test_summarization_middleware_cutoff_at_start_of_tool_sequence() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py lines 1092–1110

def test_summarization_middleware_cutoff_at_start_of_tool_sequence() -> None:
    """Test cutoff when target lands exactly at the first ToolMessage."""
    middleware = SummarizationMiddleware(
        model=MockChatModel(), trigger=("messages", 8), keep=("messages", 4)
    )

    messages: list[AnyMessage] = [
        HumanMessage(content="msg1"),
        HumanMessage(content="msg2"),
        AIMessage(content="ai", tool_calls=[{"name": "tool", "args": {}, "id": "call1"}]),
        ToolMessage(content="result", tool_call_id="call1"),
        HumanMessage(content="msg3"),
        HumanMessage(content="msg4"),
    ]

    # Target cutoff index is len(messages) - messages_to_keep = 6 - 4 = 2
    # Index 2 is an AIMessage (safe cutoff point), so no adjustment needed
    cutoff = middleware._find_safe_cutoff(messages, messages_to_keep=4)
    assert cutoff == 2