__init__.py

"""Supporting definitions for the Python regression tests."""

if __name__ != 'test.support':
    raise ImportError('support must be imported from the test package')

import contextlib
import dataclasses
import functools
import logging
import _opcode
import os
import re
import stat
import sys
import sysconfig
import textwrap
import time
import types
import unittest
import warnings


__all__ = [
    # globals
    "PIPE_MAX_SIZE", "verbose", "max_memuse", "use_resources", "failfast",
    # exceptions
    "Error", "TestFailed", "TestDidNotRun", "ResourceDenied",
    # io
    "record_original_stdout", "get_original_stdout", "captured_stdout",
    "captured_stdin", "captured_stderr", "captured_output",
    # unittest
    "is_resource_enabled", "requires", "requires_freebsd_version",
    "requires_gil_enabled", "requires_linux_version", "requires_mac_ver",
    "check_syntax_error",
    "requires_gzip", "requires_bz2", "requires_lzma",
    "bigmemtest", "bigaddrspacetest", "cpython_only", "get_attribute",
    "requires_IEEE_754", "requires_zlib",
    "has_fork_support", "requires_fork",
    "has_subprocess_support", "requires_subprocess",
    "has_socket_support", "requires_working_socket",
    "anticipate_failure", "load_package_tests", "detect_api_mismatch",
    "check__all__", "skip_if_buggy_ucrt_strfptime",
    "check_disallow_instantiation", "check_sanitizer", "skip_if_sanitizer",
    "requires_limited_api", "requires_specialization",
    # sys
    "MS_WINDOWS", "is_jython", "is_android", "is_emscripten", "is_wasi",
    "is_apple_mobile", "check_impl_detail", "unix_shell", "setswitchinterval",
    # os
    "get_pagesize",
    # network
    "open_urlresource",
    # processes
    "reap_children",
    # miscellaneous
    "run_with_locale", "swap_item", "findfile", "infinite_recursion",
    "swap_attr", "Matcher", "set_memlimit", "SuppressCrashReport", "sortdict",
    "run_with_tz", "PGO", "missing_compiler_executable",
    "ALWAYS_EQ", "NEVER_EQ", "LARGEST", "SMALLEST",
    "LOOPBACK_TIMEOUT", "INTERNET_TIMEOUT", "SHORT_TIMEOUT", "LONG_TIMEOUT",
    "Py_DEBUG", "exceeds_recursion_limit", "get_c_recursion_limit",
    "skip_on_s390x",
    "without_optimizer",
    "force_not_colorized",
    "force_not_colorized_test_class",
    "make_clean_env",
    "BrokenIter",
    ]


# Timeout in seconds for tests using a network server listening on the network
# local loopback interface like 127.0.0.1.
#
# The timeout is long enough to prevent test failure: it takes into account
# that the client and the server can run in different threads or even different
# processes.
#
# The timeout should be long enough for connect(), recv() and send() methods
# of socket.socket.
LOOPBACK_TIMEOUT = 10.0

# Timeout in seconds for network requests going to the internet. The timeout is
# short enough to prevent a test to wait for too long if the internet request
# is blocked for whatever reason.
#
# Usually, a timeout using INTERNET_TIMEOUT should not mark a test as failed,
# but skip the test instead: see transient_internet().
INTERNET_TIMEOUT = 60.0

# Timeout in seconds to mark a test as failed if the test takes "too long".
#
# The timeout value depends on the regrtest --timeout command line option.
#
# If a test using SHORT_TIMEOUT starts to fail randomly on slow buildbots, use
# LONG_TIMEOUT instead.
SHORT_TIMEOUT = 30.0

# Timeout in seconds to detect when a test hangs.
#
# It is long enough to reduce the risk of test failure on the slowest Python
# buildbots. It should not be used to mark a test as failed if the test takes
# "too long". The timeout value depends on the regrtest --timeout command line
# option.
LONG_TIMEOUT = 5 * 60.0

