All tests can be run from the src/test/php directory by running:
$ phpunit

Tests classes are divided into groups which can be run individually:
$ phpunit --group main
$ phpunit --group appenders
$ phpunit --group configurators
$ phpunit --group filters
$ phpunit --group helpers
$ phpunit --group layouts
$ phpunit --group renderers

Individual test classes can be run using e.g.:
$ phpunit appenders/LoggerAppenderSocketTest.php

When using relative paths in the tests, be aware that "mvn test" does a
changedir to this directory. So dirname(__FILE__).'/../../' is preferred.