public function testValidObjectsForBaseFields()
 {
     $obj = new DataObjectTest_ValidatedObject();
     foreach (array('Created', 'LastEdited', 'ClassName', 'ID') as $field) {
         $helper = $obj->dbObject($field);
         $this->assertTrue($helper instanceof DBField, "for {$field} expected helper to be DBField, but was " . (is_object($helper) ? get_class($helper) : "null"));
     }
 }