test_todo.py — langchain Source File

Source Code

"""Unit tests for TodoListMiddleware."""

from __future__ import annotations

from typing import TYPE_CHECKING, Any, cast

import pytest
from langchain_core.language_models.fake_chat_models import GenericFakeChatModel
from langchain_core.messages import AIMessage, HumanMessage, ToolMessage

from langchain.agents.factory import create_agent
from langchain.agents.middleware.todo import (
    WRITE_TODOS_SYSTEM_PROMPT,
    WRITE_TODOS_TOOL_DESCRIPTION,
    PlanningState,
    TodoListMiddleware,
    write_todos,
)
from langchain.agents.middleware.types import AgentState, ModelRequest, ModelResponse
from tests.unit_tests.agents.model import FakeToolCallingModel

if TYPE_CHECKING:
    from langgraph.runtime import Runtime


def _fake_runtime() -> Runtime:
    return cast("Runtime", object())


def _make_request(system_prompt: str | None = None) -> ModelRequest:
    """Create a minimal ModelRequest for testing."""
    model = GenericFakeChatModel(messages=iter([AIMessage(content="response")]))
    return ModelRequest(
        model=model,
        system_prompt=system_prompt,
        messages=[],
        tool_choice=None,
        tools=[],
        response_format=None,
        state=AgentState(messages=[]),
        runtime=_fake_runtime(),
        model_settings={},
    )


# ==============================================================================
# Synchronous Tests
# ==============================================================================


def test_todo_middleware_initialization() -> None:
    """Test that TodoListMiddleware initializes correctly."""
    middleware = TodoListMiddleware()
    assert middleware.state_schema == PlanningState
    assert len(middleware.tools) == 1
    assert middleware.tools[0].name == "write_todos"


def test_has_write_todos_tool() -> None:
    """Test that middleware registers the write_todos tool."""
// ... (748 more lines)