I had the annoying message about modules missing when I upgraded to Natty (or even Maverick?) and started Googling it.
I was not alone but the maintainers seems to not care so people was going around it. They tended to try to get the existing phpunit package running by adding pear pacages like mads..
I did that aswell, once. And got borded. Instead I downloaded an old phpunit package and installed it. And then Ubuntu found out there was a new one and wanted to upgrade to that, which we now know, is broken.
So, we download and then stop apt to upgrade.
cd /tmp wget http://no.archive.ubuntu.com/pool/universe/p/phpunit/phpunit_3.4.13-1_all.deb sudo dpkg -i phpunit_3.4.13-1_all.deb sudo echo phpunit hold | dpkg --set-selections
Then it will stick. You’ll have an older version, 3.4 instead of 3.5 but at least it works.