public function apply(PHPUnit_Util_Metrics $metrics)
 {
     $coverage = $metrics->getCoverage();
     if ($coverage <= $this->threshold[0]) {
         $violation = 'The code coverage is %01.2F which is considered low.';
     } else {
         if ($coverage > $this->threshold[0] && $coverage < $this->threshold[1]) {
             $violation = 'The code coverage is %01.2F which is considered medium.';
         }
     }
     if (isset($violation)) {
         return sprintf($violation, $coverage);
     }
 }