Clone into phpBB/ext/acme/demo:
$ git clone https://github.com/phpbb/phpbb-ext-acme-demo.git phpBB/ext/acme/demo
Go to "ACP" > "Customise" > "Extensions" and enable the "Acme Demo Extension" extension.
We use Travis-CI as a continous integration server and phpunit for our unit testing. See more information on the phpBB development wiki. 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\acme\demo\phpunit.xml.dist
others:
phpBB/vendor/bin/phpunit -c phpBB/ext/acme/demo/phpunit.xml.dist