Lib/test/test_sys.py

from test import support
from test.support.script_helper import assert_python_ok, assert_python_failure
import builtins
import codecs
import gc
import io
import locale
import operator
import os
import struct
import subprocess
import sys
import sysconfig
import test.support
import textwrap
import unittest
import warnings


# count the number of test runs, used to create unique
# strings to intern in test_intern()
INTERN_NUMRUNS = 0


class DisplayHookTest(unittest.TestCase):

    def test_original_displayhook(self):
        dh = sys.__displayhook__

        with support.captured_stdout() as out:
            dh(42)

        self.assertEqual(out.getvalue(), "42\n")
        self.assertEqual(builtins._, 42)

        del builtins._

        with support.captured_stdout() as out:
            dh(None)

        self.assertEqual(out.getvalue(), "")
        self.assertTrue(not hasattr(builtins, "_"))

        # sys.displayhook() requires arguments
        self.assertRaises(TypeError, dh)

        stdout = sys.stdout
        try:
            del sys.stdout
            self.assertRaises(RuntimeError, dh, 42)
        finally:
            sys.stdout = stdout

    def test_lost_displayhook(self):
        displayhook = sys.displayhook
        try:
            del sys.displayhook
            code = compile("42", "<string>", "single")
            self.assertRaises(RuntimeError, eval, code)
        finally:
            sys.displayhook = displayhook

    def test_custom_displayhook(self):
        def baddisplayhook(obj):
            raise ValueError

        with support.swap_attr(sys, 'displayhook', baddisplayhook):
            code = compile("42", "<string>", "single")
            self.assertRaises(ValueError, eval, code)


class ExceptHookTest(unittest.TestCase):

    def test_original_excepthook(self):
        try:
            raise ValueError(42)
        except ValueError as exc:
            with support.captured_stderr() as err:
                sys.__excepthook__(*sys.exc_info())

        self.assertTrue(err.getvalue().endswith("ValueError: 42\n"))

        self.assertRaises(TypeError, sys.__excepthook__)

    def test_excepthook_bytes_filename(self):
        # bpo-37467: sys.excepthook() must not crash if a filename
        # is a bytes string
        with warnings.catch_warnings():
            warnings.simplefilter('ignore', BytesWarning)

            try:
                raise SyntaxError("msg", (b"bytes_filename", 123, 0, "text"))
            except SyntaxError as exc:
                with support.captured_stderr() as err:
                    sys.__excepthook__(*sys.exc_info())

        err = err.getvalue()
        self.assertIn("""  File "b'bytes_filename'", line 123\n""", err)
        self.assertIn("""    text\n""", err)
        self.assertTrue(err.endswith("SyntaxError: msg\n"))

    def test_excepthook(self):
        with test.support.captured_output("stderr") as stderr:
            sys.excepthook(1, '1', 1)
        self.assertTrue("TypeError: print_exception(): Exception expected for " \
                         "value, str found" in stderr.getvalue())

    # FIXME: testing the code for a lost or replaced excepthook in
    # Python/pythonrun.c::PyErr_PrintEx() is tricky.


class SysModuleTest(unittest.TestCase):

    def tearDown(self):
        test.support.reap_children()

    def test_exit(self):
        # call with two arguments
        self.assertRaises(TypeError, sys.exit, 42, 42)

        # call without argument
        with self.assertRaises(SystemExit) as cm:
            sys.exit()
        self.assertIsNone(cm.exception.code)

        rc, out, err = assert_python_ok('-c', 'import sys; sys.exit()')
        self.assertEqual(rc, 0)
        self.assertEqual(out, b'')
        self.assertEqual(err, b'')

        # call with integer argument
        with self.assertRaises(SystemExit) as cm:
            sys.exit(42)
        self.assertEqual(cm.exception.code, 42)

        # call with tuple argument with one entry
        # entry will be unpacked
        with self.assertRaises(SystemExit) as cm:
            sys.exit((42,))
        self.assertEqual(cm.exception.code, 42)

        # call with string argument
        with self.assertRaises(SystemExit) as cm:
            sys.exit("exit")
        self.assertEqual(cm.exception.code, "exit")

        # call with tuple argument with two entries
        with self.assertRaises(SystemExit) as cm:
            sys.exit((17, 23))
        self.assertEqual(cm.exception.code, (17, 23))

        # test that the exit machinery handles SystemExits properly
        rc, out, err = assert_python_failure('-c', 'raise SystemExit(47)')
        self.assertEqual(rc, 47)
        self.assertEqual(out, b'')
        self.assertEqual(err, b'')

        def check_exit_message(code, expected, **env_vars):
            rc, out, err = assert_python_failure('-c', code, **env_vars)
            self.assertEqual(rc, 1)
            self.assertEqual(out, b'')
            self.assertTrue(err.startswith(expected),
                "%s doesn't start with %s" % (ascii(err), ascii(expected)))

        # test that stderr buffer is flushed before the exit message is written
        # into stderr
        check_exit_message(
            r'import sys; sys.stderr.write("unflushed,"); sys.exit("message")',
            b"unflushed,message")

        # test that the exit message is written with backslashreplace error
        # handler to stderr
        check_exit_message(
            r'import sys; sys.exit("surrogates:\uDCFF")',
            b"surrogates:\\udcff")

        # test that the unicode message is encoded to the stderr encoding
        # instead of the default encoding (utf8)
        check_exit_message(
            r'import sys; sys.exit("h\xe9")',
            b"h\xe9", PYTHONIOENCODING='latin-1')

    def test_getdefaultencoding(self):
        self.assertRaises(TypeError, sys.getdefaultencoding, 42)
        # can't check more than the type, as the user might have changed it
        self.assertIsInstance(sys.getdefaultencoding(), str)

