PHPUnit Compatibility and WordPress Versions

Changes to supported PHPUnit versions have been as followed:

• In WordPress 4.4: Added support for PHPUnit 5 was added on PHPPHP The web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher 7.0.
• In WordPress 4.7: Added support for PHPUnit 6 on PHP 7.0 and 7.1.
• In WordPress 5.1: Added support for PHPUnit 7 on PHP 7.1, 7.2, and 7.3. PHP 7.0 remains at PHPUnit 6.
• In WordPress 5.2: Added support for PHPUnit 7 on PHP 7.0, and PHPUnit 5 on PHP 5.6.
• In WordPress 5.9: Added a dependency on the external PHPUnit Polyfills, which enabled support for PHPUnit 8 and 9, making it so the tests can now run on the most appropriate PHPUnit version for each PHP version.

Supported Version Chart

WP | PHP Version	5.2	5.3	5.4	5.5	5.6	7.0	7.1	7.2	7.3	7.4	8.0
5.9	x	x	x	x	5	6	7	8	9	9	9
5.8	x	x	x	x	5	5	7	7	7	7	7*
5.7	x	x	x	x	5	5	7	7	7	7	7*
5.6	x	x	x	x	5	5	7	7	7	7	7*
5.5	x	x	x	x	5	5	7	7	7	7	x
5.4	x	x	x	x	5	5	7	7	7	7	x
5.3	x	x	x	x	5	5	7	7	7	7	x
5.2	x	x	x	x	5	5	7	7	7	x	x
5.1	3.6	4	4	4	4	6	7	7	7	x	x
5.0	3.6	4	4	4	4	6	6	6	6	x	x
4.9	3.6	4	4	4	4	6	6	6	x	x	x
4.8	3.6	4	4	4	4	6	6	x	x	x	x
4.7	3.6	4	4	4	4	6	6	x	x	x	x
4.6	3.6	4	4	4	4	5	x	x	x	x	x
4.5	3.6	4	4	4	4	5	x	x	x	x	x
4.4	3.6	4	4	4	4	5	x	x	x	x	x
4.3	3.6	4	4	4	4	x	x	x	x	x	x
4.2	3.6	4	4	4	4	x	x	x	x	x	x
4.1	3.6	4	4	4	4	x	x	x	x	x	x
4.0	3.6	4	4	4	x	x	x	x	x	x	x
3.9	3.6	4	4	4	x	x	x	x	x	x	x
3.8	3.6	4	4	4	x	x	x	x	x	x	x
3.7	3.6	4	4	4	x	x	x	x	x	x	x

* The coreCore Core is the set of software required to run WordPress. The Core Development Team builds WordPress. test suite currently runs a modified version of PHPUnit 7 (which on its own is not compatible) on PHP 8. See #50902 for more information.

Last updated: August 24, 2021