So I have various signals and handlers which are sent across apps. However, when I perform tests / go into 'testing mode', I want these handlers to be disabled.
Is there a Django-specific way of disabling signals/handlers when in testing mode? I can think of a very simple way (of including the handlers within an if TESTING clause) but I was wondering if there was a better way built into Django?...
No, there is not. You can easily make a conditional connection though:
import sys
if not 'test' in sys.argv:
signal.connect(listener, sender=FooModel)
I found this question when looking to disable a signal for a set of test cases and Germano's answer lead me to the solution but it takes the opposite approach so I thought I'd add it.
In your test class:
class MyTest(TestCase):
def setUp(self):
# do some setup
signal.disconnect(listener, sender=FooModel)
Instead of adding decision code to adding the signal I instead disabled it at the point of testing which feels like a nicer solution to me (as the tests should be written around the code rather than the code around the tests). Hopefully is useful to someone in the same boat!
Edit: Since writing this I've been introduced to another way of disabling signals for testing. This requires the factory_boy package (v2.4.0+) which is very useful for simplifying tests in Django. You're spoilt for choice really:
import factory
from django.db.models import signals
class MyTest(TestCase):
@factory.django.mute_signals(signals.pre_save, signals.post_save)
def test_something(self):
Caveat thanks to ups: it mutes signals inside factory and when an object is created, but not further inside test when you want to make explicit save() - signal will be unmuted there. If this is an issue then using the simple disconnect in setUp is probably the way to go.
Here's a full example with imports on how to disable a specific signal in a test, if you don't want to use FactoryBoy.
from django.db.models import signals
from myapp.models import MyModel
class MyTest(TestCase):
def test_no_signal(self):
signals.post_save.disconnect(sender=MyModel, dispatch_uid="my_id")
... after this point, the signal is disabled ...
This should be matched against your receiver, this example would match this receiver:
@receiver(post_save, sender=MyModel, dispatch_uid="my_id")
I tried to disable the signal without specifying the dispatch_uid and it didn't work.
I had a similar issue and wasn't able to successfully disconnect my signal using signals.post_save.disconnect(). Found this alternative approach that creates a decorator to override the SUSPEND_SIGNALS setting on specified tests and signals. Might be useful for anyone in the same boat.
First, create the decorator:
import functools
from django.conf import settings
from django.dispatch import receiver
def suspendingreceiver(signal, **decorator_kwargs):
def our_wrapper(func):
@receiver(signal, **decorator_kwargs)
@functools.wraps(func)
def fake_receiver(sender, **kwargs):
if settings.SUSPEND_SIGNALS:
return
return func(sender, **kwargs)
return fake_receiver
return our_wrapper
Replace the usual @receiver decorator on your signal with the new one:
@suspendingreceiver(post_save, sender=MyModel)
def mymodel_post_save(sender, **kwargs):
work()
Use Django's override_settings() on your TestCase:
@override_settings(SUSPEND_SIGNALS=True)
class MyTestCase(TestCase):
def test_method(self):
Model.objects.create() # post_save_receiver won't execute
Thanks to Josh Smeaton, who wrote the blog.
If you connect receivers to signals in AppConfig.ready, which is recommended by documentation, see https://docs.djangoproject.com/en/2.2/topics/signals/#connecting-receiver-functions, you can create an alternative AppConfig for your tests with other signal receivers.