    # testing sys.settrace() is done in test_sys_settrace.py
    # testing sys.setprofile() is done in test_sys_setprofile.py

    def test_switchinterval(self):
        self.assertRaises(TypeError, sys.setswitchinterval)
        self.assertRaises(TypeError, sys.setswitchinterval, "a")
        self.assertRaises(ValueError, sys.setswitchinterval, -1.0)
        self.assertRaises(ValueError, sys.setswitchinterval, 0.0)
        orig = sys.getswitchinterval()
        # sanity check
        self.assertTrue(orig < 0.5, orig)
        try:
            for n in 0.00001, 0.05, 3.0, orig:
                sys.setswitchinterval(n)
                self.assertAlmostEqual(sys.getswitchinterval(), n)
        finally:
            sys.setswitchinterval(orig)

    def test_recursionlimit(self):
        self.assertRaises(TypeError, sys.getrecursionlimit, 42)
        oldlimit = sys.getrecursionlimit()
        self.assertRaises(TypeError, sys.setrecursionlimit)
        self.assertRaises(ValueError, sys.setrecursionlimit, -42)
        sys.setrecursionlimit(10000)
        self.assertEqual(sys.getrecursionlimit(), 10000)
        sys.setrecursionlimit(oldlimit)

    def test_recursionlimit_recovery(self):
        if hasattr(sys, 'gettrace') and sys.gettrace():
            self.skipTest('fatal error if run with a trace function')

        oldlimit = sys.getrecursionlimit()
        def f():
            f()
        try:
            for depth in (10, 25, 50, 75, 100, 250, 1000):
                try:
                    sys.setrecursionlimit(depth)
                except RecursionError:
                    # Issue #25274: The recursion limit is too low at the
                    # current recursion depth
                    continue

                # Issue #5392: test stack overflow after hitting recursion
                # limit twice
                self.assertRaises(RecursionError, f)
                self.assertRaises(RecursionError, f)
        finally:
            sys.setrecursionlimit(oldlimit)

    @test.support.cpython_only
    def test_setrecursionlimit_recursion_depth(self):
        # Issue #25274: Setting a low recursion limit must be blocked if the
        # current recursion depth is already higher than the "lower-water
        # mark". Otherwise, it may not be possible anymore to
        # reset the overflowed flag to 0.

        from _testcapi import get_recursion_depth

        def set_recursion_limit_at_depth(depth, limit):
            recursion_depth = get_recursion_depth()
            if recursion_depth >= depth:
                with self.assertRaises(RecursionError) as cm:
                    sys.setrecursionlimit(limit)
                self.assertRegex(str(cm.exception),
                                 "cannot set the recursion limit to [0-9]+ "
                                 "at the recursion depth [0-9]+: "
                                 "the limit is too low")
            else:
                set_recursion_limit_at_depth(depth, limit)

        oldlimit = sys.getrecursionlimit()
        try:
            sys.setrecursionlimit(1000)

            for limit in (10, 25, 50, 75, 100, 150, 200):
                # formula extracted from _Py_RecursionLimitLowerWaterMark()
                if limit > 200:
                    depth = limit - 50
                else:
                    depth = limit * 3 // 4
                set_recursion_limit_at_depth(depth, limit)
        finally:
            sys.setrecursionlimit(oldlimit)

    def test_recursionlimit_fatalerror(self):
        # A fatal error occurs if a second recursion limit is hit when recovering
        # from a first one.
        code = textwrap.dedent("""
            import sys

            def f():
                try:
                    f()
                except RecursionError:
                    f()

            sys.setrecursionlimit(%d)
            f()""")
        with test.support.SuppressCrashReport():
            for i in (50, 1000):
                sub = subprocess.Popen([sys.executable, '-c', code % i],
                    stderr=subprocess.PIPE)
                err = sub.communicate()[1]
                self.assertTrue(sub.returncode, sub.returncode)
                self.assertIn(
                    b"Fatal Python error: Cannot recover from stack overflow",
                    err)

    def test_getwindowsversion(self):
        # Raise SkipTest if sys doesn't have getwindowsversion attribute
        test.support.get_attribute(sys, "getwindowsversion")
        v = sys.getwindowsversion()
        self.assertEqual(len(v), 5)
        self.assertIsInstance(v[0], int)
        self.assertIsInstance(v[1], int)
        self.assertIsInstance(v[2], int)
        self.assertIsInstance(v[3], int)
        self.assertIsInstance(v[4], str)
        self.assertRaises(IndexError, operator.getitem, v, 5)
        self.assertIsInstance(v.major, int)
        self.assertIsInstance(v.minor, int)
        self.assertIsInstance(v.build, int)
        self.assertIsInstance(v.platform, int)
        self.assertIsInstance(v.service_pack, str)
        self.assertIsInstance(v.service_pack_minor, int)
        self.assertIsInstance(v.service_pack_major, int)
        self.assertIsInstance(v.suite_mask, int)
        self.assertIsInstance(v.product_type, int)
        self.assertEqual(v[0], v.major)
        self.assertEqual(v[1], v.minor)
        self.assertEqual(v[2], v.build)
        self.assertEqual(v[3], v.platform)
        self.assertEqual(v[4], v.service_pack)

        # This is how platform.py calls it. Make sure tuple
        #  still has 5 elements
        maj, min, buildno, plat, csd = sys.getwindowsversion()

    def test_call_tracing(self):
        self.assertRaises(TypeError, sys.call_tracing, type, 2)

    @unittest.skipUnless(hasattr(sys, "setdlopenflags"),
                         'test needs sys.setdlopenflags()')
    def test_dlopenflags(self):
        self.assertTrue(hasattr(sys, "getdlopenflags"))
        self.assertRaises(TypeError, sys.getdlopenflags, 42)
        oldflags = sys.getdlopenflags()
        self.assertRaises(TypeError, sys.setdlopenflags)
        sys.setdlopenflags(oldflags+1)
        self.assertEqual(sys.getdlopenflags(), oldflags+1)
        sys.setdlopenflags(oldflags)

    @test.support.refcount_test
    def test_refcount(self):
        # n here must be a global in order for this test to pass while
        # tracing with a python function.  Tracing calls PyFrame_FastToLocals
        # which will add a copy of any locals to the frame object, causing
        # the reference count to increase by 2 instead of 1.
        global n
        self.assertRaises(TypeError, sys.getrefcount)
        c = sys.getrefcount(None)
        n = None
        self.assertEqual(sys.getrefcount(None), c+1)
        del n
        self.assertEqual(sys.getrefcount(None), c)
        if hasattr(sys, "gettotalrefcount"):
            self.assertIsInstance(sys.gettotalrefcount(), int)

    def test_getframe(self):
        self.assertRaises(TypeError, sys._getframe, 42, 42)
        self.assertRaises(ValueError, sys._getframe, 2000000000)
        self.assertTrue(
            SysModuleTest.test_getframe.__code__ \
            is sys._getframe().f_code
        )

