function testAdd()
  {
    $obj1 = new Object();
    $obj1->set('id', 1);

    $obj2 = new Object();
    $obj2->set('id', 2);

    $arr = array($obj1);
    $col = new ObjectCollection($arr);

    $col->add($obj2);

    $col->rewind();

    $this->assertEqual($col->current(), $obj1);

    $col->next();
    $this->assertEqual($col->current(), $obj2);

    $col->next();
    $this->assertFalse($col->valid());
  }
 function rewind()
 {
   $this->_ensureCollection();
   parent :: rewind();
 }