test_wrap_tool_call_inner_short_circuits() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_wrap_tool_call.py lines 618–675

def test_wrap_tool_call_inner_short_circuits() -> None:
    """Test composition when inner middleware short-circuits."""
    call_log = []

    @wrap_tool_call(name="OuterWrapper")
    def outer(
        request: ToolCallRequest, handler: Callable[[ToolCallRequest], ToolMessage | Command[Any]]
    ) -> ToolMessage | Command[Any]:
        call_log.append("outer_before")
        response = handler(request)
        call_log.append("outer_after")

        # Wrap inner's response
        if isinstance(response, ToolMessage):
            return ToolMessage(
                content=f"outer_wrapped: {response.content}",
                tool_call_id=response.tool_call_id,
                name=response.name,
            )
        return response

    @wrap_tool_call(name="InnerShortCircuit")
    def inner_short_circuit(
        request: ToolCallRequest, handler: Callable[[ToolCallRequest], ToolMessage | Command[Any]]
    ) -> ToolMessage | Command[Any]:
        call_log.append("inner_short_circuit")
        # Don't call handler, return custom response
        return ToolMessage(
            content="inner_result",
            tool_call_id=request.tool_call["id"],
            name=request.tool_call["name"],
        )

    model = FakeToolCallingModel(
        tool_calls=[
            [ToolCall(name="search", args={"query": "test"}, id="1")],
            [],
        ]
    )

    agent = create_agent(
        model=model,
        tools=[search],
        middleware=[outer, inner_short_circuit],
        checkpointer=InMemorySaver(),
    )

    result = agent.invoke(
        {"messages": [HumanMessage("Search")]},
        {"configurable": {"thread_id": "test"}},
    )

    # Verify order: outer_before -> inner short circuits -> outer_after
    assert call_log == ["outer_before", "inner_short_circuit", "outer_after"]

    tool_messages = [m for m in result["messages"] if isinstance(m, ToolMessage)]
    assert len(tool_messages) == 1
    assert "outer_wrapped: inner_result" in tool_messages[0].content