Feature Suggestion: Include a Reason When Constraints Cannot Be Applied

[Ennovate-com]

When the verifier agent is unable to apply a constraint filter, it would be helpful for the Problem Report to include a reason why it failed. For example, instead of:

Constraint specified for input_descriptor_123 does not apply to the enclosed credential in $.verifiableCredential[0]

... the message could include the reason that the constraint could not be applied, with the specific path or item that did not match. For example:

Constraint specified for input_descriptor_123 does not apply to the enclosed credential in $.verifiableCredential[0]
Reason: Credential is not applicable for field 11111111-2222-3333-4444-56789abcdef0 with paths ['$.credentialSubject.part1.part2']

This indicates that the field indicated in the message was not found in the Reveal Document or the full Credential.

or

Constraint specified for input_descriptor_123 does not apply to the enclosed credential in $.verifiableCredential[0]
Reason: No field in constraints for part2 under parent path "$.credentialSubject.part1"

This indicates that the "part2" property found in the Reveal Document under "$.credentialSubject.part1" was not found in the list of fields in the constraints.

[dbluhm]

I like this suggestion; however, the implementation is a little less "Pythonic" than it ought to be. First, the nitpicky comment: variables should be snake_case (failReason is what I'm referring to specifically). And second, I think the fail reasons should not be reported as a string from the constraint application method. The semantics are a bit too loose, IMO. I would recommend reporting the fail reason in an exception that is caught by the caller.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

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[dbluhm]

Thanks for the contribution and for the prompt turn around on feedback!

[Ennovate-com]

@dbluhm And, likewise, thanks for the quick feedback and merge. Much appreciated.