# TEST_HOME_DIR refers to the top level directory of the "test" package
# that contains Python's regression test suite
TEST_SUPPORT_DIR = os.path.dirname(os.path.abspath(__file__))
TEST_HOME_DIR = os.path.dirname(TEST_SUPPORT_DIR)
STDLIB_DIR = os.path.dirname(TEST_HOME_DIR)
REPO_ROOT = os.path.dirname(STDLIB_DIR)


class Error(Exception):
    """Base class for regression test exceptions."""

class TestFailed(Error):
    """Test failed."""
    def __init__(self, msg, *args, stats=None):
        self.msg = msg
        self.stats = stats
        super().__init__(msg, *args)

    def __str__(self):
        return self.msg

class TestFailedWithDetails(TestFailed):
    """Test failed."""
    def __init__(self, msg, errors, failures, stats):
        self.errors = errors
        self.failures = failures
        super().__init__(msg, errors, failures, stats=stats)

class TestDidNotRun(Error):
    """Test did not run any subtests."""

class ResourceDenied(unittest.SkipTest):
    """Test skipped because it requested a disallowed resource.

    This is raised when a test calls requires() for a resource that
    has not be enabled.  It is used to distinguish between expected
    and unexpected skips.
    """

def anticipate_failure(condition):
    """Decorator to mark a test that is known to be broken in some cases

       Any use of this decorator should have a comment identifying the
       associated tracker issue.
    """
    if condition:
        return unittest.expectedFailure
    return lambda f: f

def load_package_tests(pkg_dir, loader, standard_tests, pattern):
    """Generic load_tests implementation for simple test packages.

    Most packages can implement load_tests using this function as follows:

       def load_tests(*args):
           return load_package_tests(os.path.dirname(__file__), *args)
    """
    if pattern is None:
        pattern = "test*"
    top_dir = STDLIB_DIR
    package_tests = loader.discover(start_dir=pkg_dir,
                                    top_level_dir=top_dir,
                                    pattern=pattern)
    standard_tests.addTests(package_tests)
    return standard_tests


def get_attribute(obj, name):
    """Get an attribute, raising SkipTest if AttributeError is raised."""
    try:
        attribute = getattr(obj, name)
    except AttributeError:
        raise unittest.SkipTest("object %r has no attribute %r" % (obj, name))
    else:
        return attribute

verbose = 1              # Flag set to 0 by regrtest.py
use_resources = None     # Flag set to [] by regrtest.py
max_memuse = 0           # Disable bigmem tests (they will still be run with
                         # small sizes, to make sure they work.)
real_max_memuse = 0
junit_xml_list = None    # list of testsuite XML elements
failfast = False

# _original_stdout is meant to hold stdout at the time regrtest began.
# This may be "the real" stdout, or IDLE's emulation of stdout, or whatever.
# The point is to have some flavor of stdout the user can actually see.
_original_stdout = None
def record_original_stdout(stdout):
    global _original_stdout
    _original_stdout = stdout

def get_original_stdout():
    return _original_stdout or sys.stdout


def _force_run(path, func, *args):
    try:
        return func(*args)
    except FileNotFoundError as err:
        # chmod() won't fix a missing file.
        if verbose >= 2:
            print('%s: %s' % (err.__class__.__name__, err))
        raise
    except OSError as err:
        if verbose >= 2:
            print('%s: %s' % (err.__class__.__name__, err))
            print('re-run %s%r' % (func.__name__, args))
        os.chmod(path, stat.S_IRWXU)
        return func(*args)


