WordPress PHPUnit test setup

Get a real WordPress integration test harness running for a plugin or theme. The fast path is WP-CLI's scaffolder, which generates the same layout WordPress core uses. This skill is the setup + CI half; writing the actual tests is wp-phpunit-writing-tests.

When to use this skill

• Adding automated tests to a plugin/theme that has none.
• Wiring PHPUnit into CI (GitHub Actions, GitLab, etc.).
• Debugging install-wp-tests.sh, the test database, tests/bootstrap.php, or "wrong PHPUnit version" errors.
• Reviewing a repo's phpunit.xml.dist, composer.json test scripts, or CI matrix.

The PHPUnit version reality (read this first)

The most common setup mistake: requiring PHPUnit 10 or 11 for a WP_UnitTestCase integration suite. WordPress 7.1's core test library remains on PHPUnit 9.x: the official matrix assigns PHPUnit 9 to WordPress 7.1 on PHP 7.4 through 8.5, and core's phpunit.xml.dist uses the PHPUnit 9.2 schema. Check the official compatibility table for each WordPress/PHP branch instead of extrapolating from the newest PHP.