I have had to de- and reinstall a newer version of PHPUnit following these directions. Now when I\'m launching this line
sudo pear install --alldeps phpunit/PHPU
I had the same problem while upgrading my phpunit.
This solved the problem:
pear channel-discover pear.symfony.com
pear install pear.symfony.com/Yaml
Then run:
pear install --alldeps pear.phpunit.de/PHPUnit
OBS: I think the pear install pear.symfony.com/Yaml
is not necessary. I'm just posting it because it is exactly the way I solved my problem.