Zend_Log_Writer_Mock is a very simple writer that records
the raw data it receives in an array exposed as a public property.
$mock = new Zend_Log_Writer_Mock;
$logger = new Zend_Log($mock);
// [timestamp] => 2007-04-06T07:16:37-07:00
// [message] => Informational message
// [priority] => 6
// [priorityName] => INFO
To clear the events logged by the mock, simply set $mock->events = array().