name : threadexception.py import threading import traceback import warnings from types import TracebackType from typing import Any from typing import Callable from typing import Generator from typing import Optional from typing import Type import pytest # Copied from cpython/Lib/test/support/threading_helper.py, with modifications. class catch_threading_exception: """Context manager catching threading.Thread exception using threading.excepthook. Storing exc_value using a custom hook can create a reference cycle. The reference cycle is broken explicitly when the context manager exits. Storing thread using a custom hook can resurrect it if it is set to an object which is being finalized. Exiting the context manager clears the stored object. Usage: with threading_helper.catch_threading_exception() as cm: # code spawning a thread which raises an exception ... # check the thread exception: use cm.args ... # cm.args attribute no longer exists at this point # (to break a reference cycle) """ def __init__(self) -> None: self.args: Optional["threading.ExceptHookArgs"] = None self._old_hook: Optional[Callable[["threading.ExceptHookArgs"], Any]] = None def _hook(self, args: "threading.ExceptHookArgs") -> None: self.args = args def __enter__(self) -> "catch_threading_exception": self._old_hook = threading.excepthook threading.excepthook = self._hook return self def __exit__( self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> None: assert self._old_hook is not None threading.excepthook = self._old_hook self._old_hook = None del self.args def thread_exception_runtest_hook() -> Generator[None, None, None]: with catch_threading_exception() as cm: yield if cm.args: thread_name = "<unknown>" if cm.args.thread is None else cm.args.thread.name msg = f"Exception in thread {thread_name}\n\n" msg += "".join( traceback.format_exception( cm.args.exc_type, cm.args.exc_value, cm.args.exc_traceback, ) ) warnings.warn(pytest.PytestUnhandledThreadExceptionWarning(msg)) @pytest.hookimpl(hookwrapper=True, trylast=True) def pytest_runtest_setup() -> Generator[None, None, None]: yield from thread_exception_runtest_hook() @pytest.hookimpl(hookwrapper=True, tryfirst=True) def pytest_runtest_call() -> Generator[None, None, None]: yield from thread_exception_runtest_hook() @pytest.hookimpl(hookwrapper=True, tryfirst=True) def pytest_runtest_teardown() -> Generator[None, None, None]: yield from thread_exception_runtest_hook()