Make ChannelsLiveServerTestCase compatible with Django 5.2 (#2148)

[dee077]

Description

In Django 5.2, the _pre_setup method of SimpleTestCase (and consequently TransactionTestCase) has been changed to a classmethod.
See in references in Django 5.2 and Django 5.1

I’ve implemented a minimal, Django version based change without disrupting its existing architecture.
Let me know if you require a different design solution.

To test this, you have to create a test sample app. Should I add a minimal app in this PR as well?

Closes #2148

Special Thanks

This work was completed as part of OpenWISP's contribution to Google Summer of Code 2025.
Thanks to both organizations for their support!

[pandafy]

From the point of maintenance and avoiding repetitive code, can we do this instead?

class ChannelsLiveServerTestCase(TransactionTestCase):
    # original definition (unchanged)

if VERSION >= (5, 2):
    ChannelsLiveServerTestCase._pre_setup = classmethod(ChannelsLiveServerTestCase._pre_setup)

I found that the QuerySet.as_manager uses similar definition, albeit for different reasons
https://github.com/django/django/blob/8c279113864c31cef539c6384a683e6ed832adca/django/db/models/query.py#L311-L320

Let's also add a comment explaining that this is required because of changes in Django 5.2 and add a TODO to remove this workaround while dropping support for older Django version (<5.2).

[nemesifier]

To test this, you have to create a test sample app. Should I add a minimal app in this PR as well?

I think we should do this. What do you think @pandafy?

[pandafy]

To test this, you have to create a test sample app. Should I add a minimal app in this PR as well?

Yes, please add a small Django project here which can be used to test the ChannelsLiveServerTestCase class.

[dee077]

How to proceed?

Hey @carltongibson, I am thinking of creating a sample real-time counter app using Django and Channels.

I am thinking of adding a live counter app using django which will have an input field on sending some text message which will broadcast live to all connected clients and appears in the list below with a count of total messages and show the text message instantly in real time in the django admin and create selenium tests for this using the ChannelsLiveServerTestCase.

Before proceeding further, I’d love to get your thoughts. Do you think this example is a good fit, or would you recommend a different solution?

[carltongibson]

@dee077 That sounds like a good example yes. It exercises the basics but is not too complex.

[dee077]

Updates

• Added sample project as described above.
• Add more settings to run the sample project in conftest.py
• Added selenium tests for the sample project using ChannelsLiveServerTestCase
• Make every test use @pytest.mark.django_db(transaction=True).
  Without transaction=True, some tests were conflicting with the WebSocket connection while running the Chrome WebDriver instance, causing below errors and failing the test suite.

scripts.js:12 WebSocket connection to 'ws://localhost:46483/ws/message/' 
failed: Error during WebSocket handshake: net::ERR_CONNECTION_RESET

• Added selenium in setup.cfg in test dependencies
• Added chromedriver in ci

Let me know if any updates are required.