# Check whether a gui is actually available
def _is_gui_available():
    if hasattr(_is_gui_available, 'result'):
        return _is_gui_available.result
    import platform
    reason = None
    if sys.platform.startswith('win') and platform.win32_is_iot():
        reason = "gui is not available on Windows IoT Core"
    elif sys.platform.startswith('win'):
        # if Python is running as a service (such as the buildbot service),
        # gui interaction may be disallowed
        import ctypes
        import ctypes.wintypes
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        if not bool(uof.dwFlags & WSF_VISIBLE):
            reason = "gui not available (WSF_VISIBLE flag not set)"
    elif sys.platform == 'darwin':
        # The Aqua Tk implementations on OS X can abort the process if
        # being called in an environment where a window server connection
        # cannot be made, for instance when invoked by a buildbot or ssh
        # process not running under the same user id as the current console
        # user.  To avoid that, raise an exception if the window manager
        # connection is not available.
        import subprocess
        try:
            rc = subprocess.run(["launchctl", "managername"],
                                capture_output=True, check=True)
            managername = rc.stdout.decode("utf-8").strip()
        except subprocess.CalledProcessError:
            reason = "unable to detect macOS launchd job manager"
        else:
            if managername != "Aqua":
                reason = f"{managername=} -- can only run in a macOS GUI session"

    # check on every platform whether tkinter can actually do anything
    if not reason:
        try:
            from tkinter import Tk
            root = Tk()
            root.withdraw()
            root.update()
            root.destroy()
        except Exception as e:
            err_string = str(e)
            if len(err_string) > 50:
                err_string = err_string[:50] + ' [...]'
            reason = 'Tk unavailable due to {}: {}'.format(type(e).__name__,
                                                           err_string)

    _is_gui_available.reason = reason
    _is_gui_available.result = not reason

    return _is_gui_available.result

def is_resource_enabled(resource):
    """Test whether a resource is enabled.

    Known resources are set by regrtest.py.  If not running under regrtest.py,
    all resources are assumed enabled unless use_resources has been set.
    """
    return use_resources is None or resource in use_resources

def requires(resource, msg=None):
    """Raise ResourceDenied if the specified resource is not available."""
    if not is_resource_enabled(resource):
        if msg is None:
            msg = "Use of the %r resource not enabled" % resource
        raise ResourceDenied(msg)
    if resource in {"network", "urlfetch"} and not has_socket_support:
        raise ResourceDenied("No socket support")
    if resource == 'gui' and not _is_gui_available():
        raise ResourceDenied(_is_gui_available.reason)

def _get_kernel_version(sysname="Linux"):
    import platform
    if platform.system() != sysname:
        return None
    version_txt = platform.release().split('-', 1)[0]
    try:
        return tuple(map(int, version_txt.split('.')))
    except ValueError:
        return None

def _requires_unix_version(sysname, min_version):
    """Decorator raising SkipTest if the OS is `sysname` and the version is less
    than `min_version`.

    For example, @_requires_unix_version('FreeBSD', (7, 2)) raises SkipTest if
    the FreeBSD version is less than 7.2.
    """
    import platform
    min_version_txt = '.'.join(map(str, min_version))
    version_txt = platform.release().split('-', 1)[0]
    if platform.system() == sysname:
        try:
            version = tuple(map(int, version_txt.split('.')))
        except ValueError:
            skip = False
        else:
            skip = version < min_version
    else:
        skip = False

    return unittest.skipIf(
        skip,
        f"{sysname} version {min_version_txt} or higher required, not "
        f"{version_txt}"
    )


def requires_freebsd_version(*min_version):
    """Decorator raising SkipTest if the OS is FreeBSD and the FreeBSD version is
    less than `min_version`.

    For example, @requires_freebsd_version(7, 2) raises SkipTest if the FreeBSD
    version is less than 7.2.
    """
    return _requires_unix_version('FreeBSD', min_version)

def requires_linux_version(*min_version):
    """Decorator raising SkipTest if the OS is Linux and the Linux version is
    less than `min_version`.

    For example, @requires_linux_version(2, 6, 32) raises SkipTest if the Linux
    version is less than 2.6.32.
    """
    return _requires_unix_version('Linux', min_version)

def requires_mac_ver(*min_version):
    """Decorator raising SkipTest if the OS is Mac OS X and the OS X
    version if less than min_version.

