/**
  * test remove all grants (should not be possible)
  */
 public function testAddGrants()
 {
     $defaultUserGroup = Tinebase_Group::getInstance()->getDefaultGroup();
     $filter = $this->testSaveSharedFavorite();
     $filter->grants->addRecord(new Tinebase_Model_PersistentFilterGrant(array('account_id' => $defaultUserGroup->getId(), 'account_type' => Tinebase_Acl_Rights::ACCOUNT_TYPE_GROUP, 'record_id' => $filter->getId(), Tinebase_Model_Grants::GRANT_READ => true)));
     $updatedFilter = $this->_instance->update($filter);
     $this->assertEquals(3, count($updatedFilter->grants));
     $grant = $updatedFilter->grants->filter('account_id', $defaultUserGroup->getId())->getFirstRecord();
     $this->assertTrue($grant !== null);
     $this->assertTrue($grant->userHasGrant(Tinebase_Model_PersistentFilterGrant::GRANT_READ));
 }