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Testing Stuck Detection Patterns and Error Handling in OpenHands

This test suite validates the stuck detection functionality in OpenHands, focusing on identifying and handling various stuck scenarios in agent-based interactions. It covers both headless and interactive modes, testing pattern recognition and error handling capabilities.

Test Coverage Overview

The test suite provides comprehensive coverage of stuck detection scenarios including:
  • Repeating action-observation patterns
  • Syntax error detection
  • Interactive mode behavior
  • Error observation loops
  • Monologue detection
Key edge cases include varying line numbers, different error types, and state management across user interactions.

Implementation Analysis

The testing approach uses pytest fixtures and mocking to simulate agent interactions and validate stuck detection logic.
Key patterns include:
  • State management through history tracking
  • Event stream simulation
  • Mock logging verification
  • Parametrized test scenarios

Technical Details

Testing tools and configuration:
  • pytest for test framework
  • unittest.mock for mocking components
  • TempPathFactory for temporary file handling
  • Logging configuration for debug output
  • Custom fixtures for state and detector initialization

Best Practices Demonstrated

The test suite exemplifies quality testing practices through:
  • Comprehensive fixture setup and teardown
  • Isolated test cases with clear scenarios
  • Thorough edge case coverage
  • Mock verification of logging calls
  • Clean test organization with descriptive names

all-hands-ai/openhands

tests/unit/test_is_stuck.py

            
import logging
from unittest.mock import Mock, patch

import pytest
from pytest import TempPathFactory

from openhands.controller.agent_controller import AgentController
from openhands.controller.state.state import State
from openhands.controller.stuck import StuckDetector
from openhands.events.action import CmdRunAction, FileReadAction, MessageAction
from openhands.events.action.commands import IPythonRunCellAction
from openhands.events.observation import (
    CmdOutputObservation,
    FileReadObservation,
)
from openhands.events.observation.commands import IPythonRunCellObservation
from openhands.events.observation.empty import NullObservation
from openhands.events.observation.error import ErrorObservation
from openhands.events.stream import EventSource, EventStream
from openhands.storage import get_file_store


def collect_events(stream):
    return [event for event in stream.get_events()]


logging.basicConfig(level=logging.DEBUG)

jupyter_line_1 = '
[Jupyter current working directory:'
jupyter_line_2 = '
[Jupyter Python interpreter:'
code_snippet = """
edit_file_by_replace(
    'book_store.py',
    to_replace=\"""def total(basket):
    if not basket:
        return 0
"""


@pytest.fixture
def temp_dir(tmp_path_factory: TempPathFactory) -> str:
    return str(tmp_path_factory.mktemp('test_is_stuck'))


@pytest.fixture
def event_stream(temp_dir):
    file_store = get_file_store('local', temp_dir)
    event_stream = EventStream('asdf', file_store)
    yield event_stream
    # clear after each test
    event_stream.clear()


class TestStuckDetector:
    @pytest.fixture
    def stuck_detector(self):
        state = State(inputs={}, max_iterations=50)
        state.history = []  # Initialize history as an empty list
        return StuckDetector(state)

    def _impl_syntax_error_events(
        self,
        state: State,
        error_message: str,
        random_line: bool,
        incidents: int = 4,
    ):
        for i in range(incidents):
            ipython_action = IPythonRunCellAction(code=code_snippet)
            state.history.append(ipython_action)
            extra_number = (i + 1) * 10 if random_line else '42'
            extra_line = '
' * (i + 1) if random_line else ''
            ipython_observation = IPythonRunCellObservation(
                content=f'  Cell In[1], line {extra_number}
'
                'to_replace="""def largest(min_factor, max_factor):
            ^
'
                f'{error_message}{extra_line}' + jupyter_line_1 + jupyter_line_2,
                code=code_snippet,
            )
            # ipython_observation._cause = ipython_action._id
            state.history.append(ipython_observation)

    def _impl_unterminated_string_error_events(
        self, state: State, random_line: bool, incidents: int = 4
    ):
        for i in range(incidents):
            ipython_action = IPythonRunCellAction(code=code_snippet)
            state.history.append(ipython_action)
            line_number = (i + 1) * 10 if random_line else '1'
            ipython_observation = IPythonRunCellObservation(
                content=f'print("  Cell In[1], line {line_number}
hello
       ^
SyntaxError: unterminated string literal (detected at line {line_number})'
                + jupyter_line_1
                + jupyter_line_2,
                code=code_snippet,
            )
            # ipython_observation._cause = ipython_action._
            state.history.append(ipython_observation)

