How to install an updated version of PEAR / PHPUnit on Ubuntu

First, install PEAR.
sudo apt-get install php-pear
Next, tell PEAR to update its own channel.
sudo pear channel-update pear.php.netThen, tell PEAR to upgrade itself to the newest version.
sudo pear upgrade-allYou should now have the newest version of PEAR installed.
To install PHPUnit, let PEAR know where to find PHPUnit.
sudo pear channel-discover pear.phpunit.deThen install PHPUnit. (the -a makes sure all dependency packages are also installed)
sudo pear install -a phpunit/PHPUnit