function testCantDeleteNoNodeId()
  {
    $mapper = new SiteObjectMapper();
    $this->site_object->setReturnValue('getId', 10);

    try
    {
      $mapper->canDelete($this->site_object);
      $this->assertTrue(false);
    }
    catch(LimbException $e)
    {
      $this->assertEqual($e->getMessage(), 'node id not set');
    }
  }
 protected function _doParentDelete($site_object)
 {
   parent :: delete($site_object);
 }