django: mock post_save signal handler?

Question

tests.py

from unittest.mock import patch

from orders.models import Order

class OrderModelTest(CartSetupTestCase):

    def test_string_representation(self):
        # Mocking Order's post_save signal
        with patch('orders.signals.post_save_order', autospec=True) as mocked_handler:
            post_save.connect(
                mocked_handler,
                sender=Order,
                dispatch_uid='test_cache_mocked_handler'
            )
            order = Order.objects.create(
                user=self.user,
                merchant_uid="1475633246629",
                customer_name="asd",
                address="주소",
                address_detail="asdfdsa",
                postal_code="12345",
                phone_number="01095104344",
                possible_date_start="2011-11-24",
                possible_date_end="2011-11-24",
                possible_time_start="11:22 AM",
                possible_time_end="11:22 AM",
                total_price=self.cart.total_price,
            )

signals.py

@receiver(post_save, sender=Order, dispatch_uid="spacegraphy")
def post_save_order(sender, instance, created, **kwargs):
    if created:
        SlackNotification.objects.create(
            receiver="order_web",
            content="asdfasdf"
        )

I followed https://stackoverflow.com/a/13119150/3595632, but it doesn't work, which means, it called signal handler in real! (I checked it out using print())

Anything wrong?

Why not just call the function with your test? To test that the signal fires when something is created is a bit much considering it is core django. You can call the `signal.send` method with the appropriate signature as well. — theWanderer4865, Nov 07 '16 at 15:24
@theWanderer4865 I didn't catch what you said. Could you give me a example, please? — user3595632, Nov 07 '16 at 22:40
did you assert that the mock_handler was called? When your signal code is imported (when Django starts up) it will register any number of handlers to the signal - you should explicitly disconnect the other handler if you don't want it to run. There's more to be said but that would be step 1. — theWanderer4865, Nov 08 '16 at 15:10

score 2 · Answer 1 · answered Nov 07 '17 at 10:28

FWIW I followed the same, but needed to mock celery's send_task. After reading through, I did recognize, that signals are valuable and shouldn't be mocked (it's a desired action to fire them, right?), so the solution was to mock what was going on inside the signal (communication with external services). All in all I would suggest:

from unittest.mock import patch
from orders.models import Order

class OrderModelTest(CartSetupTestCase):

    @patch('orders.signals.SlackNotification.objects.create')
    def test_string_representation(self, create):
        order = Order.objects.create(
            user=self.user,
            merchant_uid="1475633246629",
            customer_name="asd",
            address="주소",
            address_detail="asdfdsa",
            postal_code="12345",
            phone_number="01095104344",
            possible_date_start="2011-11-24",
            possible_date_end="2011-11-24",
            possible_time_start="11:22 AM",
            possible_time_end="11:22 AM",
            total_price=self.cart.total_price,
        )
        self.assertEquals(1, create.call_count)

django: mock post_save signal handler?

1 Answers1