class ViewSet(viewsets.ModelViewSet):
    queryset = Test.objects.all()
    serializers = {
        'default': DefaultSerializer,
        ‘list’: ListSerializer,
        ‘create’: CreateSerializer
    }

    def get_serializer_class(self):
        return self.serializers.get(self.action, self.serializers['default'])

def voteYes(self): 
    Poll.objects.filter(pk=self.pk).update(agree=models.F('agree') + 1)

def test_voteYes(self):
    current_agree = self.models.agree
    self.models.voteYes()
    new_agree = current_agree + 1
    self.assertEquals(self.models.agree, new_agree)