test_empty_tools_list_is_valid() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_tools.py lines 215–244

def test_empty_tools_list_is_valid() -> None:
    """Test that middleware can set tools to an empty list."""

    @tool
    def some_tool(value: str) -> str:
        """Some tool."""
        return "result"

    class NoToolsMiddleware(AgentMiddleware):
        def wrap_model_call(
            self,
            request: ModelRequest,
            handler: Callable[[ModelRequest], ModelResponse],
        ) -> ModelCallResult:
            # Remove all tools
            request = request.override(tools=[])
            return handler(request)

    model = FakeToolCallingModel()

    agent = create_agent(
        model=model,
        tools=[some_tool],
        system_prompt="You are a helpful assistant.",
        middleware=[NoToolsMiddleware()],
    )

    # Should run without error even with no tools
    result = agent.invoke({"messages": [HumanMessage("Hello")]})
    assert "messages" in result