test_parallel_write_todos_with_other_tools() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_todo.py lines 567–623

def test_parallel_write_todos_with_other_tools() -> None:
    """Test that parallel write_todos calls are rejected but other tool calls remain."""
    middleware = TodoListMiddleware()

    # Create an AI message with two write_todos calls and one other tool call
    ai_message = AIMessage(
        content="I'll do multiple things",
        tool_calls=[
            {
                "name": "some_other_tool",
                "args": {"param": "value"},
                "id": "call_other",
                "type": "tool_call",
            },
            {
                "name": "write_todos",
                "args": {"todos": [{"content": "Task 1", "status": "pending"}]},
                "id": "call_1",
                "type": "tool_call",
            },
            {
                "name": "write_todos",
                "args": {"todos": [{"content": "Task 2", "status": "pending"}]},
                "id": "call_2",
                "type": "tool_call",
            },
        ],
    )

    state: PlanningState = {"messages": [HumanMessage(content="Hello"), ai_message]}

    # Call after_model hook
    result = middleware.after_model(state, _fake_runtime())

    # Should return error messages for write_todos calls only
    assert result == {
        "messages": [
            ToolMessage(
                content=(
                    "Error: The `write_todos` tool should never be called multiple times "
                    "in parallel. Please call it only once per model invocation to update "
                    "the todo list."
                ),
                tool_call_id="call_1",
                status="error",
            ),
            ToolMessage(
                content=(
                    "Error: The `write_todos` tool should never be called multiple times "
                    "in parallel. Please call it only once per model invocation to update "
                    "the todo list."
                ),
                tool_call_id="call_2",
                status="error",
            ),
        ]
    }