Install PEAR

Run command prompt as a administrator, now switch to the directory where you installed PHP by running:

cd c:\xampp\php\

Then install PEAR by running:

pear.bat

Install PHPUnit

Run the following commands one by one:

pear channel-update pear.php.net
pear upgrade-all
pear channel-discover pear.phpunit.de
pear channel-discover components.ez.no
pear channel-discover pear.symfony-project.com
pear update-channels
pear install --alldeps --force phpunit/PHPUnit

To test the PHPUnit, run:

phpunit -v