Increasing test coverage for JsonAdapter

[Y-1huadb]

This PR adds three additional test cases for the JsonAdapter:

• Handling Different Input and Output Field Types: The test ensures that the JSONAdapter correctly processes various input and output field types, including nested Pydantic models and complex data structures. It verifies that the adapter handles both simple and nested fields in the expected manner when making requests to the model.
• Passing Signature Information to the Model: This test verifies that the request sent to the language model (LM) includes the correct signature information. It checks that the input and output fields, along with their descriptions and types, are correctly embedded in the request, ensuring the LM receives the signature as intended.
• Raising Explicit Errors on Failure: The test ensures that when parsing errors or mismatches between expected and actual field keys occur, the JSONAdapter raises a clear and explicit error. Specifically, if the model's output does not align with the expected fields defined in the signature, a ValueError is raised with an appropriate message. This helps prevent silent failures and provides clear feedback when something goes wrong during parsing.

All tests could be passed locally.

If there are any mistakes in my attempt, I sincerely apologize and appreciate you taking the time to review my pull request. I have great respect for your work. Thanks.

[Y-1huadb]

Fixes: #8121

[chenmoneygithub]

Thanks for the PR! left some comments to simplify the test

[chenmoneygithub]

Thanks for fixing! Overall LGTM, I will take over the cleanup and merge it. Thanks again for the conbribution!

[Y-1huadb]

I'm glad I could help. Thanks for handling the cleanup and merge!