private function doTest(\Closure $c)
 {
     foreach (array('Salt' => CryptTool::createInstance(CryptTool::TYPE_SALT), 'Sodium' => CryptTool::createInstance(CryptTool::TYPE_SODIUM)) as $key => $instance) {
         if ($instance === null) {
             echo $key . ": could not instance crypt tool\n";
             break;
         }
         /** @noinspection PhpUndefinedMethodInspection */
         $this->assertTrue($instance->isSupported(), $key . ' not supported');
         $c->__invoke($instance, $key);
     }
 }