test_tool_runtime_state_access() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/test_injected_runtime_create_agent.py lines 123–150

def test_tool_runtime_state_access() -> None:
    """Test that tools can access and use state via ToolRuntime."""

    @tool
    def state_aware_tool(query: str, runtime: ToolRuntime) -> str:
        """Tool that uses state to provide context-aware responses."""
        messages = runtime.state.get("messages", [])
        msg_count = len(messages)
        return f"Query: {query}, Message count: {msg_count}"

    agent = create_agent(
        model=FakeToolCallingModel(
            tool_calls=[
                [{"args": {"query": "test"}, "id": "state_call", "name": "state_aware_tool"}],
                [],
            ]
        ),
        tools=[state_aware_tool],
        system_prompt="You are a helpful assistant.",
    )

    result = agent.invoke({"messages": [HumanMessage("Hello"), HumanMessage("World")]})

    # Check that tool accessed state correctly
    tool_message = result["messages"][3]
    assert isinstance(tool_message, ToolMessage)
    # Should have original 2 HumanMessages + 1 AIMessage before tool execution
    assert "Message count: 3" in tool_message.content