    # sys._current_frames() is a CPython-only gimmick.
    @test.support.reap_threads
    def test_current_frames(self):
        import threading
        import traceback

        # Spawn a thread that blocks at a known place.  Then the main
        # thread does sys._current_frames(), and verifies that the frames
        # returned make sense.
        entered_g = threading.Event()
        leave_g = threading.Event()
        thread_info = []  # the thread's id

        def f123():
            g456()

        def g456():
            thread_info.append(threading.get_ident())
            entered_g.set()
            leave_g.wait()

        t = threading.Thread(target=f123)
        t.start()
        entered_g.wait()

        # At this point, t has finished its entered_g.set(), although it's
        # impossible to guess whether it's still on that line or has moved on
        # to its leave_g.wait().
        self.assertEqual(len(thread_info), 1)
        thread_id = thread_info[0]

        d = sys._current_frames()
        for tid in d:
            self.assertIsInstance(tid, int)
            self.assertGreater(tid, 0)

        main_id = threading.get_ident()
        self.assertIn(main_id, d)
        self.assertIn(thread_id, d)

        # Verify that the captured main-thread frame is _this_ frame.
        frame = d.pop(main_id)
        self.assertTrue(frame is sys._getframe())

        # Verify that the captured thread frame is blocked in g456, called
        # from f123.  This is a litte tricky, since various bits of
        # threading.py are also in the thread's call stack.
        frame = d.pop(thread_id)
        stack = traceback.extract_stack(frame)
        for i, (filename, lineno, funcname, sourceline) in enumerate(stack):
            if funcname == "f123":
                break
        else:
            self.fail("didn't find f123() on thread's call stack")

        self.assertEqual(sourceline, "g456()")

        # And the next record must be for g456().
        filename, lineno, funcname, sourceline = stack[i+1]
        self.assertEqual(funcname, "g456")
        self.assertIn(sourceline, ["leave_g.wait()", "entered_g.set()"])

        # Reap the spawned thread.
        leave_g.set()
        t.join()

    def test_attributes(self):
        self.assertIsInstance(sys.api_version, int)
        self.assertIsInstance(sys.argv, list)
        self.assertIn(sys.byteorder, ("little", "big"))
        self.assertIsInstance(sys.builtin_module_names, tuple)
        self.assertIsInstance(sys.copyright, str)
        self.assertIsInstance(sys.exec_prefix, str)
        self.assertIsInstance(sys.base_exec_prefix, str)
        self.assertIsInstance(sys.executable, str)
        self.assertEqual(len(sys.float_info), 11)
        self.assertEqual(sys.float_info.radix, 2)
        self.assertEqual(len(sys.int_info), 2)
        self.assertTrue(sys.int_info.bits_per_digit % 5 == 0)
        self.assertTrue(sys.int_info.sizeof_digit >= 1)
        self.assertEqual(type(sys.int_info.bits_per_digit), int)
        self.assertEqual(type(sys.int_info.sizeof_digit), int)
        self.assertIsInstance(sys.hexversion, int)

        self.assertEqual(len(sys.hash_info), 9)
        self.assertLess(sys.hash_info.modulus, 2**sys.hash_info.width)
        # sys.hash_info.modulus should be a prime; we do a quick
        # probable primality test (doesn't exclude the possibility of
        # a Carmichael number)
        for x in range(1, 100):
            self.assertEqual(
                pow(x, sys.hash_info.modulus-1, sys.hash_info.modulus),
                1,
                "sys.hash_info.modulus {} is a non-prime".format(
                    sys.hash_info.modulus)
                )
        self.assertIsInstance(sys.hash_info.inf, int)
        self.assertIsInstance(sys.hash_info.nan, int)
        self.assertIsInstance(sys.hash_info.imag, int)
        algo = sysconfig.get_config_var("Py_HASH_ALGORITHM")
        if sys.hash_info.algorithm in {"fnv", "siphash24"}:
            self.assertIn(sys.hash_info.hash_bits, {32, 64})
            self.assertIn(sys.hash_info.seed_bits, {32, 64, 128})

            if algo == 1:
                self.assertEqual(sys.hash_info.algorithm, "siphash24")
            elif algo == 2:
                self.assertEqual(sys.hash_info.algorithm, "fnv")
            else:
                self.assertIn(sys.hash_info.algorithm, {"fnv", "siphash24"})
        else:
            # PY_HASH_EXTERNAL
            self.assertEqual(algo, 0)
        self.assertGreaterEqual(sys.hash_info.cutoff, 0)
        self.assertLess(sys.hash_info.cutoff, 8)

        self.assertIsInstance(sys.maxsize, int)
        self.assertIsInstance(sys.maxunicode, int)
        self.assertEqual(sys.maxunicode, 0x10FFFF)
        self.assertIsInstance(sys.platform, str)
        self.assertIsInstance(sys.prefix, str)
        self.assertIsInstance(sys.base_prefix, str)
        self.assertIsInstance(sys.version, str)
        vi = sys.version_info
        self.assertIsInstance(vi[:], tuple)
        self.assertEqual(len(vi), 5)
        self.assertIsInstance(vi[0], int)
        self.assertIsInstance(vi[1], int)
        self.assertIsInstance(vi[2], int)
        self.assertIn(vi[3], ("alpha", "beta", "candidate", "final"))
        self.assertIsInstance(vi[4], int)
        self.assertIsInstance(vi.major, int)
        self.assertIsInstance(vi.minor, int)
        self.assertIsInstance(vi.micro, int)
        self.assertIn(vi.releaselevel, ("alpha", "beta", "candidate", "final"))
        self.assertIsInstance(vi.serial, int)
        self.assertEqual(vi[0], vi.major)
        self.assertEqual(vi[1], vi.minor)
        self.assertEqual(vi[2], vi.micro)
        self.assertEqual(vi[3], vi.releaselevel)
        self.assertEqual(vi[4], vi.serial)
        self.assertTrue(vi > (1,0,0))
        self.assertIsInstance(sys.float_repr_style, str)
        self.assertIn(sys.float_repr_style, ('short', 'legacy'))
        if not sys.platform.startswith('win'):
            self.assertIsInstance(sys.abiflags, str)

    def test_thread_info(self):
        info = sys.thread_info
        self.assertEqual(len(info), 3)
        self.assertIn(info.name, ('nt', 'pthread', 'solaris', None))
        self.assertIn(info.lock, ('semaphore', 'mutex+cond', None))

    def test_43581(self):
        # Can't use sys.stdout, as this is a StringIO object when
        # the test runs under regrtest.
        self.assertEqual(sys.__stdout__.encoding, sys.__stderr__.encoding)

    def test_intern(self):
        global INTERN_NUMRUNS
        INTERN_NUMRUNS += 1
        self.assertRaises(TypeError, sys.intern)
        s = "never interned before" + str(INTERN_NUMRUNS)
        self.assertTrue(sys.intern(s) is s)
        s2 = s.swapcase().swapcase()
        self.assertTrue(sys.intern(s2) is s)