    def test_history_too_short(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        message_action = MessageAction(content='Hello', wait_for_response=False)
        message_action._source = EventSource.USER
        observation = NullObservation(content='')
        # observation._cause = message_action.id
        state.history.append(message_action)
        state.history.append(observation)

        cmd_action = CmdRunAction(command='ls')
        state.history.append(cmd_action)
        cmd_observation = CmdOutputObservation(
            command_id=1, command='ls', content='file1.txt
file2.txt'
        )
        # cmd_observation._cause = cmd_action._id
        state.history.append(cmd_observation)

        assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_interactive_mode_resets_after_user_message(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state

        # First add some actions that would be stuck in non-UI mode
        for i in range(4):
            cmd_action = CmdRunAction(command='ls')
            cmd_action._id = i
            state.history.append(cmd_action)
            cmd_observation = CmdOutputObservation(
                content='', command='ls', command_id=i
            )
            cmd_observation._cause = cmd_action._id
            state.history.append(cmd_observation)

        # In headless mode, this should be stuck
        assert stuck_detector.is_stuck(headless_mode=True) is True

        # with the UI, it will ALSO be stuck initially
        assert stuck_detector.is_stuck(headless_mode=False) is True

        # Add a user message
        message_action = MessageAction(content='Hello', wait_for_response=False)
        message_action._source = EventSource.USER
        state.history.append(message_action)

        # In not-headless mode, this should not be stuck because we ignore history before user message
        assert stuck_detector.is_stuck(headless_mode=False) is False

        # But in headless mode, this should be still stuck because user messages do not count
        assert stuck_detector.is_stuck(headless_mode=True) is True

        # Add two more identical actions - still not stuck because we need at least 3
        for i in range(2):
            cmd_action = CmdRunAction(command='ls')
            cmd_action._id = i + 4
            state.history.append(cmd_action)
            cmd_observation = CmdOutputObservation(
                content='', command='ls', command_id=i + 4
            )
            cmd_observation._cause = cmd_action._id
            state.history.append(cmd_observation)

        assert stuck_detector.is_stuck(headless_mode=False) is False

        # Add two more identical actions - now it should be stuck
        for i in range(2):
            cmd_action = CmdRunAction(command='ls')
            cmd_action._id = i + 6
            state.history.append(cmd_action)
            cmd_observation = CmdOutputObservation(
                content='', command='ls', command_id=i + 6
            )
            cmd_observation._cause = cmd_action._id
            state.history.append(cmd_observation)

        assert stuck_detector.is_stuck(headless_mode=False) is True

    def test_is_stuck_repeating_action_observation(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        message_action = MessageAction(content='Done', wait_for_response=False)
        message_action._source = EventSource.USER

        hello_action = MessageAction(content='Hello', wait_for_response=False)
        hello_observation = NullObservation('')

        # 2 events
        state.history.append(hello_action)
        state.history.append(hello_observation)

        cmd_action_1 = CmdRunAction(command='ls')
        cmd_action_1._id = 1
        state.history.append(cmd_action_1)
        cmd_observation_1 = CmdOutputObservation(content='', command='ls', command_id=1)
        cmd_observation_1._cause = cmd_action_1._id
        state.history.append(cmd_observation_1)
        # 4 events

        cmd_action_2 = CmdRunAction(command='ls')
        cmd_action_2._id = 2
        state.history.append(cmd_action_2)
        cmd_observation_2 = CmdOutputObservation(content='', command='ls', command_id=2)
        cmd_observation_2._cause = cmd_action_2._id
        state.history.append(cmd_observation_2)
        # 6 events

        # random user message just because we can
        message_null_observation = NullObservation(content='')
        state.history.append(message_action)
        state.history.append(message_null_observation)
        # 8 events

        assert stuck_detector.is_stuck(headless_mode=True) is False

        cmd_action_3 = CmdRunAction(command='ls')
        cmd_action_3._id = 3
        state.history.append(cmd_action_3)
        cmd_observation_3 = CmdOutputObservation(content='', command='ls', command_id=3)
        cmd_observation_3._cause = cmd_action_3._id
        state.history.append(cmd_observation_3)
        # 10 events

        assert len(state.history) == 10
        assert stuck_detector.is_stuck(headless_mode=True) is False

        cmd_action_4 = CmdRunAction(command='ls')
        cmd_action_4._id = 4
        state.history.append(cmd_action_4)
        cmd_observation_4 = CmdOutputObservation(content='', command='ls', command_id=4)
        cmd_observation_4._cause = cmd_action_4._id
        state.history.append(cmd_observation_4)
        # 12 events

