nanobot/tests/agent/test_mcp_connection.py

"""Tests for MCP connection lifecycle in AgentLoop."""

from __future__ import annotations

import asyncio
from contextlib import AsyncExitStack
from typing import Any
from unittest.mock import MagicMock

import pytest

from nanobot.agent.loop import AgentLoop
from nanobot.agent.tools import mcp as mcp_runtime
from nanobot.agent.tools.base import Tool
from nanobot.bus.queue import MessageBus
from nanobot.config.loader import load_config, save_config
from nanobot.config.schema import MCPServerConfig


class _FakeMcpTool(Tool):
    def __init__(self, name: str) -> None:
        self._name = name

    @property
    def name(self) -> str:
        return self._name

    @property
    def description(self) -> str:
        return "fake MCP tool"

    @property
    def parameters(self) -> dict[str, Any]:
        return {"type": "object", "properties": {}}

    async def execute(self, **_kwargs: Any) -> str:
        return "ok"


def _make_loop(tmp_path, *, mcp_servers: dict | None = None) -> AgentLoop:
    bus = MessageBus()
    provider = MagicMock()
    provider.get_default_model.return_value = "test-model"
    provider.generation.max_tokens = 4096
    return AgentLoop(
        bus=bus,
        provider=provider,
        workspace=tmp_path,
        model="test-model",
        mcp_servers=mcp_servers or {"test": object()},
    )


@pytest.mark.asyncio
async def test_connect_mcp_retries_when_no_servers_connect(tmp_path, monkeypatch: pytest.MonkeyPatch):
    loop = _make_loop(tmp_path)
    attempts = 0

    async def _fake_connect(_servers, _registry):
        nonlocal attempts
        attempts += 1
        return {}

    monkeypatch.setattr("nanobot.agent.tools.mcp.connect_mcp_servers", _fake_connect)

    await loop._connect_mcp()
    await loop._connect_mcp()

    assert attempts == 2
    assert loop._mcp_connected is False
    assert loop._mcp_stacks == {}


@pytest.mark.asyncio
async def test_reload_mcp_servers_adds_and_removes_tools_without_restart(
    tmp_path,
    monkeypatch: pytest.MonkeyPatch,
):
    config_path = tmp_path / "config.json"
    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
    config = load_config()
    config.tools.mcp_servers["browserbase"] = MCPServerConfig(
        type="stdio",
        command="browserbase-mcp",
    )
    save_config(config)

    closed: list[str] = []

    async def _mark_closed(name: str) -> None:
        closed.append(name)

    async def _fake_connect(servers, registry):
        stacks = {}
        for name in servers:
            registry.register(_FakeMcpTool(f"mcp_{name}_navigate"))
            stack = AsyncExitStack()
            await stack.__aenter__()
            stack.push_async_callback(_mark_closed, name)
            stacks[name] = stack
        return stacks

    monkeypatch.setattr("nanobot.agent.tools.mcp.connect_mcp_servers", _fake_connect)
    loop = _make_loop(tmp_path, mcp_servers={})

    added = await mcp_runtime.reload_servers(loop, loop.tools)

    assert added["ok"] is True
    assert added["added"] == ["browserbase"]
    assert loop.tools.has("mcp_browserbase_navigate")
    assert "browserbase" in loop._mcp_stacks

    config = load_config()
    del config.tools.mcp_servers["browserbase"]
    save_config(config)

    removed = await mcp_runtime.reload_servers(loop, loop.tools)

    assert removed["ok"] is True
    assert removed["removed"] == ["browserbase"]
    assert not loop.tools.has("mcp_browserbase_navigate")
    assert "browserbase" not in loop._mcp_stacks
    assert closed == ["browserbase"]


@pytest.mark.asyncio
async def test_request_mcp_reload_reaches_runtime_control_without_restart(
    tmp_path,
    monkeypatch: pytest.MonkeyPatch,
):
    config_path = tmp_path / "config.json"
    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
    config = load_config()
    config.tools.mcp_servers["browserbase"] = MCPServerConfig(
        type="stdio",
        command="browserbase-mcp",
    )
    save_config(config)

    closed: list[str] = []

    async def _mark_closed(name: str) -> None:
        closed.append(name)

    async def _fake_connect(servers, registry):
        stacks = {}
        for name in servers:
            registry.register(_FakeMcpTool(f"mcp_{name}_navigate"))
            stack = AsyncExitStack()
            await stack.__aenter__()
            stack.push_async_callback(_mark_closed, name)
            stacks[name] = stack
        return stacks

    monkeypatch.setattr("nanobot.agent.tools.mcp.connect_mcp_servers", _fake_connect)
    loop = _make_loop(tmp_path, mcp_servers={})

    async def _handle_one_runtime_control() -> None:
        msg = await loop.bus.consume_inbound()
        handled = await mcp_runtime.handle_runtime_control(loop, msg, loop.tools)
        assert handled is True

    consumer = asyncio.create_task(_handle_one_runtime_control())
    result = await mcp_runtime.request_mcp_reload(loop.bus, timeout=2.0)
    await consumer

    assert result["ok"] is True
    assert result["added"] == ["browserbase"]
    assert result["requires_restart"] is False
    assert loop.tools.has("mcp_browserbase_navigate")

    config = load_config()
    del config.tools.mcp_servers["browserbase"]
    save_config(config)

    consumer = asyncio.create_task(_handle_one_runtime_control())
    result = await mcp_runtime.request_mcp_reload(loop.bus, timeout=2.0)
    await consumer

    assert result["ok"] is True
    assert result["removed"] == ["browserbase"]
    assert result["requires_restart"] is False
    assert not loop.tools.has("mcp_browserbase_navigate")
    assert closed == ["browserbase"]


@pytest.mark.asyncio
async def test_reload_mcp_servers_retries_configured_server_without_live_stack(
    tmp_path,
    monkeypatch: pytest.MonkeyPatch,
):
    config_path = tmp_path / "config.json"
    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
    config = load_config()
    config.tools.mcp_servers["browserbase"] = MCPServerConfig(
        type="stdio",
        command="browserbase-mcp",
    )
    save_config(config)

    async def _fake_connect(servers, registry):
        stacks = {}
        for name in servers:
            registry.register(_FakeMcpTool(f"mcp_{name}_navigate"))
            stack = AsyncExitStack()
            await stack.__aenter__()
            stacks[name] = stack
        return stacks

    monkeypatch.setattr("nanobot.agent.tools.mcp.connect_mcp_servers", _fake_connect)
    loop = _make_loop(tmp_path, mcp_servers={"browserbase": config.tools.mcp_servers["browserbase"]})

    result = await mcp_runtime.reload_servers(loop, loop.tools)

    assert result["ok"] is True
    assert result["added"] == []
    assert result["changed"] == []
    assert result["retried"] == ["browserbase"]
    assert loop.tools.has("mcp_browserbase_navigate")
    await loop.close_mcp()