test_structured_response_preserved() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_wrap_model_call_state_update.py lines 610–636

    def test_structured_response_preserved(self) -> None:
        """ExtendedModelResponse preserves structured_response from ModelResponse."""

        class StructuredMiddleware(AgentMiddleware):
            def wrap_model_call(
                self,
                request: ModelRequest,
                handler: Callable[[ModelRequest], ModelResponse],
            ) -> ExtendedModelResponse:
                response = handler(request)
                response_with_structured = ModelResponse(
                    result=response.result,
                    structured_response={"key": "value"},
                )
                return ExtendedModelResponse(
                    model_response=response_with_structured,
                )

        model = GenericFakeChatModel(messages=iter([AIMessage(content="Hello")]))
        agent = create_agent(model=model, middleware=[StructuredMiddleware()])

        result = agent.invoke({"messages": [HumanMessage("Hi")]})

        assert result.get("structured_response") == {"key": "value"}
        messages = result["messages"]
        assert len(messages) == 2
        assert messages[1].content == "Hello"