/**
  * Test the sanitiseORderBy() method.
  */
 public function testSanitiseOrderBy()
 {
     $dao = new PostMySQLDAO();
     $order_by = "p.post_id";
     $order_by = $dao->sanitiseOrderBy($order_by);
     $this->assertEqual($order_by, "p.post_id");
     $order_by = "post_id";
     $order_by = $dao->sanitiseOrderBy($order_by);
     $this->assertEqual($order_by, "post_id");
     $order_by = "non-existent-table-name";
     $order_by = $dao->sanitiseOrderBy($order_by);
     $this->assertEqual($order_by, "pub_date");
     $order_by = "'; DROP TABLE tu_posts;--";
     $order_by = $dao->sanitiseOrderBy($order_by);
     $this->assertEqual($order_by, "pub_date");
 }