protected function _requireVisitorWithTwoProducts()
{
$visitor = new Mage_Log_Model_Visitor();
$visitor->setSessionId(md5(time()) . md5(microtime()))->setLastVisitAt(now())->save();
$item = new Mage_Catalog_Model_Product_Compare_Item();
$item->setVisitorId($visitor->getId())->setProductId(1)->save();
$item = new Mage_Catalog_Model_Product_Compare_Item();
$item->setVisitorId($visitor->getId())->setProductId(2)->save();
Mage::getSingleton('Mage_Log_Model_Visitor')->load($visitor->getId());
$this->_assertCompareListEquals(array(1, 2));
}