        assert len(state.history) == 12

        with patch('logging.Logger.warning') as mock_warning:
            assert stuck_detector.is_stuck(headless_mode=True) is True
            mock_warning.assert_called_once_with('Action, Observation loop detected')

    def test_is_stuck_repeating_action_error(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        # (action, error_observation), not necessarily the same error
        message_action = MessageAction(content='Done', wait_for_response=False)
        message_action._source = EventSource.USER

        hello_action = MessageAction(content='Hello', wait_for_response=False)
        hello_observation = NullObservation(content='')
        state.history.append(hello_action)
        # hello_observation._cause = hello_action._id
        state.history.append(hello_observation)
        # 2 events

        cmd_action_1 = CmdRunAction(command='invalid_command')
        state.history.append(cmd_action_1)
        error_observation_1 = ErrorObservation(content='Command not found')
        # error_observation_1._cause = cmd_action_1._id
        state.history.append(error_observation_1)
        # 4 events

        cmd_action_2 = CmdRunAction(command='invalid_command')
        state.history.append(cmd_action_2)
        error_observation_2 = ErrorObservation(
            content='Command still not found or another error'
        )
        # error_observation_2._cause = cmd_action_2._id
        state.history.append(error_observation_2)
        # 6 events

        message_null_observation = NullObservation(content='')
        state.history.append(message_action)
        state.history.append(message_null_observation)
        # 8 events

        cmd_action_3 = CmdRunAction(command='invalid_command')
        state.history.append(cmd_action_3)
        error_observation_3 = ErrorObservation(content='Different error')
        # error_observation_3._cause = cmd_action_3._id
        state.history.append(error_observation_3)
        # 10 events

        cmd_action_4 = CmdRunAction(command='invalid_command')
        state.history.append(cmd_action_4)
        error_observation_4 = ErrorObservation(content='Command not found')
        # error_observation_4._cause = cmd_action_4._id
        state.history.append(error_observation_4)
        # 12 events

        with patch('logging.Logger.warning') as mock_warning:
            assert stuck_detector.is_stuck(headless_mode=True) is True
            mock_warning.assert_called_once_with(
                'Action, ErrorObservation loop detected'
            )

    def test_is_stuck_invalid_syntax_error(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        self._impl_syntax_error_events(
            state,
            error_message='SyntaxError: invalid syntax. Perhaps you forgot a comma?',
            random_line=False,
        )

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is True

    def test_is_not_stuck_invalid_syntax_error_random_lines(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        self._impl_syntax_error_events(
            state,
            error_message='SyntaxError: invalid syntax. Perhaps you forgot a comma?',
            random_line=True,
        )

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_is_not_stuck_invalid_syntax_error_only_three_incidents(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        self._impl_syntax_error_events(
            state,
            error_message='SyntaxError: invalid syntax. Perhaps you forgot a comma?',
            random_line=True,
            incidents=3,
        )

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_is_stuck_incomplete_input_error(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        self._impl_syntax_error_events(
            state,
            error_message='SyntaxError: incomplete input',
            random_line=False,
        )

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is True

    def test_is_not_stuck_incomplete_input_error(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        self._impl_syntax_error_events(
            state,
            error_message='SyntaxError: incomplete input',
            random_line=True,
        )

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_is_not_stuck_ipython_unterminated_string_error_random_lines(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        self._impl_unterminated_string_error_events(state, random_line=True)

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_is_not_stuck_ipython_unterminated_string_error_only_three_incidents(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        self._impl_unterminated_string_error_events(
            state, random_line=False, incidents=3
        )

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_is_stuck_ipython_unterminated_string_error(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        self._impl_unterminated_string_error_events(state, random_line=False)

        with patch('logging.Logger.warning'):
            assert stuck_detector.is_stuck(headless_mode=True) is True

    def test_is_not_stuck_ipython_syntax_error_not_at_end(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        # this test is to make sure we don't get false positives
        # since the "at line x" is changing in between!
        ipython_action_1 = IPythonRunCellAction(code='print("hello')
        state.history.append(ipython_action_1)
        ipython_observation_1 = IPythonRunCellObservation(
            content='print("hello
       ^
SyntaxError: unterminated string literal (detected at line 1)
This is some additional output',
            code='print("hello',
        )
        # ipython_observation_1._cause = ipython_action_1._id
        state.history.append(ipython_observation_1)

