Added security: whitelist the keys we'll accept from `$comment_meta['tests']`:
 
```php
$footstep = (object) array_replace( 
  (array) $footstep,
  array_intersect_key(
    $comment_meta['tests'],
    array(
      'x1' => NULL,
      'x2' => NULL,
      'x3' => NULL,
      'x4' => NULL,
      'x5' => NULL,
      'x6' => NULL,
      'x7' => NULL,
    )
  )
);