test_request_modification() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_composition.py lines 243–268

    def test_request_modification(self) -> None:
        """Test handlers modifying the request."""
        requests_seen = []

        def outer_add_context(
            request: ModelRequest, handler: Callable[[ModelRequest], ModelResponse]
        ) -> ModelResponse:
            modified_request = create_test_request(
                messages=[*request.messages], system_prompt="Added by outer"
            )
            return handler(modified_request)

        def inner_track_request(
            request: ModelRequest, handler: Callable[[ModelRequest], ModelResponse]
        ) -> ModelResponse:
            requests_seen.append(request.system_prompt)
            return handler(request)

        composed = _chain_model_call_handlers([outer_add_context, inner_track_request])
        assert composed is not None

        result = composed(create_test_request(), create_mock_base_handler(content="response"))

        assert requests_seen == ["Added by outer"]
        assert isinstance(result, _ComposedExtendedModelResponse)
        assert result.model_response.result[0].content == "response"