test_summarization_middleware_cutoff_at_boundary() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py lines 936–949

def test_summarization_middleware_cutoff_at_boundary() -> None:
    """Test cutoff index determination at exact message boundaries."""
    middleware = SummarizationMiddleware(
        model=MockChatModel(), trigger=("messages", 5), keep=("messages", 5)
    )

    # When we want to keep exactly as many messages as we have
    messages: list[AnyMessage] = [HumanMessage(content=str(i)) for i in range(5)]
    cutoff = middleware._find_safe_cutoff(messages, 5)
    assert cutoff == 0  # Should not cut anything

    # When we want to keep more messages than we have
    cutoff = middleware._find_safe_cutoff(messages, 10)
    assert cutoff == 0