Should SocketBlockedError etc also inherit from OSError?

[djrobstep]

urllib3 for instance, raises OSError here which I presume we would want to catch?

[djrobstep]

Happy to create PR if that's useful.

[miketheman]

Maybe, but probably not? Can you share an example of how that would be materially useful?

[djrobstep]

Because when used with urllib3, the socket is not cleaned up properly without it, leading to ResourceWarnings

[miketheman]

Can you share an example of some test and code that would surface this issue?

[djrobstep]

Sure, this test for example finds unclosed sockets, but adding a conftest that monkeypatches the Error classes to inherit from OSError fixes it.

Run with: pytest test_unclosed_socket.py --disable-socket --allow-hosts=127.0.0.1 -v

test:

import socket
from unittest.mock import patch

import urllib3


def test_blocked_connect_does_not_leak_socket():
    """urllib3 should not leak a socket when pytest-socket blocks connect()."""
    created_sockets = []
    original_init = socket.socket.__init__

    def tracking_init(self, *args, **kwargs):
        original_init(self, *args, **kwargs)
        created_sockets.append(self)

    with patch.object(socket.socket, "__init__", tracking_init):
        pool = urllib3.HTTPConnectionPool("10.255.255.1", 9999)
        try:
            pool.urlopen("GET", "/", retries=0, timeout=0.1)
        except Exception:
            pass

    try:
        assert created_sockets, "Expected at least one socket to be created"
        for sock in created_sockets:
            assert sock.fileno() == -1, (
                f"Socket was not closed (fd={sock.fileno()}). "
                "This is the pytest-socket bug: SocketConnectBlockedError(RuntimeError) "
                "bypasses urllib3's `except OSError` cleanup. "
                "Fix by making it inherit from OSError too."
            )
    finally:
        # Clean up any leaked sockets so this test doesn't leak them itself.
        for sock in created_sockets:
            try:
                sock.close()
            except OSError:
                pass

conftest.py (add this to make the test pass):

import pytest_socket


class SocketBlockedError(RuntimeError, OSError):
    def __init__(self, *_args, **_kwargs):
        super().__init__("A test tried to use socket.socket.")


class SocketConnectBlockedError(RuntimeError, OSError):
    def __init__(self, allowed, host, *_args, **_kwargs):
        if allowed:
            allowed = ",".join(allowed)
        super().__init__(
            f'A test tried to use socket.socket.connect() '
            f'with host "{host}" (allowed: "{allowed}").'
        )


pytest_socket.SocketBlockedError = SocketBlockedError
pytest_socket.SocketConnectBlockedError = SocketConnectBlockedError