    For example, @requires_mac_ver(10, 5) raises SkipTest if the OS X version
    is lesser than 10.5.
    """
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kw):
            if sys.platform == 'darwin':
                import platform
                version_txt = platform.mac_ver()[0]
                try:
                    version = tuple(map(int, version_txt.split('.')))
                except ValueError:
                    pass
                else:
                    if version < min_version:
                        min_version_txt = '.'.join(map(str, min_version))
                        raise unittest.SkipTest(
                            "Mac OS X %s or higher required, not %s"
                            % (min_version_txt, version_txt))
            return func(*args, **kw)
        wrapper.min_version = min_version
        return wrapper
    return decorator


def skip_if_buildbot(reason=None):
    """Decorator raising SkipTest if running on a buildbot."""
    import getpass
    if not reason:
        reason = 'not suitable for buildbots'
    try:
        isbuildbot = getpass.getuser().lower() == 'buildbot'
    except (KeyError, OSError) as err:
        logging.getLogger(__name__).warning('getpass.getuser() failed %s.', err, exc_info=err)
        isbuildbot = False
    return unittest.skipIf(isbuildbot, reason)

def check_sanitizer(*, address=False, memory=False, ub=False, thread=False):
    """Returns True if Python is compiled with sanitizer support"""
    if not (address or memory or ub or thread):
        raise ValueError('At least one of address, memory, ub or thread must be True')


    cflags = sysconfig.get_config_var('CFLAGS') or ''
    config_args = sysconfig.get_config_var('CONFIG_ARGS') or ''
    memory_sanitizer = (
        '-fsanitize=memory' in cflags or
        '--with-memory-sanitizer' in config_args
    )
    address_sanitizer = (
        '-fsanitize=address' in cflags or
        '--with-address-sanitizer' in config_args
    )
    ub_sanitizer = (
        '-fsanitize=undefined' in cflags or
        '--with-undefined-behavior-sanitizer' in config_args
    )
    thread_sanitizer = (
        '-fsanitize=thread' in cflags or
        '--with-thread-sanitizer' in config_args
    )
    return (
        (memory and memory_sanitizer) or
        (address and address_sanitizer) or
        (ub and ub_sanitizer) or
        (thread and thread_sanitizer)
    )


def skip_if_sanitizer(reason=None, *, address=False, memory=False, ub=False, thread=False):
    """Decorator raising SkipTest if running with a sanitizer active."""
    if not reason:
        reason = 'not working with sanitizers active'
    skip = check_sanitizer(address=address, memory=memory, ub=ub, thread=thread)
    return unittest.skipIf(skip, reason)

# gh-89363: True if fork() can hang if Python is built with Address Sanitizer
# (ASAN): libasan race condition, dead lock in pthread_create().
HAVE_ASAN_FORK_BUG = check_sanitizer(address=True)


def set_sanitizer_env_var(env, option):
    for name in ('ASAN_OPTIONS', 'MSAN_OPTIONS', 'UBSAN_OPTIONS', 'TSAN_OPTIONS'):
        if name in env:
            env[name] += f':{option}'
        else:
            env[name] = option


def system_must_validate_cert(f):
    """Skip the test on TLS certificate validation failures."""
    @functools.wraps(f)
    def dec(*args, **kwargs):
        try:
            f(*args, **kwargs)
        except OSError as e:
            if "CERTIFICATE_VERIFY_FAILED" in str(e):
                raise unittest.SkipTest("system does not contain "
                                        "necessary certificates")
            raise
    return dec

# A constant likely larger than the underlying OS pipe buffer size, to
# make writes blocking.
# Windows limit seems to be around 512 B, and many Unix kernels have a
# 64 KiB pipe buffer size or 16 * PAGE_SIZE: take a few megs to be sure.
# (see issue #17835 for a discussion of this number).
PIPE_MAX_SIZE = 4 * 1024 * 1024 + 1