        # Subclasses of string can't be interned, because they
        # provide too much opportunity for insane things to happen.
        # We don't want them in the interned dict and if they aren't
        # actually interned, we don't want to create the appearance
        # that they are by allowing intern() to succeed.
        class S(str):
            def __hash__(self):
                return 123

        self.assertRaises(TypeError, sys.intern, S("abc"))

    def test_sys_flags(self):
        self.assertTrue(sys.flags)
        attrs = ("debug",
                 "inspect", "interactive", "optimize", "dont_write_bytecode",
                 "no_user_site", "no_site", "ignore_environment", "verbose",
                 "bytes_warning", "quiet", "hash_randomization", "isolated",
                 "dev_mode", "utf8_mode")
        for attr in attrs:
            self.assertTrue(hasattr(sys.flags, attr), attr)
            attr_type = bool if attr == "dev_mode" else int
            self.assertEqual(type(getattr(sys.flags, attr)), attr_type, attr)
        self.assertTrue(repr(sys.flags))
        self.assertEqual(len(sys.flags), len(attrs))

        self.assertIn(sys.flags.utf8_mode, {0, 1, 2})

    def assert_raise_on_new_sys_type(self, sys_attr):
        # Users are intentionally prevented from creating new instances of
        # sys.flags, sys.version_info, and sys.getwindowsversion.
        attr_type = type(sys_attr)
        with self.assertRaises(TypeError):
            attr_type()
        with self.assertRaises(TypeError):
            attr_type.__new__(attr_type)

    def test_sys_flags_no_instantiation(self):
        self.assert_raise_on_new_sys_type(sys.flags)

    def test_sys_version_info_no_instantiation(self):
        self.assert_raise_on_new_sys_type(sys.version_info)

    def test_sys_getwindowsversion_no_instantiation(self):
        # Skip if not being run on Windows.
        test.support.get_attribute(sys, "getwindowsversion")
        self.assert_raise_on_new_sys_type(sys.getwindowsversion())

    @test.support.cpython_only
    def test_clear_type_cache(self):
        sys._clear_type_cache()

    def test_ioencoding(self):
        env = dict(os.environ)

        # Test character: cent sign, encoded as 0x4A (ASCII J) in CP424,
        # not representable in ASCII.

        env["PYTHONIOENCODING"] = "cp424"
        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
                             stdout = subprocess.PIPE, env=env)
        out = p.communicate()[0].strip()
        expected = ("\xa2" + os.linesep).encode("cp424")
        self.assertEqual(out, expected)

        env["PYTHONIOENCODING"] = "ascii:replace"
        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
                             stdout = subprocess.PIPE, env=env)
        out = p.communicate()[0].strip()
        self.assertEqual(out, b'?')

        env["PYTHONIOENCODING"] = "ascii"
        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                             env=env)
        out, err = p.communicate()
        self.assertEqual(out, b'')
        self.assertIn(b'UnicodeEncodeError:', err)
        self.assertIn(rb"'\xa2'", err)

        env["PYTHONIOENCODING"] = "ascii:"
        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                             env=env)
        out, err = p.communicate()
        self.assertEqual(out, b'')
        self.assertIn(b'UnicodeEncodeError:', err)
        self.assertIn(rb"'\xa2'", err)

        env["PYTHONIOENCODING"] = ":surrogateescape"
        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xdcbd))'],
                             stdout=subprocess.PIPE, env=env)
        out = p.communicate()[0].strip()
        self.assertEqual(out, b'\xbd')

    @unittest.skipUnless(test.support.FS_NONASCII,
                         'requires OS support of non-ASCII encodings')
    @unittest.skipUnless(sys.getfilesystemencoding() == locale.getpreferredencoding(False),
                         'requires FS encoding to match locale')
    def test_ioencoding_nonascii(self):
        env = dict(os.environ)

        env["PYTHONIOENCODING"] = ""
        p = subprocess.Popen([sys.executable, "-c",
                                'print(%a)' % test.support.FS_NONASCII],
                                stdout=subprocess.PIPE, env=env)
        out = p.communicate()[0].strip()
        self.assertEqual(out, os.fsencode(test.support.FS_NONASCII))

    @unittest.skipIf(sys.base_prefix != sys.prefix,
                     'Test is not venv-compatible')
    def test_executable(self):
        # sys.executable should be absolute
        self.assertEqual(os.path.abspath(sys.executable), sys.executable)

        # Issue #7774: Ensure that sys.executable is an empty string if argv[0]
        # has been set to a non existent program name and Python is unable to
        # retrieve the real program name

        # For a normal installation, it should work without 'cwd'
        # argument. For test runs in the build directory, see #7774.
        python_dir = os.path.dirname(os.path.realpath(sys.executable))
        p = subprocess.Popen(
            ["nonexistent", "-c",
             'import sys; print(sys.executable.encode("ascii", "backslashreplace"))'],
            executable=sys.executable, stdout=subprocess.PIPE, cwd=python_dir)
        stdout = p.communicate()[0]
        executable = stdout.strip().decode("ASCII")
        p.wait()
        self.assertIn(executable, ["b''", repr(sys.executable.encode("ascii", "backslashreplace"))])

    def check_fsencoding(self, fs_encoding, expected=None):
        self.assertIsNotNone(fs_encoding)
        codecs.lookup(fs_encoding)
        if expected:
            self.assertEqual(fs_encoding, expected)

    def test_getfilesystemencoding(self):
        fs_encoding = sys.getfilesystemencoding()
        if sys.platform == 'darwin':
            expected = 'utf-8'
        else:
            expected = None
        self.check_fsencoding(fs_encoding, expected)

