Add async tests

[salomvary]

As discussed with @tim-schilling in #1828 a good start towards adding async support is adding tests involving async views and async ORM usage.

Unfortunately, none of the automated tests showcase the problem described in #1828 as there is no ASGI equivalent of LiveServerTestCase and the issue seems to be specific to running an actual ASGI server.

Therefore, despite all tests are green, async support is still not there. Running the example app with an ASGI server using ASYNC_SERVER=true python example/manage.py runserver and visiting http://127.0.0.1:8000/async/db-concurrent/ does exhibit the deadlock though.

See also #1819.

[tim-schilling]

Sorry for the late reply on this. Thank you for creating this PR!

I wonder if we could test this functionality by starting up runserver with the asgi application, then using a separate selenium test against that rather than using the Django test runner.

[tim-schilling]

Closing in favor of #1938. Thank you for pushing this forward @salomvary! Your work here was helpful to the GSoC project to push the toolbar forward with async compatibility.

[tim-schilling]

Nope, I was wrong. This still has value.

[tim-schilling]

Rebased on main

[tim-schilling]

@salomvary could you confirm that the deadlock issue is not a problem in this version? @salty-ivy removed the sql panel from async installations which seems to have resolved that issue. Granted, now the issue is that the toolbar doesn't have a SQL panel for async apps, but at least it doesn't lock up.

[tim-schilling]

Thank you @salomvary for this! I'd still like your confirmation the deadlock has been handled when/if you have time.

[salty-ivy]

@salomvary could you confirm that the deadlock issue is not a problem in this version? @salty-ivy removed the sql panel from async installations which seems to have resolved that issue. Granted, now the issue is that the toolbar doesn't have a SQL panel for async apps, but at least it doesn't lock up.

I think it was more of a django ORM issue rather than the toolbar itself. @salomvary mentioned it here
https://forum.djangoproject.com/t/are-concurrent-database-queries-in-asgi-a-thing/24136/2

[tim-schilling]

Weird, on my machine it was executing them concurrently (I think). Or at least they didn't result in a deadlock.

[salomvary]

Thank you @salomvary for this! I'd still like your confirmation the deadlock has been handled when/if you have time.

Yep, the deadlock was very likely not cause by the Debug Toolbar, it is a Django issue. As far as I can remember I was later able to reproduce the deadlock with Debug Toolbar not even installed.