test_inference_to_tool_output() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/test_response_format_integration.py lines 112–143

def test_inference_to_tool_output(*, use_responses_api: bool) -> None:
    """Test that tool output is inferred when a model supports it."""
    model_kwargs: dict[str, Any] = {"model": "gpt-5", "use_responses_api": use_responses_api}

    if "OPENAI_API_KEY" not in os.environ:
        model_kwargs["api_key"] = "foo"

    model = ChatOpenAI(**model_kwargs)

    agent = create_agent(
        model,
        system_prompt=(
            "You are a helpful weather assistant. Please call the get_weather tool "
            "once, then use the WeatherReport tool to generate the final response."
        ),
        tools=[get_weather],
        response_format=ToolStrategy(WeatherBaseModel),
    )
    response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

    assert isinstance(response["structured_response"], WeatherBaseModel)
    assert response["structured_response"].temperature == 75.0
    assert response["structured_response"].condition.lower() == "sunny"
    assert len(response["messages"]) == 5

    assert [m.type for m in response["messages"]] == [
        "human",  # "What's the weather?"
        "ai",  # "What's the weather?"
        "tool",  # "The weather is sunny and 75°F."
        "ai",  # structured response
        "tool",  # artificial tool message
    ]