    def c_locale_get_error_handler(self, locale, isolated=False, encoding=None):
        # Force the POSIX locale
        env = os.environ.copy()
        env["LC_ALL"] = locale
        env["PYTHONCOERCECLOCALE"] = "0"
        code = '\n'.join((
            'import sys',
            'def dump(name):',
            '    std = getattr(sys, name)',
            '    print("%s: %s" % (name, std.errors))',
            'dump("stdin")',
            'dump("stdout")',
            'dump("stderr")',
        ))
        args = [sys.executable, "-X", "utf8=0", "-c", code]
        if isolated:
            args.append("-I")
        if encoding is not None:
            env['PYTHONIOENCODING'] = encoding
        else:
            env.pop('PYTHONIOENCODING', None)
        p = subprocess.Popen(args,
                              stdout=subprocess.PIPE,
                              stderr=subprocess.STDOUT,
                              env=env,
                              universal_newlines=True)
        stdout, stderr = p.communicate()
        return stdout

    def check_locale_surrogateescape(self, locale):
        out = self.c_locale_get_error_handler(locale, isolated=True)
        self.assertEqual(out,
                         'stdin: surrogateescape\n'
                         'stdout: surrogateescape\n'
                         'stderr: backslashreplace\n')

        # replace the default error handler
        out = self.c_locale_get_error_handler(locale, encoding=':ignore')
        self.assertEqual(out,
                         'stdin: ignore\n'
                         'stdout: ignore\n'
                         'stderr: backslashreplace\n')

        # force the encoding
        out = self.c_locale_get_error_handler(locale, encoding='iso8859-1')
        self.assertEqual(out,
                         'stdin: strict\n'
                         'stdout: strict\n'
                         'stderr: backslashreplace\n')
        out = self.c_locale_get_error_handler(locale, encoding='iso8859-1:')
        self.assertEqual(out,
                         'stdin: strict\n'
                         'stdout: strict\n'
                         'stderr: backslashreplace\n')

        # have no any effect
        out = self.c_locale_get_error_handler(locale, encoding=':')
        self.assertEqual(out,
                         'stdin: surrogateescape\n'
                         'stdout: surrogateescape\n'
                         'stderr: backslashreplace\n')
        out = self.c_locale_get_error_handler(locale, encoding='')
        self.assertEqual(out,
                         'stdin: surrogateescape\n'
                         'stdout: surrogateescape\n'
                         'stderr: backslashreplace\n')

    def test_c_locale_surrogateescape(self):
        self.check_locale_surrogateescape('C')

    def test_posix_locale_surrogateescape(self):
        self.check_locale_surrogateescape('POSIX')

    def test_implementation(self):
        # This test applies to all implementations equally.

        levels = {'alpha': 0xA, 'beta': 0xB, 'candidate': 0xC, 'final': 0xF}

        self.assertTrue(hasattr(sys.implementation, 'name'))
        self.assertTrue(hasattr(sys.implementation, 'version'))
        self.assertTrue(hasattr(sys.implementation, 'hexversion'))
        self.assertTrue(hasattr(sys.implementation, 'cache_tag'))

        version = sys.implementation.version
        self.assertEqual(version[:2], (version.major, version.minor))

        hexversion = (version.major << 24 | version.minor << 16 |
                      version.micro << 8 | levels[version.releaselevel] << 4 |
                      version.serial << 0)
        self.assertEqual(sys.implementation.hexversion, hexversion)

        # PEP 421 requires that .name be lower case.
        self.assertEqual(sys.implementation.name,
                         sys.implementation.name.lower())

    @test.support.cpython_only
    def test_debugmallocstats(self):
        # Test sys._debugmallocstats()
        from test.support.script_helper import assert_python_ok
        args = ['-c', 'import sys; sys._debugmallocstats()']
        ret, out, err = assert_python_ok(*args)
        self.assertIn(b"free PyDictObjects", err)

        # The function has no parameter
        self.assertRaises(TypeError, sys._debugmallocstats, True)

    @unittest.skipUnless(hasattr(sys, "getallocatedblocks"),
                         "sys.getallocatedblocks unavailable on this build")
    def test_getallocatedblocks(self):
        try:
            import _testcapi
        except ImportError:
            with_pymalloc = support.with_pymalloc()
        else:
            try:
                alloc_name = _testcapi.pymem_getallocatorsname()
            except RuntimeError as exc:
                # "cannot get allocators name" (ex: tracemalloc is used)
                with_pymalloc = True
            else:
                with_pymalloc = (alloc_name in ('pymalloc', 'pymalloc_debug'))

        # Some sanity checks
        a = sys.getallocatedblocks()
        self.assertIs(type(a), int)
        if with_pymalloc:
            self.assertGreater(a, 0)
        else:
            # When WITH_PYMALLOC isn't available, we don't know anything
            # about the underlying implementation: the function might
            # return 0 or something greater.
            self.assertGreaterEqual(a, 0)
        try:
            # While we could imagine a Python session where the number of
            # multiple buffer objects would exceed the sharing of references,
            # it is unlikely to happen in a normal test run.
            self.assertLess(a, sys.gettotalrefcount())
        except AttributeError:
            # gettotalrefcount() not available
            pass
        gc.collect()
        b = sys.getallocatedblocks()
        self.assertLessEqual(b, a)
        gc.collect()
        c = sys.getallocatedblocks()
        self.assertIn(c, range(b - 50, b + 50))

    @test.support.requires_type_collecting
    def test_is_finalizing(self):
        self.assertIs(sys.is_finalizing(), False)
        # Don't use the atexit module because _Py_Finalizing is only set
        # after calling atexit callbacks
        code = """if 1:
            import sys

            class AtExit:
                is_finalizing = sys.is_finalizing
                print = print

                def __del__(self):
                    self.print(self.is_finalizing(), flush=True)

            # Keep a reference in the __main__ module namespace, so the
            # AtExit destructor will be called at Python exit
            ref = AtExit()
        """
        rc, stdout, stderr = assert_python_ok('-c', code)
        self.assertEqual(stdout.rstrip(), b'True')

    @test.support.requires_type_collecting
    def test_issue20602(self):
        # sys.flags and sys.float_info were wiped during shutdown.
        code = """if 1:
            import sys
            class A:
                def __del__(self, sys=sys):
                    print(sys.flags)
                    print(sys.float_info)
            a = A()
            """
        rc, out, err = assert_python_ok('-c', code)
        out = out.splitlines()
        self.assertIn(b'sys.flags', out[0])
        self.assertIn(b'sys.float_info', out[1])

