docs: Correct schema parsing for JSONField

[beruic]

This fixes #5873.

[carltongibson]

Hi @beruic. Can you add a regression test for this too please? Thanks.

[beruic]

Well, I would like to, but this is new ground for me, time is sparse, and i already spend a lot of time tracking this down. I have tested this informally, and now I have looked at how to write a test for this for about an hour, and I cannot figure out how to test this.

Perhaps there should just be made an issue to test rest_framework.schemas.inspectors.field_to_schema() by it self? This of course means that all the other fields should be tested, but then again, it feels kinda stupid to do. It really any value. I think it would be valuable if you could test the docs-generated HTML for each field, but that is still way beyond my scope of understanding of DRF.
Perhaps it would make sens to make it a part of some test of rest_framework.schemas.inspectors.AutoSchema, but again that is beyond my scope.

If it really is the case that none of the other output of rest_framework.schemas.inspectors.field_to_schema()is tested, I think this should just be merged, and an issue should be created to figure out how to test.
All in all I think this is a bigger task, but perhaps you are wiser @carltongibson?

[carltongibson]

The test coverage here is sub-optimal. All the schema related code is still quite new and so this is to be expected.

As we make changes we want to add coverage. We try not to add changes without a regression test to make sure future changes don't break anything.

A test on field_to_schema() will be fine. I'm happy for you just to test the JSONField case. We can add other cases as a separate clean-up later.

Thanks for the effort!

[beruic]

I have added tests now, testing JSONField and the simple cases of rest_framework.schemas.inspectors.field_to_schema(). The test is prepared for adding more cases easily, as long as you know what you are doing ;)

[carltongibson]

Yep. This looks good. Thanks @beruic.