test_human_in_the_loop_middleware_description_as_callable() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_human_in_the_loop.py lines 539–593

def test_human_in_the_loop_middleware_description_as_callable() -> None:
    """Test that description field accepts both string and callable."""

    def custom_description(
        tool_call: ToolCall, state: AgentState[Any], runtime: Runtime[None]
    ) -> str:
        """Generate a custom description."""
        return f"Custom: {tool_call['name']} with args {tool_call['args']}"

    middleware = HumanInTheLoopMiddleware(
        interrupt_on={
            "tool_with_callable": InterruptOnConfig(
                allowed_decisions=["approve"],
                description=custom_description,
            ),
            "tool_with_string": InterruptOnConfig(
                allowed_decisions=["approve"],
                description="Static description",
            ),
        }
    )

    ai_message = AIMessage(
        content="I'll help you",
        tool_calls=[
            {"name": "tool_with_callable", "args": {"x": 1}, "id": "1"},
            {"name": "tool_with_string", "args": {"y": 2}, "id": "2"},
        ],
    )
    state = AgentState[Any](messages=[HumanMessage(content="Hello"), ai_message])

    captured_request = None

    def mock_capture_requests(request: Any) -> dict[str, Any]:
        nonlocal captured_request
        captured_request = request
        return {"decisions": [{"type": "approve"}, {"type": "approve"}]}

    with patch(
        "langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_capture_requests
    ):
        middleware.after_model(state, Runtime())

        assert captured_request is not None
        assert "action_requests" in captured_request
        assert len(captured_request["action_requests"]) == 2

        # Check callable description
        assert (
            captured_request["action_requests"][0]["description"]
            == "Custom: tool_with_callable with args {'x': 1}"
        )

        # Check string description
        assert captured_request["action_requests"][1]["description"] == "Static description"