    @unittest.skipUnless(hasattr(sys, 'getandroidapilevel'),
                         'need sys.getandroidapilevel()')
    def test_getandroidapilevel(self):
        level = sys.getandroidapilevel()
        self.assertIsInstance(level, int)
        self.assertGreater(level, 0)

    def test_sys_tracebacklimit(self):
        code = """if 1:
            import sys
            def f1():
                1 / 0
            def f2():
                f1()
            sys.tracebacklimit = %r
            f2()
        """
        def check(tracebacklimit, expected):
            p = subprocess.Popen([sys.executable, '-c', code % tracebacklimit],
                                 stderr=subprocess.PIPE)
            out = p.communicate()[1]
            self.assertEqual(out.splitlines(), expected)

        traceback = [
            b'Traceback (most recent call last):',
            b'  File "<string>", line 8, in <module>',
            b'  File "<string>", line 6, in f2',
            b'  File "<string>", line 4, in f1',
            b'ZeroDivisionError: division by zero'
        ]
        check(10, traceback)
        check(3, traceback)
        check(2, traceback[:1] + traceback[2:])
        check(1, traceback[:1] + traceback[3:])
        check(0, [traceback[-1]])
        check(-1, [traceback[-1]])
        check(1<<1000, traceback)
        check(-1<<1000, [traceback[-1]])
        check(None, traceback)

    def test_no_duplicates_in_meta_path(self):
        self.assertEqual(len(sys.meta_path), len(set(sys.meta_path)))

    @unittest.skipUnless(hasattr(sys, "_enablelegacywindowsfsencoding"),
                         'needs sys._enablelegacywindowsfsencoding()')
    def test__enablelegacywindowsfsencoding(self):
        code = ('import sys',
                'sys._enablelegacywindowsfsencoding()',
                'print(sys.getfilesystemencoding(), sys.getfilesystemencodeerrors())')
        rc, out, err = assert_python_ok('-c', '; '.join(code))
        out = out.decode('ascii', 'replace').rstrip()
        self.assertEqual(out, 'mbcs replace')


@test.support.cpython_only
class UnraisableHookTest(unittest.TestCase):
    def write_unraisable_exc(self, exc, err_msg, obj):
        import _testcapi
        import types
        err_msg2 = f"Exception ignored {err_msg}"
        try:
            _testcapi.write_unraisable_exc(exc, err_msg, obj)
            return types.SimpleNamespace(exc_type=type(exc),
                                         exc_value=exc,
                                         exc_traceback=exc.__traceback__,
                                         err_msg=err_msg2,
                                         object=obj)
        finally:
            # Explicitly break any reference cycle
            exc = None

    def test_original_unraisablehook(self):
        for err_msg in (None, "original hook"):
            with self.subTest(err_msg=err_msg):
                obj = "an object"

                with test.support.captured_output("stderr") as stderr:
                    with test.support.swap_attr(sys, 'unraisablehook',
                                                sys.__unraisablehook__):
                        self.write_unraisable_exc(ValueError(42), err_msg, obj)

                err = stderr.getvalue()
                if err_msg is not None:
                    self.assertIn(f'Exception ignored {err_msg}: {obj!r}\n', err)
                else:
                    self.assertIn(f'Exception ignored in: {obj!r}\n', err)
                self.assertIn('Traceback (most recent call last):\n', err)
                self.assertIn('ValueError: 42\n', err)

    def test_original_unraisablehook_err(self):
        # bpo-22836: PyErr_WriteUnraisable() should give sensible reports
        class BrokenDel:
            def __del__(self):
                exc = ValueError("del is broken")
                # The following line is included in the traceback report:
                raise exc

        class BrokenStrException(Exception):
            def __str__(self):
                raise Exception("str() is broken")

        class BrokenExceptionDel:
            def __del__(self):
                exc = BrokenStrException()
                # The following line is included in the traceback report:
                raise exc

        for test_class in (BrokenDel, BrokenExceptionDel):
            with self.subTest(test_class):
                obj = test_class()
                with test.support.captured_stderr() as stderr, \
                     test.support.swap_attr(sys, 'unraisablehook',
                                            sys.__unraisablehook__):
                    # Trigger obj.__del__()
                    del obj

                report = stderr.getvalue()
                self.assertIn("Exception ignored", report)
                self.assertIn(test_class.__del__.__qualname__, report)
                self.assertIn("test_sys.py", report)
                self.assertIn("raise exc", report)
                if test_class is BrokenExceptionDel:
                    self.assertIn("BrokenStrException", report)
                    self.assertIn("<exception str() failed>", report)
                else:
                    self.assertIn("ValueError", report)
                    self.assertIn("del is broken", report)
                self.assertTrue(report.endswith("\n"))


    def test_original_unraisablehook_wrong_type(self):
        exc = ValueError(42)
        with test.support.swap_attr(sys, 'unraisablehook',
                                    sys.__unraisablehook__):
            with self.assertRaises(TypeError):
                sys.unraisablehook(exc)

    def test_custom_unraisablehook(self):
        hook_args = None

        def hook_func(args):
            nonlocal hook_args
            hook_args = args

        obj = object()
        try:
            with test.support.swap_attr(sys, 'unraisablehook', hook_func):
                expected = self.write_unraisable_exc(ValueError(42),
                                                     "custom hook", obj)
                for attr in "exc_type exc_value exc_traceback err_msg object".split():
                    self.assertEqual(getattr(hook_args, attr),
                                     getattr(expected, attr),
                                     (hook_args, expected))
        finally:
            # expected and hook_args contain an exception: break reference cycle
            expected = None
            hook_args = None

    def test_custom_unraisablehook_fail(self):
        def hook_func(*args):
            raise Exception("hook_func failed")

        with test.support.captured_output("stderr") as stderr:
            with test.support.swap_attr(sys, 'unraisablehook', hook_func):
                self.write_unraisable_exc(ValueError(42),
                                          "custom hook fail", None)

        err = stderr.getvalue()
        self.assertIn(f'Exception ignored in sys.unraisablehook: '
                      f'{hook_func!r}\n',
                      err)
        self.assertIn('Traceback (most recent call last):\n', err)
        self.assertIn('Exception: hook_func failed\n', err)


