OpenHands/tests/unit/test_mcp_tool_timeout_stall.py
Rohit Malhotra 25d9cf2890
[Refactor]: Add LLMRegistry for llm services (#9589)
Co-authored-by: openhands <openhands@all-hands.dev>
Co-authored-by: Graham Neubig <neubig@gmail.com>
Co-authored-by: Engel Nyst <enyst@users.noreply.github.com>
2025-08-18 02:11:20 -04:00

267 lines
8.4 KiB
Python

"""Test for MCP tool timeout causing agent to stall indefinitely."""
import asyncio
import json
from unittest import mock
import pytest
from mcp import McpError
from openhands.controller.agent import Agent
from openhands.controller.agent_controller import AgentController
from openhands.core.schema import AgentState
from openhands.events.action.mcp import MCPAction
from openhands.events.action.message import SystemMessageAction
from openhands.events.event import EventSource
from openhands.events.observation.mcp import MCPObservation
from openhands.events.stream import EventStream
from openhands.mcp.client import MCPClient
from openhands.mcp.tool import MCPClientTool
from openhands.mcp.utils import call_tool_mcp
from openhands.server.services.conversation_stats import ConversationStats
from openhands.storage.memory import InMemoryFileStore
class MockConfig:
"""Mock config for testing."""
def __init__(self):
self.max_message_chars = 10000
class MockLLM:
"""Mock LLM for testing."""
def __init__(self):
self.metrics = None
self.config = MockConfig()
@pytest.fixture
def convo_stats():
return ConversationStats(None, 'convo-id', None)
class MockAgent(Agent):
"""Mock agent for testing."""
def __init__(self):
self.step_called = False
self.next_action = None
self.llm = MockLLM()
def step(self, *args, **kwargs):
"""Mock step method."""
self.step_called = True
return self.next_action
def get_system_message(self):
"""Mock get_system_message method."""
return SystemMessageAction(content='System message')
@pytest.mark.asyncio
async def test_mcp_tool_timeout_error_handling(convo_stats):
"""Test that verifies MCP tool timeout errors are properly handled and returned as observations."""
# Create a mock MCPClient
mock_client = mock.MagicMock(spec=MCPClient)
# Configure the mock to raise a McpError when call_tool is called
async def mock_call_tool(*args, **kwargs):
# Simulate a timeout
await asyncio.sleep(0.1)
# Create a mock error object with the message attribute
error = mock.MagicMock()
error.message = 'Timed out while waiting for response to ClientRequest. Waited 30.0 seconds.'
raise McpError(error)
mock_client.call_tool.side_effect = mock_call_tool
# Create a mock tool
mock_tool = MCPClientTool(
name='test_tool',
description='Test tool',
inputSchema={'type': 'object', 'properties': {}},
session=None,
)
mock_client.tools = [mock_tool]
mock_client.tool_map = {'test_tool': mock_tool}
# Create a mock file store
mock_file_store = InMemoryFileStore({})
# Create a mock event stream
event_stream = EventStream(sid='test-session', file_store=mock_file_store)
# Create a mock agent
agent = MockAgent()
# Create a mock agent controller
controller = AgentController(
agent=agent,
event_stream=event_stream,
convo_stats=convo_stats,
iteration_delta=10,
budget_per_task_delta=None,
sid='test-session',
)
# Set up the agent state
await controller.set_agent_state_to(AgentState.RUNNING)
# Create an MCP action
mcp_action = MCPAction(
name='test_tool',
arguments={'param': 'value'},
thought='Testing MCP timeout handling',
)
# Add the action to the event stream
event_stream.add_event(mcp_action, EventSource.AGENT)
# Set the pending action
controller._pending_action = mcp_action
# Before the fix, this would raise an exception and not return an observation
# Now with the fix, it should return an error observation
result = await call_tool_mcp([mock_client], mcp_action)
# Verify that the function returns an error observation
assert isinstance(result, MCPObservation)
content = json.loads(result.content)
assert content['isError'] is True
assert 'timed out' in content['error'].lower()
# The agent controller would now be able to continue processing
# because it received an error observation instead of an exception
# Verify that the agent is still in the RUNNING state
assert controller.get_agent_state() == AgentState.RUNNING
# Verify that the agent can continue processing
agent.next_action = MCPAction(
name='another_tool',
arguments={'param': 'value'},
thought='Another action after timeout',
)
# The agent controller would be able to step because it received an observation
# This demonstrates that the fix is working
@pytest.mark.asyncio
async def test_mcp_tool_timeout_agent_continuation(convo_stats):
"""Test that verifies the agent can continue processing after an MCP tool timeout."""
# Create a mock MCPClient
mock_client = mock.MagicMock(spec=MCPClient)
# Configure the mock to raise a McpError when call_tool is called
async def mock_call_tool(*args, **kwargs):
# Simulate a timeout
await asyncio.sleep(0.1)
# Create a mock error object with the message attribute
error = mock.MagicMock()
error.message = 'Timed out while waiting for response to ClientRequest. Waited 30.0 seconds.'
raise McpError(error)
mock_client.call_tool.side_effect = mock_call_tool
# Create a mock tool
mock_tool = MCPClientTool(
name='test_tool',
description='Test tool',
inputSchema={'type': 'object', 'properties': {}},
session=None,
)
mock_client.tools = [mock_tool]
mock_client.tool_map = {'test_tool': mock_tool}
# Create a mock file store
mock_file_store = InMemoryFileStore({})
# Create a mock event stream
event_stream = EventStream(sid='test-session', file_store=mock_file_store)
# Create a mock agent
agent = MockAgent()
# Create a mock agent controller
controller = AgentController(
agent=agent,
event_stream=event_stream,
convo_stats=convo_stats,
iteration_delta=10,
budget_per_task_delta=None,
sid='test-session',
)
# Set up the agent state
await controller.set_agent_state_to(AgentState.RUNNING)
# Create an MCP action
mcp_action = MCPAction(
name='test_tool',
arguments={'param': 'value'},
thought='Testing MCP timeout handling',
)
# Add the action to the event stream
event_stream.add_event(mcp_action, EventSource.AGENT)
# Set the pending action
controller._pending_action = mcp_action
# Now implement the fix in call_tool_mcp
async def fixed_call_tool_mcp(clients, action):
try:
# This will raise the McpError
await mock_client.call_tool(action.name, action.arguments)
except McpError as e:
# Create an error observation
error_content = json.dumps(
{'isError': True, 'error': str(e), 'content': []}
)
observation = MCPObservation(
content=error_content,
name=action.name,
arguments=action.arguments,
)
# Set the cause
setattr(observation, '_cause', action.id)
return observation
# Use our fixed function
with mock.patch(
'openhands.mcp.utils.call_tool_mcp', side_effect=fixed_call_tool_mcp
):
# Call the function that would normally be called by the agent controller
result = await call_tool_mcp([mock_client], mcp_action)
# Verify that the function returns an error observation
assert isinstance(result, MCPObservation)
content = json.loads(result.content)
assert content['isError'] is True
assert 'timed out' in content['error'].lower()
# Now simulate the agent controller's handling of the observation
event_stream.add_event(result, EventSource.ENVIRONMENT)
# Verify that the pending action is cleared
controller._pending_action = None
# Verify that the agent is still in the RUNNING state
assert controller.get_agent_state() == AgentState.RUNNING
# Verify that the agent can continue processing
agent.next_action = MCPAction(
name='another_tool',
arguments={'param': 'value'},
thought='Another action after timeout',
)
# Simulate a step
await controller._step()
# Verify that the agent was asked to step
assert agent.step_called