public function testClearingInvalidCache()
 {
     $this->setExpectedException('Exception');
     Orm::configure('caching', true);
     Orm::configure('caching_driver', 'invalid');
     try {
         ORM::forTable('widget')->where('name', 'Fred')->where('age', 17)->findOne();
     } catch (Exception $e) {
         Orm::clearCache();
     }
 }