# A constant likely larger than the underlying OS socket buffer size, to make
# writes blocking.
# The socket buffer sizes can usually be tuned system-wide (e.g. through sysctl
# on Linux), or on a per-socket basis (SO_SNDBUF/SO_RCVBUF).  See issue #18643
# for a discussion of this number.
SOCK_MAX_SIZE = 16 * 1024 * 1024 + 1

# decorator for skipping tests on non-IEEE 754 platforms
requires_IEEE_754 = unittest.skipUnless(
    float.__getformat__("double").startswith("IEEE"),
    "test requires IEEE 754 doubles")

def requires_zlib(reason='requires zlib'):
    try:
        import zlib
    except ImportError:
        zlib = None
    return unittest.skipUnless(zlib, reason)

def requires_gzip(reason='requires gzip'):
    try:
        import gzip
    except ImportError:
        gzip = None
    return unittest.skipUnless(gzip, reason)

def requires_bz2(reason='requires bz2'):
    try:
        import bz2
    except ImportError:
        bz2 = None
    return unittest.skipUnless(bz2, reason)

def requires_lzma(reason='requires lzma'):
    try:
        import lzma
    except ImportError:
        lzma = None
    lzma = None # XXX: RUSTPYTHON; xz is not supported yet
    return unittest.skipUnless(lzma, reason)

def has_no_debug_ranges():
    try:
        import _testinternalcapi
    except ImportError:
        raise unittest.SkipTest("_testinternalcapi required")
    config = _testinternalcapi.get_config()
    return not bool(config['code_debug_ranges'])

def requires_debug_ranges(reason='requires co_positions / debug_ranges'):
    try:
        skip = has_no_debug_ranges()
    except unittest.SkipTest as e:
        skip = True
        reason = e.args[0] if e.args else reason
    return unittest.skipIf(skip, reason)


def can_use_suppress_immortalization(suppress=True):
    """Check if suppress_immortalization(suppress) can be used.

    Use this helper in code where SkipTest must be eagerly handled.
    """
    if not suppress:
        return True
    try:
        import _testinternalcapi
    except ImportError:
        return False
    return True


@contextlib.contextmanager
def suppress_immortalization(suppress=True):
    """Suppress immortalization of deferred objects.

    If _testinternalcapi is not available, the decorated test or class
    is skipped. Use can_use_suppress_immortalization() outside test cases
    to check if this decorator can be used.
    """
    if not suppress:
        yield  # no-op
        return

    from .import_helper import import_module

    _testinternalcapi = import_module("_testinternalcapi")
    _testinternalcapi.suppress_immortalization(True)
    try:
        yield
    finally:
        _testinternalcapi.suppress_immortalization(False)


def skip_if_suppress_immortalization():
    try:
        import _testinternalcapi
    except ImportError:
        return
    return unittest.skipUnless(_testinternalcapi.get_immortalize_deferred(),
                                "requires immortalization of deferred objects")


MS_WINDOWS = (sys.platform == 'win32')

# Is not actually used in tests, but is kept for compatibility.
is_jython = sys.platform.startswith('java')

is_android = sys.platform == "android"

if sys.platform not in {"win32", "vxworks", "ios", "tvos", "watchos"}:
    unix_shell = '/system/bin/sh' if is_android else '/bin/sh'
else:
    unix_shell = None

# wasm32-emscripten and -wasi are POSIX-like but do not
# have subprocess or fork support.
is_emscripten = sys.platform == "emscripten"
is_wasi = sys.platform == "wasi"

is_apple_mobile = sys.platform in {"ios", "tvos", "watchos"}
is_apple = is_apple_mobile or sys.platform == "darwin"

has_fork_support = hasattr(os, "fork") and not (
    # WASM and Apple mobile platforms do not support subprocesses.
    is_emscripten
    or is_wasi
    or is_apple_mobile

    # Although Android supports fork, it's unsafe to call it from Python because
    # all Android apps are multi-threaded.
    or is_android
)

def requires_fork():
    return unittest.skipUnless(has_fork_support, "requires working os.fork()")

has_subprocess_support = not (
    # WASM and Apple mobile platforms do not support subprocesses.
    is_emscripten
    or is_wasi
    or is_apple_mobile

