public function testSetFilter()
 {
     $appender = new LoggerAppenderEcho("LoggerAppenderTest");
     $layout = new LoggerLayoutSimple();
     $appender->setLayout($layout);
     $filter = new LoggerFilterDenyAll();
     $appender->addFilter($filter);
     $filter2 = new LoggerFilterLevelMatch();
     $appender->addFilter($filter2);
     $first = $appender->getFilter();
     self::assertEquals($first, $filter);
     $next = $first->getNext();
     self::assertEquals($next, $filter2);
     $appender->clearFilters();
     $nullfilter = $appender->getFilter();
     self::assertNull($nullfilter);
 }