Getting $ref history

[atsuoishimoto]

In large schemas, understanding which $ref is being referenced when an error occurs can be helpful in debugging. We used to refer to the history of $ref with (ill-mannered) code like this:

for error in validator.iter_errors(instance):
    print(validator.resolver._scopes_stack)
    print(error)

However, with the current version of jsonschema, validator.resolver is deprecated, and it will be not possible to refer to it.

Is there a legitimate way to retrieve this information in jsonschema?

Reference: #1144

[Julian]

(Bringing over a comment here for us to think about):

Doing this is likely required to support #1008 regardless, because in the standard output formats, $refs actually are preserved in error paths in a few places.

But to do this correctly we'd also need to handle preserving $dynamicRef and $recursiveRef references, so some extra thought is needed.

On the bright side the objects used within the referencing library were written partially to support this (referencing's Resolver.dynamic_scope essentially contains this information).

Thanks for filing the issue (and ideas welcome from anyone thinking about this).