    # Although Android supports subproceses, they're almost never useful in
    # practice (see PEP 738). And most of the tests that use them are calling
    # sys.executable, which won't work when Python is embedded in an Android app.
    or is_android
)

def requires_subprocess():
    """Used for subprocess, os.spawn calls, fd inheritance"""
    return unittest.skipUnless(has_subprocess_support, "requires subprocess support")

# Emscripten's socket emulation and WASI sockets have limitations.
has_socket_support = not (
    is_emscripten
    or is_wasi
)

def requires_working_socket(*, module=False):
    """Skip tests or modules that require working sockets

    Can be used as a function/class decorator or to skip an entire module.
    """
    msg = "requires socket support"
    if module:
        if not has_socket_support:
            raise unittest.SkipTest(msg)
    else:
        return unittest.skipUnless(has_socket_support, msg)

# Does strftime() support glibc extension like '%4Y'?
has_strftime_extensions = False
if sys.platform != "win32":
    # bpo-47037: Windows debug builds crash with "Debug Assertion Failed"
    try:
        has_strftime_extensions = time.strftime("%4Y") != "%4Y"
    except ValueError:
        pass

# Define the URL of a dedicated HTTP server for the network tests.
# The URL must use clear-text HTTP: no redirection to encrypted HTTPS.
TEST_HTTP_URL = "http://www.pythontest.net"

# Set by libregrtest/main.py so we can skip tests that are not
# useful for PGO
PGO = False

# Set by libregrtest/main.py if we are running the extended (time consuming)
# PGO task.  If this is True, PGO is also True.
PGO_EXTENDED = False

# TEST_DATA_DIR is used as a target download location for remote resources
TEST_DATA_DIR = os.path.join(TEST_HOME_DIR, "data")


def darwin_malloc_err_warning(test_name):
    """Assure user that loud errors generated by macOS libc's malloc are
    expected."""
    if sys.platform != 'darwin':
        return

    import shutil
    msg = ' NOTICE '
    detail = (f'{test_name} may generate "malloc can\'t allocate region"\n'
              'warnings on macOS systems. This behavior is known. Do not\n'
              'report a bug unless tests are also failing.\n'
              'See https://github.com/python/cpython/issues/85100')

    padding, _ = shutil.get_terminal_size()
    print(msg.center(padding, '-'))
    print(detail)
    print('-' * padding)


def findfile(filename, subdir=None):
    """Try to find a file on sys.path or in the test directory.  If it is not
    found the argument passed to the function is returned (this does not
    necessarily signal failure; could still be the legitimate path).

    Setting *subdir* indicates a relative path to use to find the file
    rather than looking directly in the path directories.
    """
    if os.path.isabs(filename):
        return filename
    if subdir is not None:
        filename = os.path.join(subdir, filename)
    path = [TEST_HOME_DIR] + sys.path
    for dn in path:
        fn = os.path.join(dn, filename)
        if os.path.exists(fn): return fn
    return filename


def sortdict(dict):
    "Like repr(dict), but in sorted order."
    items = sorted(dict.items())
    reprpairs = ["%r: %r" % pair for pair in items]
    withcommas = ", ".join(reprpairs)
    return "{%s}" % withcommas


def run_code(code: str) -> dict[str, object]:
    """Run a piece of code after dedenting it, and return its global namespace."""
    ns = {}
    exec(textwrap.dedent(code), ns)
    return ns


def check_syntax_error(testcase, statement, errtext='', *, lineno=None, offset=None):
    with testcase.assertRaisesRegex(SyntaxError, errtext) as cm:
        compile(statement, '<test string>', 'exec')
    err = cm.exception
    testcase.assertIsNotNone(err.lineno)
    if lineno is not None:
        testcase.assertEqual(err.lineno, lineno)
    testcase.assertIsNotNone(err.offset)
    if offset is not None:
        testcase.assertEqual(err.offset, offset)


def open_urlresource(url, *args, **kw):
    import urllib.request, urllib.parse
    from .os_helper import unlink
    try:
        import gzip
    except ImportError:
        gzip = None

    check = kw.pop('check', None)

    filename = urllib.parse.urlparse(url)[2].split('/')[-1] # '/': it's URL!

