Hmm, i think this is because of the permission check when quering the catalog the default way:
```
    brains = catalog(query)
```
But i think it would be wise to adjust the testing helper `obj2brain`, so that it makes an unrestricted query:
 ```
    brains = catalog.unrestrictedSearchResults(query)
```
Because in tests we usually don't want to check the permission stuff on a brain.

@lukasgraf what do you think?