        ipython_action_2 = IPythonRunCellAction(code='print("hello')
        state.history.append(ipython_action_2)
        ipython_observation_2 = IPythonRunCellObservation(
            content='print("hello
       ^
SyntaxError: unterminated string literal (detected at line 1)
Too much output here on and on',
            code='print("hello',
        )
        # ipython_observation_2._cause = ipython_action_2._id
        state.history.append(ipython_observation_2)

        ipython_action_3 = IPythonRunCellAction(code='print("hello')
        state.history.append(ipython_action_3)
        ipython_observation_3 = IPythonRunCellObservation(
            content='print("hello
       ^
SyntaxError: unterminated string literal (detected at line 3)
Enough',
            code='print("hello',
        )
        # ipython_observation_3._cause = ipython_action_3._id
        state.history.append(ipython_observation_3)

        ipython_action_4 = IPythonRunCellAction(code='print("hello')
        state.history.append(ipython_action_4)
        ipython_observation_4 = IPythonRunCellObservation(
            content='print("hello
       ^
SyntaxError: unterminated string literal (detected at line 2)
Last line of output',
            code='print("hello',
        )
        # ipython_observation_4._cause = ipython_action_4._id
        state.history.append(ipython_observation_4)

        with patch('logging.Logger.warning') as mock_warning:
            assert stuck_detector.is_stuck(headless_mode=True) is False
            mock_warning.assert_not_called()

    def test_is_stuck_repeating_action_observation_pattern(
        self, stuck_detector: StuckDetector
    ):
        state = stuck_detector.state
        message_action = MessageAction(content='Come on', wait_for_response=False)
        message_action._source = EventSource.USER
        state.history.append(message_action)
        message_observation = NullObservation(content='')
        state.history.append(message_observation)

        cmd_action_1 = CmdRunAction(command='ls')
        state.history.append(cmd_action_1)
        cmd_observation_1 = CmdOutputObservation(
            command_id=1, command='ls', content='file1.txt
file2.txt'
        )
        # cmd_observation_1._cause = cmd_action_1._id
        state.history.append(cmd_observation_1)

        read_action_1 = FileReadAction(path='file1.txt')
        state.history.append(read_action_1)
        read_observation_1 = FileReadObservation(
            content='File content', path='file1.txt'
        )
        # read_observation_1._cause = read_action_1._id
        state.history.append(read_observation_1)

        cmd_action_2 = CmdRunAction(command='ls')
        state.history.append(cmd_action_2)
        cmd_observation_2 = CmdOutputObservation(
            command_id=2, command='ls', content='file1.txt
file2.txt'
        )
        # cmd_observation_2._cause = cmd_action_2._id
        state.history.append(cmd_observation_2)

        read_action_2 = FileReadAction(path='file1.txt')
        state.history.append(read_action_2)
        read_observation_2 = FileReadObservation(
            content='File content', path='file1.txt'
        )
        # read_observation_2._cause = read_action_2._id
        state.history.append(read_observation_2)

        message_action = MessageAction(content='Come on', wait_for_response=False)
        message_action._source = EventSource.USER
        state.history.append(message_action)

        message_null_observation = NullObservation(content='')
        state.history.append(message_null_observation)

        cmd_action_3 = CmdRunAction(command='ls')
        state.history.append(cmd_action_3)
        cmd_observation_3 = CmdOutputObservation(
            command_id=3, command='ls', content='file1.txt
file2.txt'
        )
        # cmd_observation_3._cause = cmd_action_3._id
        state.history.append(cmd_observation_3)

        read_action_3 = FileReadAction(path='file1.txt')
        state.history.append(read_action_3)
        read_observation_3 = FileReadObservation(
            content='File content', path='file1.txt'
        )
        # read_observation_3._cause = read_action_3._id
        state.history.append(read_observation_3)

        with patch('logging.Logger.warning') as mock_warning:
            assert stuck_detector.is_stuck(headless_mode=True) is True
            mock_warning.assert_called_once_with('Action, Observation pattern detected')

    def test_is_stuck_not_stuck(self, stuck_detector: StuckDetector):
        state = stuck_detector.state
        message_action = MessageAction(content='Done', wait_for_response=False)
        message_action._source = EventSource.USER

        hello_action = MessageAction(content='Hello', wait_for_response=False)
        state.history.append(hello_action)
        hello_observation = NullObservation(content='')
        # hello_observation._cause = hello_action._id
        state.history.append(hello_observation)