    fn = os.path.join(TEST_DATA_DIR, filename)

    def check_valid_file(fn):
        f = open(fn, *args, **kw)
        if check is None:
            return f
        elif check(f):
            f.seek(0)
            return f
        f.close()

    if os.path.exists(fn):
        f = check_valid_file(fn)
        if f is not None:
            return f
        unlink(fn)

    # Verify the requirement before downloading the file
    requires('urlfetch')

    if verbose:
        print('\tfetching %s ...' % url, file=get_original_stdout())
    opener = urllib.request.build_opener()
    if gzip:
        opener.addheaders.append(('Accept-Encoding', 'gzip'))
    f = opener.open(url, timeout=INTERNET_TIMEOUT)
    if gzip and f.headers.get('Content-Encoding') == 'gzip':
        f = gzip.GzipFile(fileobj=f)
    try:
        with open(fn, "wb") as out:
            s = f.read()
            while s:
                out.write(s)
                s = f.read()
    finally:
        f.close()

    f = check_valid_file(fn)
    if f is not None:
        return f
    raise TestFailed('invalid resource %r' % fn)


@contextlib.contextmanager
def captured_output(stream_name):
    """Return a context manager used by captured_stdout/stdin/stderr
    that temporarily replaces the sys stream *stream_name* with a StringIO."""
    import io
    orig_stdout = getattr(sys, stream_name)
    setattr(sys, stream_name, io.StringIO())
    try:
        yield getattr(sys, stream_name)
    finally:
        setattr(sys, stream_name, orig_stdout)

def captured_stdout():
    """Capture the output of sys.stdout:

       with captured_stdout() as stdout:
           print("hello")
       self.assertEqual(stdout.getvalue(), "hello\\n")
    """
    return captured_output("stdout")

def captured_stderr():
    """Capture the output of sys.stderr:

       with captured_stderr() as stderr:
           print("hello", file=sys.stderr)
       self.assertEqual(stderr.getvalue(), "hello\\n")
    """
    return captured_output("stderr")

def captured_stdin():
    """Capture the input to sys.stdin:

       with captured_stdin() as stdin:
           stdin.write('hello\\n')
           stdin.seek(0)
           # call test code that consumes from sys.stdin
           captured = input()
       self.assertEqual(captured, "hello")
    """
    return captured_output("stdin")


def gc_collect():
    """Force as many objects as possible to be collected.

    In non-CPython implementations of Python, this is needed because timely
    deallocation is not guaranteed by the garbage collector.  (Even in CPython
    this can be the case in case of reference cycles.)  This means that __del__
    methods may be called later than expected and weakrefs may remain alive for
    longer than expected.  This function tries its best to force all garbage
    objects to disappear.
    """
    return # TODO: RUSTPYTHON

    import gc
    gc.collect()
    gc.collect()
    gc.collect()

@contextlib.contextmanager
def disable_gc():
    # TODO: RUSTPYTHON; GC is not supported yet
    try:
        yield
    finally:
        pass
    return

    import gc
    have_gc = gc.isenabled()
    gc.disable()
    try:
        yield
    finally:
        if have_gc:
            gc.enable()

