def METHOD_NAME(self):
    collectingeventattribute = models.Collectingeventattribute.objects.create(
        discipline=self.discipline,
        hosttaxon=self.roottaxon)
    with self.assertRaises(ProtectedError):
        self.roottaxon.delete()
    collectingeventattribute.hosttaxon = None
    collectingeventattribute.save()
    self.roottaxon.delete()