PhpUnit weird behaviour

Hello, I've been playing around with PHPUnit and found a weird behaviour. My main class derives from PEAR and has the following method function _readConf() { if (is_array($this->_conf) && sizeof($this->_conf) > 0) { return true; } // if include_once CGTL_METADATA_DIR . 'internet/' . $this->_id . '.conf'; if (!isset($conf) || !is_array($conf)) { return false; } // if $this->_conf = $conf; return true; } // end func _readConf the Testcase has two tests which calls an init() method which calls the _readconf()method. If i have just one test it works fine. When i add a second test _readconf() keeps returning FALSE. The problem does not arise when i use include instead of include_once. I don't understand why it does that, does anybody has an idea ? If I was not clear do not hesitate to ask. Arnaud.