Missing test coverage for FORWARD_PROPERTIES entries

[Clifford Gama]

possibly also with REVERSE_PROPERTIES

With the exception of _forward_fields_map you can remove entries of field-related properties from FORWARD_PROPERTIES and see no test failures. Discovered during #36207 ​review

[Jacob Walls]

I think this is worth covering, because at a glance it seems like a bug that db_returning_fields is omitted from the entries. A test would help clarify.

[Senthil Kumar]

I'm new and would like to take this on. May I assign it to myself? Assuming it's not time-sensitive, I’ll aim to add the test cases over the next few days.

[Jacob Walls]

Thanks for volunteering. There's some discussion in the linked PR review with Clifford's initial investigation, if that helps any.

[Senthil Kumar]

Thanks Jacob. I will be creating a PR soon.

[Senthil Kumar]

Based on your suggestion, I’ve revised the tests to ensure that the correct caches are expired. As you mentioned above, I’ve also added a failing test for db_returning_fields.

I have a question: now that we have a failing test, should I go ahead and add db_returning_fields under FORWARD_PROPERTIES, or should I leave the test as-is and mark it as expected to fail? I’d appreciate your guidance on this.

[Jacob Walls]

I left a note that it looks like additional properties besides db_returning_fields are worth clearing from the cache. Assuming we go with a subTest-style test instead of writing separate cases for each, I think fixing the behavior and testing in one commit would be simplest.

[Senthil Kumar]

Thanks for the patience again. I have revised the unit tests based on the suggested flow.
I have created a new PR as the previous PR's commit history got messed up. I have also fixed the behaviour and all the tests are passing now.

Link to the new PR: ​https://github.com/django/django/pull/19645

Previous PR: ​https://github.com/django/django/pull/19484

I have also dropped a quick question about using apps.clear_cache() in the PR. Hope to get some clarification on that. Thanks

[Jacob Walls <jacobtylerwalls@…>]

In 5ee651f:

Fixed #36369 -- Cleared additional cached properties in apps.clear_cache().

Thanks Clifford Gama for the report.

Co-authored-by: Jacob Walls <jacobtylerwalls@…>