Your test setup is ok like this. But please split this big assertion in to different test cases. When having an assertion here, its very hard to find or understand the bug/assertion. 

For example:
```
def first_item_is_a_repository_root(self):
 self.assertEquals('opengever.repository.repositoryroot', source[0].get(`_type`))

def empty_classification_is_dropped_out_of_the_source(self):
 self.assertEquals('MARKER', source[1].get(`classification`, 'MARKER'))
```