@test.support.cpython_only
class SizeofTest(unittest.TestCase):

    def setUp(self):
        self.P = struct.calcsize('P')
        self.longdigit = sys.int_info.sizeof_digit
        import _testcapi
        self.gc_headsize = _testcapi.SIZEOF_PYGC_HEAD

    check_sizeof = test.support.check_sizeof

    def test_gc_head_size(self):
        # Check that the gc header size is added to objects tracked by the gc.
        vsize = test.support.calcvobjsize
        gc_header_size = self.gc_headsize
        # bool objects are not gc tracked
        self.assertEqual(sys.getsizeof(True), vsize('') + self.longdigit)
        # but lists are
        self.assertEqual(sys.getsizeof([]), vsize('Pn') + gc_header_size)

    def test_errors(self):
        class BadSizeof:
            def __sizeof__(self):
                raise ValueError
        self.assertRaises(ValueError, sys.getsizeof, BadSizeof())

        class InvalidSizeof:
            def __sizeof__(self):
                return None
        self.assertRaises(TypeError, sys.getsizeof, InvalidSizeof())
        sentinel = ["sentinel"]
        self.assertIs(sys.getsizeof(InvalidSizeof(), sentinel), sentinel)

        class FloatSizeof:
            def __sizeof__(self):
                return 4.5
        self.assertRaises(TypeError, sys.getsizeof, FloatSizeof())
        self.assertIs(sys.getsizeof(FloatSizeof(), sentinel), sentinel)

        class OverflowSizeof(int):
            def __sizeof__(self):
                return int(self)
        self.assertEqual(sys.getsizeof(OverflowSizeof(sys.maxsize)),
                         sys.maxsize + self.gc_headsize)
        with self.assertRaises(OverflowError):
            sys.getsizeof(OverflowSizeof(sys.maxsize + 1))
        with self.assertRaises(ValueError):
            sys.getsizeof(OverflowSizeof(-1))
        with self.assertRaises((ValueError, OverflowError)):
            sys.getsizeof(OverflowSizeof(-sys.maxsize - 1))

    def test_default(self):
        size = test.support.calcvobjsize
        self.assertEqual(sys.getsizeof(True), size('') + self.longdigit)
        self.assertEqual(sys.getsizeof(True, -1), size('') + self.longdigit)

