/**
  * save shared persistent filter
  * 
  * @return Tinebase_Model_PersistentFilter
  */
 public function testSaveSharedFavorite()
 {
     $filter = new Tinebase_Model_PersistentFilter(Tinebase_Frontend_Json_PersistentFilterTest::getPersistentFilterData());
     $filter->account_id = null;
     $newFilter = $this->_instance->create($filter);
     $this->assertTrue(count($newFilter->grants) === 2, 'did not find default grants in filter: ' . print_r($newFilter->toArray(), true));
     return $newFilter;
 }