Getting old of OrganizationUser objects via their primary keys is a bit opaque. For example, just by looking at the code you wouldn't guess that self.harry actually refers to Andy Aardvark. It would be possible to say something like
```python
    def setUp(self):
    	self.countrycritters = Organization.objects.get(name="Country Critters")
        org_users = OrganizationUser.objects.filter(organization=self.countrycritters)
        self.harry = org_users.get(user__username="harry")
        self.betty = org_users.get(user__username="betty")
        self.charlie = org_users.get(user__username="charlie")
        self.debbie = org_users.get(user__username="debbie")
        self.zarathustra = org_users.get(user__username="zarathustra")
```
(except that the test would fail because Harry and Andy have different permissions)