[WP documentation](https://make.wordpress.org/core/handbook/testing/automated-testing/phpunit/) says > WordPress is currently only compatible with the 7.x release tree frozzare/wp-test-suite[v1.1.0, ..., v1.1.1] requires phpunit/phpunit ~5.0. We need to upgrade the test-suite
WP documentation says
frozzare/wp-test-suite[v1.1.0, ..., v1.1.1] requires phpunit/phpunit ~5.0.
We need to upgrade the test-suite