django-testing: mock datetime.datetime.now()

tests.py

import mock
from django.test import TestCase, Client

import datetime
class StubDate(datetime.datetime):
    pass

class TestApp(TestCase):

    @mock.patch('app.views.datetime.datetime', StubDate) #app is the $django_application_name
    def test_now(self):
        from datetime import datetime
        StubDate.now = classmethod(lambda cls: datetime(2015, 03, 11, 00, 16, 31, 99))

        response = self.client.get('/holiday/')
        self.assertEqual(response.status_code, 200)
        print response.content
        self.assertContains(response, '2015-03-11 00:16:31.000099')

views.py

import datetime
from django.http import HttpResponse

def now():
    return datetime.datetime.now()

def index(request):
    return HttpResponse(now())

This wouldn't even work - did you try it? mock.patch passes an extra parameter to the test method being decorated, which is the mock object itself - so test_now needs to take two parameters.

Aside from that, the approach is still not right. The only thing you need to to patch is views.now(), so that it returns the value you want. There's no need for the StubDate class at all.

The whole thing can just be:

class TestApp(TestCase):
    @mock.patch('app.views.now', return_value=datetime.datetime(2015, 3, 11, 0, 16, 31, 99))
    def test_now(self):
        response = self.client.get('/holiday/')
        self.assertContains(response, '2015-03-11 00:16:31.000099')

My test code worked. OK, let me try to update it based on your feedback.