@contextlib.contextmanager
def gc_threshold(*args):
    # TODO: RUSTPYTHON; GC is not supported yet
    try:
        yield
    finally:
        pass
    return

    import gc
    old_threshold = gc.get_threshold()
    gc.set_threshold(*args)
    try:
        yield
    finally:
        gc.set_threshold(*old_threshold)

def python_is_optimized():
    """Find if Python was built with optimizations."""
    cflags = sysconfig.get_config_var('PY_CFLAGS') or ''
    final_opt = ""
    for opt in cflags.split():
        if opt.startswith('-O'):
            final_opt = opt
    if sysconfig.get_config_var("CC") == "gcc":
        non_opts = ('', '-O0', '-Og')
    else:
        non_opts = ('', '-O0')
    return final_opt not in non_opts


def check_cflags_pgo():
    # Check if Python was built with ./configure --enable-optimizations:
    # with Profile Guided Optimization (PGO).
    cflags_nodist = sysconfig.get_config_var('PY_CFLAGS_NODIST') or ''
    pgo_options = [
        # GCC
        '-fprofile-use',
        # clang: -fprofile-instr-use=code.profclangd
        '-fprofile-instr-use',
        # ICC
        "-prof-use",
    ]
    PGO_PROF_USE_FLAG = sysconfig.get_config_var('PGO_PROF_USE_FLAG')
    if PGO_PROF_USE_FLAG:
        pgo_options.append(PGO_PROF_USE_FLAG)
    return any(option in cflags_nodist for option in pgo_options)


def check_bolt_optimized():
    # Always return false, if the platform is WASI,
    # because BOLT optimization does not support WASM binary.
    if is_wasi:
        return False
    config_args = sysconfig.get_config_var('CONFIG_ARGS') or ''
    return '--enable-bolt' in config_args


Py_GIL_DISABLED = bool(sysconfig.get_config_var('Py_GIL_DISABLED'))

def requires_gil_enabled(msg="needs the GIL enabled"):
    """Decorator for skipping tests on the free-threaded build."""
    return unittest.skipIf(Py_GIL_DISABLED, msg)

def expected_failure_if_gil_disabled():
    """Expect test failure if the GIL is disabled."""
    if Py_GIL_DISABLED:
        return unittest.expectedFailure
    return lambda test_case: test_case

if Py_GIL_DISABLED:
    _header = 'PHBBInP'
else:
    _header = 'nP'
_align = '0n'
_vheader = _header + 'n'

def calcobjsize(fmt):
    import struct
    return struct.calcsize(_header + fmt + _align)

def calcvobjsize(fmt):
    import struct
    return struct.calcsize(_vheader + fmt + _align)


_TPFLAGS_HAVE_GC = 1<<14
_TPFLAGS_HEAPTYPE = 1<<9

def check_sizeof(test, o, size):
    try:
        import _testinternalcapi
    except ImportError:
        raise unittest.SkipTest("_testinternalcapi required")
    result = sys.getsizeof(o)
    # add GC header size
    if ((type(o) == type) and (o.__flags__ & _TPFLAGS_HEAPTYPE) or\
        ((type(o) != type) and (type(o).__flags__ & _TPFLAGS_HAVE_GC))):
        size += _testinternalcapi.SIZEOF_PYGC_HEAD
    msg = 'wrong size for %s: got %d, expected %d' \
            % (type(o), result, size)
    test.assertEqual(result, size, msg)

def subTests(arg_names, arg_values, /, *, _do_cleanups=False):
    """Run multiple subtests with different parameters.
    """
    single_param = False
    if isinstance(arg_names, str):
        arg_names = arg_names.replace(',',' ').split()
        if len(arg_names) == 1:
            single_param = True
    arg_values = tuple(arg_values)
    def decorator(func):
        if isinstance(func, type):
            raise TypeError('subTests() can only decorate methods, not classes')
        @functools.wraps(func)
        def wrapper(self, /, *args, **kwargs):
            for values in arg_values:
                if single_param:
                    values = (values,)
                subtest_kwargs = dict(zip(arg_names, values))
                with self.subTest(**subtest_kwargs):
                    func(self, *args, **kwargs, **subtest_kwargs)
                if _do_cleanups:
                    self.doCleanups()
        return wrapper
    return decorator

#=======================================================================
# Decorator/context manager for running a code in a different locale,
# correctly resetting it afterwards.