills Symfony Bridge Options 

PHPUnit Polyfills What you get: ▪ Polyfills via traits for all new assertions and expectations in PHPUnit ▪ Helper to work round removal of assertAttribute*() methods ▪ An cross-version compatible abstract base TestCase (to get round void) which includes all polyfills ▪ A cross-version compatible TestListenerImplementation Sponsored by: 

Action Plan ❑Remove composer.lock file ❑Use PHPUnit 9.x assertion and expectation methods ❑Solve void for fixtures ❑Remove old work-arounds ❑Enable testing against PHP 8.1 in CI ❑Fix any and all PHP 8.1 incompatibilities 

Follow Along ▪ Remove composer.lock https://core.trac.wordpress.org/ticket/47381 Patch: https://github.com/WordPress/wordpress-develop/pull/1511 ▪ Make test suite compatible with PHPUnit 8.x + 9.x https://core.trac.wordpress.org/ticket/46149 Patches not pulled yet: https://github.com/jrfnl/wordpress-develop- official/tree/WIP/all-stacked-in-the-right-order ▪ PHP 8.1 fixes https://core.trac.wordpress.org/ticket/53635 

Open Questions ▪ What to do about the Speedtrap listener package ? ▪ How to handle the stdClass / __invoke() warning ? ▪ Update the Core Test running and contributing docs 

Further Reading ▪ The Grumpy Programmer's Guide to Testing PHP Applications https://grumpy-learning.com/ ▪ Your Mocks Won't Save You! https://24daysindecember.net/2020/12/08/your-mocks-wont-save-you/ ▪ My Top 10 PHPUnit Tips & Tricks https://speakerdeck.com/jrf/my-top-10-phpunit-tips-and-tricks-e6ea54ce- 2515-4ea9-aacf-9bf7ab3b3141 ▪ PHPUnit Documentation https://phpunit.readthedocs.io/ ▪ Path Coverage in PHPUnit https://doug.codes/php-code-coverage 

Tooling ▪ PHPUnit Polyfills https://packagist.org/packages/yoast/phpunit-polyfills ▪ WP Test Utils https://packagist.org/packages/yoast/wp-test-utils 

Thanks! @jrf_nl @jrfnl Any questions ? Slides: https://speakerdeck.com/jrf