public function requireNoClasses($classNames, $testDetails)
    {
        $this->testing($testDetails);
        $badClasses = array();
        foreach ($classNames as $className) {
            if (class_exists($className)) {
                $badClasses[] = $className;
            }
        }
        if ($badClasses) {
            $message = $testDetails[2] . ".  The following classes are at fault: " . implode(', ', $badClasses);
            $this->error($testDetails, $message);
            return false;
        }
        return true;
    }