test_ok2/testing/test_faulthandler.py

import io
import sys

import pytest
from _pytest.pytester import Pytester


def test_enabled(pytester: Pytester) -> None:
    """Test single crashing test displays a traceback."""
    pytester.makepyfile(
        """
    import faulthandler
    def test_crash():
        faulthandler._sigabrt()
    """
    )
    result = pytester.runpytest_subprocess()
    result.stderr.fnmatch_lines(["*Fatal Python error*"])
    assert result.ret != 0


def test_crash_near_exit(pytester: Pytester) -> None:
    """Test that fault handler displays crashes that happen even after
    pytest is exiting (for example, when the interpreter is shutting down)."""
    pytester.makepyfile(
        """
    import faulthandler
    import atexit
    def test_ok():
        atexit.register(faulthandler._sigabrt)
    """
    )
    result = pytester.runpytest_subprocess()
    result.stderr.fnmatch_lines(["*Fatal Python error*"])
    assert result.ret != 0


def test_disabled(pytester: Pytester) -> None:
    """Test option to disable fault handler in the command line."""
    pytester.makepyfile(
        """
    import faulthandler
    def test_disabled():
        assert not faulthandler.is_enabled()
    """
    )
    result = pytester.runpytest_subprocess("-p", "no:faulthandler")
    result.stdout.fnmatch_lines(["*1 passed*"])
    assert result.ret == 0


@pytest.mark.parametrize(
    "enabled",
    [
        pytest.param(
            True, marks=pytest.mark.skip(reason="sometimes crashes on CI (#7022)")
        ),
        False,
    ],
)
def test_timeout(pytester: Pytester, enabled: bool) -> None:
    """Test option to dump tracebacks after a certain timeout.

    If faulthandler is disabled, no traceback will be dumped.
    """
    pytester.makepyfile(
        """
    import os, time
    def test_timeout():
        time.sleep(1 if "CI" in os.environ else 0.1)
    """
    )
    pytester.makeini(
        """
        [pytest]
        faulthandler_timeout = 0.01
        """
    )
    args = ["-p", "no:faulthandler"] if not enabled else []

    result = pytester.runpytest_subprocess(*args)
    tb_output = "most recent call first"
    if enabled:
        result.stderr.fnmatch_lines(["*%s*" % tb_output])
    else:
        assert tb_output not in result.stderr.str()
    result.stdout.fnmatch_lines(["*1 passed*"])
    assert result.ret == 0


@pytest.mark.parametrize("hook_name", ["pytest_enter_pdb", "pytest_exception_interact"])
def test_cancel_timeout_on_hook(monkeypatch, hook_name) -> None:
    """Make sure that we are cancelling any scheduled traceback dumping due
    to timeout before entering pdb (pytest-dev/pytest-faulthandler#12) or any
    other interactive exception (pytest-dev/pytest-faulthandler#14)."""
    import faulthandler
    from _pytest.faulthandler import FaultHandlerHooks

    called = []

    monkeypatch.setattr(
        faulthandler, "cancel_dump_traceback_later", lambda: called.append(1)
    )

    # call our hook explicitly, we can trust that pytest will call the hook
    # for us at the appropriate moment
    hook_func = getattr(FaultHandlerHooks, hook_name)
    hook_func(self=None)
    assert called == [1]


@pytest.mark.parametrize("faulthandler_timeout", [0, 2])
def test_already_initialized(faulthandler_timeout: int, pytester: Pytester) -> None:
    """Test for faulthandler being initialized earlier than pytest (#6575)."""
    pytester.makepyfile(
        """
        def test():
            import faulthandler
            assert faulthandler.is_enabled()
    """
    )
    result = pytester.run(
        sys.executable,
        "-X",
        "faulthandler",
        "-mpytest",
        pytester.path,
        "-o",
        f"faulthandler_timeout={faulthandler_timeout}",
    )
    # ensure warning is emitted if faulthandler_timeout is configured
    warning_line = "*faulthandler.py*faulthandler module enabled before*"
    if faulthandler_timeout > 0:
        result.stdout.fnmatch_lines(warning_line)
    else:
        result.stdout.no_fnmatch_line(warning_line)
    result.stdout.fnmatch_lines("*1 passed*")
    assert result.ret == 0


def test_get_stderr_fileno_invalid_fd() -> None:
    """Test for faulthandler being able to handle invalid file descriptors for stderr (#8249)."""
    from _pytest.faulthandler import FaultHandlerHooks

    class StdErrWrapper(io.StringIO):
        """
        Mimic ``twisted.logger.LoggingFile`` to simulate returning an invalid file descriptor.

        https://github.com/twisted/twisted/blob/twisted-20.3.0/src/twisted/logger/_io.py#L132-L139
        """

        def fileno(self):
            return -1

    wrapper = StdErrWrapper()

    with pytest.MonkeyPatch.context() as mp:
        mp.setattr("sys.stderr", wrapper)

        # Even when the stderr wrapper signals an invalid file descriptor,
        # ``_get_stderr_fileno()`` should return the real one.
        assert FaultHandlerHooks._get_stderr_fileno() == 2