These guides tell you to install PHPUnit using pear, but this method is disabled as of Dec 2014.
I was finally able to get PHPUnit installed using the commands from this answer and now I can actually check my
phpunit --version, which is
PHPUnit 4.6.7 by Sebastian Bergmann and contributors.
The error that I am getting stuck at now is this:
require_once(): Failed opening required 'SymfonyComponents/YAML/sfYaml.php'
This SO Answer says that the test framework is wanting to use the Symfony 1 version of the YAML module. I cannot find this old version anywhere, so it made me wonder if there isn't something I'm overlooking. I have already tried the Official SVN repo but it just times out.
Edit: I guess there was some issue with their servers yesterday. Today it is working and I was able to install the necessary YAML module using this command:
sudo pear install symfony/YAML
I'm not really sure if this could be considered a "question" anymore, but I feel it is a good reference for others who might want to install the test framework.