How to install an older version of PHPUnit through PEAR?

You need to know the exact version number you wish to downgrade to. At the time of writing, the last release you're after is 3.3.17, which can be found out by checking the appropriate PEAR channel.

To downgrade to that particular version execute two commands:

• pear uninstall phpunit/PHPUnit
• pear install phpunit/PHPUnit-3.3.17

Note that if you wish to downgrade from a 3.6.x release to 3.5.15 (final stable 3.x release), then you need to uninstall, then reinstall several dependencies manually. Otherwise pear will just force install the latest version of PHPUnit.

Here's how:

(Original instructions from Dusty Reagan's blog: http://dustyreagan.com/downgrade-phpunit-3-6-to-3-5-15/. duplicated to SO in case original link dies for some reason.)

First you need to uninstall PHPUnit 3.6 and all of it’s dependencies.

sudo pear uninstall phpunit/PHPUnit
sudo pear uninstall phpunit/DbUnit
sudo pear uninstall phpunit/PHP_CodeCoverage
sudo pear uninstall phpunit/File_Iterator
sudo pear uninstall phpunit/PHPUnit_MockObject
sudo pear uninstall phpunit/Text_Template
sudo pear uninstall phpunit/PHP_Timer
sudo pear uninstall phpunit/PHPUnit_Selenium
sudo pear uninstall pear.symfony-project.com/YAML

Next install these specific versions of each dependency, in this order, installing PHPUnit-3.5.15 last.

sudo pear install pear.symfony-project.com/YAML-1.0.2
sudo pear install phpunit/PHPUnit_Selenium-1.0.1
sudo pear install phpunit/Text_Template-1.0.0
sudo pear install phpunit/PHPUnit_MockObject-1.0.3
sudo pear install phpunit/PHP_Timer-1.0.0
sudo pear install phpunit/File_Iterator-1.2.3
sudo pear install phpunit/PHP_CodeCoverage-1.0.2
sudo pear install phpunit/DbUnit-1.0.0
sudo pear install phpunit/PHPUnit-3.5.15

Note: You may need to add channel for PHP_CodeCoverage, which doesn't seem to be obligatory for PHPUnit 3.6

sudo pear channel-discover components.ez.no
sudo pear install channel://components.ez.no/ConsoleTools-1.6