Copy the extension to phpBB/ext/mattf/test
Go to "ACP" > "Customise" > "Extensions" and enable the "Test" extension.
We use Github Actions as a continuous integration server and phpunit for our unit testing. See more information on the phpBB Developer Docs. To run the tests locally, you need to install phpBB from its Git repository. Afterwards run the following command from the phpBB Git repository's root:
Windows:
phpBB\vendor\bin\phpunit.bat -c phpBB\ext\mattf\test\phpunit.xml.dist
others:
phpBB/vendor/bin/phpunit -c phpBB/ext/mattf/test/phpunit.xml.dist