        cmd_action_1 = CmdRunAction(command='ls')
        state.history.append(cmd_action_1)
        cmd_observation_1 = CmdOutputObservation(
            command_id=cmd_action_1.id, command='ls', content='file1.txt
file2.txt'
        )
        # cmd_observation_1._cause = cmd_action_1._id
        state.history.append(cmd_observation_1)

        read_action_1 = FileReadAction(path='file1.txt')
        state.history.append(read_action_1)
        read_observation_1 = FileReadObservation(
            content='File content', path='file1.txt'
        )
        # read_observation_1._cause = read_action_1._id
        state.history.append(read_observation_1)

        cmd_action_2 = CmdRunAction(command='pwd')
        state.history.append(cmd_action_2)
        cmd_observation_2 = CmdOutputObservation(
            command_id=2, command='pwd', content='/home/user'
        )
        # cmd_observation_2._cause = cmd_action_2._id
        state.history.append(cmd_observation_2)

        read_action_2 = FileReadAction(path='file2.txt')
        state.history.append(read_action_2)
        read_observation_2 = FileReadObservation(
            content='Another file content', path='file2.txt'
        )
        # read_observation_2._cause = read_action_2._id
        state.history.append(read_observation_2)

        message_null_observation = NullObservation(content='')
        state.history.append(message_action)
        state.history.append(message_null_observation)

        cmd_action_3 = CmdRunAction(command='pwd')
        state.history.append(cmd_action_3)
        cmd_observation_3 = CmdOutputObservation(
            command_id=cmd_action_3.id, command='pwd', content='/home/user'
        )
        # cmd_observation_3._cause = cmd_action_3._id
        state.history.append(cmd_observation_3)

        read_action_3 = FileReadAction(path='file2.txt')
        state.history.append(read_action_3)
        read_observation_3 = FileReadObservation(
            content='Another file content', path='file2.txt'
        )
        # read_observation_3._cause = read_action_3._id
        state.history.append(read_observation_3)

        assert stuck_detector.is_stuck(headless_mode=True) is False

    def test_is_stuck_monologue(self, stuck_detector):
        state = stuck_detector.state
        # Add events to the history list directly
        message_action_1 = MessageAction(content='Hi there!')
        message_action_1._source = EventSource.USER
        state.history.append(message_action_1)
        message_action_2 = MessageAction(content='Hi there!')
        message_action_2._source = EventSource.AGENT
        state.history.append(message_action_2)
        message_action_3 = MessageAction(content='How are you?')
        message_action_3._source = EventSource.USER
        state.history.append(message_action_3)

        cmd_kill_action = CmdRunAction(
            command='echo 42', thought="I'm not stuck, he's stuck"
        )
        state.history.append(cmd_kill_action)

        message_action_4 = MessageAction(content="I'm doing well, thanks for asking.")
        message_action_4._source = EventSource.AGENT
        state.history.append(message_action_4)
        message_action_5 = MessageAction(content="I'm doing well, thanks for asking.")
        message_action_5._source = EventSource.AGENT
        state.history.append(message_action_5)
        message_action_6 = MessageAction(content="I'm doing well, thanks for asking.")
        message_action_6._source = EventSource.AGENT
        state.history.append(message_action_6)

        assert stuck_detector.is_stuck(headless_mode=True)

        # Add an observation event between the repeated message actions
        cmd_output_observation = CmdOutputObservation(
            content='OK, I was stuck, but no more.',
            command_id=42,
            command='storybook',
            exit_code=0,
        )
        # cmd_output_observation._cause = cmd_kill_action._id
        state.history.append(cmd_output_observation)

        message_action_7 = MessageAction(content="I'm doing well, thanks for asking.")
        message_action_7._source = EventSource.AGENT
        state.history.append(message_action_7)
        message_action_8 = MessageAction(content="I'm doing well, thanks for asking.")
        message_action_8._source = EventSource.AGENT
        state.history.append(message_action_8)

        with patch('logging.Logger.warning'):
            assert not stuck_detector.is_stuck(headless_mode=True)


class TestAgentController:
    @pytest.fixture
    def controller(self):
        controller = Mock(spec=AgentController)
        controller._is_stuck = AgentController._is_stuck.__get__(
            controller, AgentController
        )
        controller.delegate = None
        controller.state = Mock()
        return controller

    def test_is_stuck_delegate_stuck(self, controller: AgentController):
        controller.delegate = Mock()
        controller.delegate._is_stuck.return_value = True
        assert controller._is_stuck() is True