test_dynamic_tools.py — langchain Source File

Source Code

"""Tests for dynamic tool registration via middleware.

These tests verify that middleware can dynamically register and handle tools
that are not declared upfront when creating the agent.
"""

import asyncio
from collections.abc import Awaitable, Callable
from typing import Any

import pytest
from langchain_core.messages import HumanMessage, ToolCall, ToolMessage
from langchain_core.tools import tool
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.types import Command

from langchain.agents.factory import create_agent
from langchain.agents.middleware.types import (
    AgentMiddleware,
    ModelCallResult,
    ModelRequest,
    ModelResponse,
    ToolCallRequest,
)
from tests.unit_tests.agents.model import FakeToolCallingModel


@tool
def static_tool(value: str) -> str:
    """A static tool that is always available."""
    return f"Static result: {value}"


@tool
def dynamic_tool(value: str) -> str:
    """A dynamically registered tool."""
    return f"Dynamic result: {value}"


@tool
def another_dynamic_tool(x: int, y: int) -> str:
    """Another dynamically registered tool for calculations."""
    return f"Sum: {x + y}"


# -----------------------------------------------------------------------------
# Middleware classes
# -----------------------------------------------------------------------------


class DynamicToolMiddleware(AgentMiddleware):
    """Middleware that dynamically adds and handles a tool (sync and async)."""

    def wrap_model_call(
        self,
        request: ModelRequest,
        handler: Callable[[ModelRequest], ModelResponse],
    ) -> ModelCallResult:
        updated = request.override(tools=[*request.tools, dynamic_tool])
        return handler(updated)
// ... (350 more lines)