`self.assert_entities_equal()` (defined in https://github.com/snarfed/webutil/blob/master/testutil.py) can help with this. i think you can simplify the rest of this method to:

```py
self.assert_entities_equal(
  [SyndicatedPost(original='http://author/post/permalink',
                  syndication='http://source/post/url'),
   SyndicatedPost(original='http://author/post/permalink',
                  syndication='http://anotherSource/statuses/postid')],
  SyndicatedPost.query())
```