Just a copy& paste guide:
#install pear, phpunit sudo apt-get install php-pear phpunit #upgrade pear - this is necessary sudo pear upgrade PEAR #install phpunit sudo pear config-set auto_discover 1 sudo pear install pear.phpunit.de/PHPUnit
All done! Now you can run symfony tests:
cd vendor/symfony
php vendors.php
phpunit -c phpunit.xml.dist tests/