    def test_objecttypes(self):
        # check all types defined in Objects/
        calcsize = struct.calcsize
        size = test.support.calcobjsize
        vsize = test.support.calcvobjsize
        check = self.check_sizeof
        # bool
        check(True, vsize('') + self.longdigit)
        # buffer
        # XXX
        # builtin_function_or_method
        check(len, size('5P'))
        # bytearray
        samples = [b'', b'u'*100000]
        for sample in samples:
            x = bytearray(sample)
            check(x, vsize('n2Pi') + x.__alloc__())
        # bytearray_iterator
        check(iter(bytearray()), size('nP'))
        # bytes
        check(b'', vsize('n') + 1)
        check(b'x' * 10, vsize('n') + 11)
        # cell
        def get_cell():
            x = 42
            def inner():
                return x
            return inner
        check(get_cell().__closure__[0], size('P'))
        # code
        def check_code_size(a, expected_size):
            self.assertGreaterEqual(sys.getsizeof(a), expected_size)
        check_code_size(get_cell().__code__, size('6i13P'))
        check_code_size(get_cell.__code__, size('6i13P'))
        def get_cell2(x):
            def inner():
                return x
            return inner
        check_code_size(get_cell2.__code__, size('6i13P') + calcsize('n'))
        # complex
        check(complex(0,1), size('2d'))
        # method_descriptor (descriptor object)
        check(str.lower, size('3PPP'))
        # classmethod_descriptor (descriptor object)
        # XXX
        # member_descriptor (descriptor object)
        import datetime
        check(datetime.timedelta.days, size('3PP'))
        # getset_descriptor (descriptor object)
        import collections
        check(collections.defaultdict.default_factory, size('3PP'))
        # wrapper_descriptor (descriptor object)
        check(int.__add__, size('3P2P'))
        # method-wrapper (descriptor object)
        check({}.__iter__, size('2P'))
        # empty dict
        check({}, size('nQ2P'))
        # dict
        check({"a": 1}, size('nQ2P') + calcsize('2nP2n') + 8 + (8*2//3)*calcsize('n2P'))
        longdict = {1:1, 2:2, 3:3, 4:4, 5:5, 6:6, 7:7, 8:8}
        check(longdict, size('nQ2P') + calcsize('2nP2n') + 16 + (16*2//3)*calcsize('n2P'))
        # dictionary-keyview
        check({}.keys(), size('P'))
        # dictionary-valueview
        check({}.values(), size('P'))
        # dictionary-itemview
        check({}.items(), size('P'))
        # dictionary iterator
        check(iter({}), size('P2nPn'))
        # dictionary-keyiterator
        check(iter({}.keys()), size('P2nPn'))
        # dictionary-valueiterator
        check(iter({}.values()), size('P2nPn'))
        # dictionary-itemiterator
        check(iter({}.items()), size('P2nPn'))
        # dictproxy
        class C(object): pass
        check(C.__dict__, size('P'))
        # BaseException
        check(BaseException(), size('5Pb'))
        # UnicodeEncodeError
        check(UnicodeEncodeError("", "", 0, 0, ""), size('5Pb 2P2nP'))
        # UnicodeDecodeError
        check(UnicodeDecodeError("", b"", 0, 0, ""), size('5Pb 2P2nP'))
        # UnicodeTranslateError
        check(UnicodeTranslateError("", 0, 1, ""), size('5Pb 2P2nP'))
        # ellipses
        check(Ellipsis, size(''))
        # EncodingMap
        import codecs, encodings.iso8859_3
        x = codecs.charmap_build(encodings.iso8859_3.decoding_table)
        check(x, size('32B2iB'))
        # enumerate
        check(enumerate([]), size('n3P'))
        # reverse
        check(reversed(''), size('nP'))
        # float
        check(float(0), size('d'))
        # sys.floatinfo
        check(sys.float_info, vsize('') + self.P * len(sys.float_info))
        # frame
        import inspect
        CO_MAXBLOCKS = 20
        x = inspect.currentframe()
        ncells = len(x.f_code.co_cellvars)
        nfrees = len(x.f_code.co_freevars)
        extras = x.f_code.co_stacksize + x.f_code.co_nlocals +\
                  ncells + nfrees - 1
        check(x, vsize('5P2c4P3ic' + CO_MAXBLOCKS*'3i' + 'P' + extras*'P'))
        # function
        def func(): pass
        check(func, size('13P'))
        class c():
            @staticmethod
            def foo():
                pass
            @classmethod
            def bar(cls):
                pass
            # staticmethod
            check(foo, size('PP'))
            # classmethod
            check(bar, size('PP'))
        # generator
        def get_gen(): yield 1
        check(get_gen(), size('Pb2PPP4P'))
        # iterator
        check(iter('abc'), size('lP'))
        # callable-iterator
        import re
        check(re.finditer('',''), size('2P'))
        # list
        samples = [[], [1,2,3], ['1', '2', '3']]
        for sample in samples:
            check(sample, vsize('Pn') + len(sample)*self.P)
        # sortwrapper (list)
        # XXX
        # cmpwrapper (list)
        # XXX
        # listiterator (list)
        check(iter([]), size('lP'))
        # listreverseiterator (list)
        check(reversed([]), size('nP'))
        # int
        check(0, vsize(''))
        check(1, vsize('') + self.longdigit)
        check(-1, vsize('') + self.longdigit)
        PyLong_BASE = 2**sys.int_info.bits_per_digit
        check(int(PyLong_BASE), vsize('') + 2*self.longdigit)
        check(int(PyLong_BASE**2-1), vsize('') + 2*self.longdigit)
        check(int(PyLong_BASE**2), vsize('') + 3*self.longdigit)
        # module
        check(unittest, size('PnPPP'))
        # None
        check(None, size(''))
        # NotImplementedType
        check(NotImplemented, size(''))
        # object
        check(object(), size(''))
        # property (descriptor object)
        class C(object):
            def getx(self): return self.__x
            def setx(self, value): self.__x = value
            def delx(self): del self.__x
            x = property(getx, setx, delx, "")
            check(x, size('4Pi'))
        # PyCapsule
        # XXX
        # rangeiterator
        check(iter(range(1)), size('4l'))
        # reverse
        check(reversed(''), size('nP'))
        # range
        check(range(1), size('4P'))
        check(range(66000), size('4P'))
        # set
        # frozenset
        PySet_MINSIZE = 8
        samples = [[], range(10), range(50)]
        s = size('3nP' + PySet_MINSIZE*'nP' + '2nP')
        for sample in samples:
            minused = len(sample)
            if minused == 0: tmp = 1
            # the computation of minused is actually a bit more complicated
            # but this suffices for the sizeof test
            minused = minused*2
            newsize = PySet_MINSIZE
            while newsize <= minused:
                newsize = newsize << 1
            if newsize <= 8:
                check(set(sample), s)
                check(frozenset(sample), s)
            else:
                check(set(sample), s + newsize*calcsize('nP'))
                check(frozenset(sample), s + newsize*calcsize('nP'))
        # setiterator
        check(iter(set()), size('P3n'))
        # slice
        check(slice(0), size('3P'))
        # super
        check(super(int), size('3P'))
        # tuple
        check((), vsize(''))
        check((1,2,3), vsize('') + 3*self.P)
        # type
        # static type: PyTypeObject
        fmt = 'P2nPI13Pl4Pn9Pn11PIPP'
        if hasattr(sys, 'getcounts'):
            fmt += '3n2P'
        s = vsize(fmt)
        check(int, s)
        # class
        s = vsize(fmt +                 # PyTypeObject
                  '3P'                  # PyAsyncMethods
                  '36P'                 # PyNumberMethods
                  '3P'                  # PyMappingMethods
                  '10P'                 # PySequenceMethods
                  '2P'                  # PyBufferProcs
                  '4P')
        class newstyleclass(object): pass
        # Separate block for PyDictKeysObject with 8 keys and 5 entries
        check(newstyleclass, s + calcsize("2nP2n0P") + 8 + 5*calcsize("n2P"))
        # dict with shared keys
        check(newstyleclass().__dict__, size('nQ2P') + 5*self.P)
        o = newstyleclass()
        o.a = o.b = o.c = o.d = o.e = o.f = o.g = o.h = 1
        # Separate block for PyDictKeysObject with 16 keys and 10 entries
        check(newstyleclass, s + calcsize("2nP2n0P") + 16 + 10*calcsize("n2P"))
        # dict with shared keys
        check(newstyleclass().__dict__, size('nQ2P') + 10*self.P)
        # unicode
        # each tuple contains a string and its expected character size
        # don't put any static strings here, as they may contain
        # wchar_t or UTF-8 representations
        samples = ['1'*100, '\xff'*50,
                   '\u0100'*40, '\uffff'*100,
                   '\U00010000'*30, '\U0010ffff'*100]
        asciifields = "nnbP"
        compactfields = asciifields + "nPn"
        unicodefields = compactfields + "P"
        for s in samples:
            maxchar = ord(max(s))
            if maxchar < 128:
                L = size(asciifields) + len(s) + 1
            elif maxchar < 256:
                L = size(compactfields) + len(s) + 1
            elif maxchar < 65536:
                L = size(compactfields) + 2*(len(s) + 1)
            else:
                L = size(compactfields) + 4*(len(s) + 1)
            check(s, L)
        # verify that the UTF-8 size is accounted for
        s = chr(0x4000)   # 4 bytes canonical representation
        check(s, size(compactfields) + 4)
        # compile() will trigger the generation of the UTF-8
        # representation as a side effect
        compile(s, "<stdin>", "eval")
        check(s, size(compactfields) + 4 + 4)
        # TODO: add check that forces the presence of wchar_t representation
        # TODO: add check that forces layout of unicodefields
        # weakref
        import weakref
        check(weakref.ref(int), size('2Pn2P'))
        # weakproxy
        # XXX
        # weakcallableproxy
        check(weakref.proxy(int), size('2Pn2P'))

    def check_slots(self, obj, base, extra):
        expected = sys.getsizeof(base) + struct.calcsize(extra)
        if gc.is_tracked(obj) and not gc.is_tracked(base):
            expected += self.gc_headsize
        self.assertEqual(sys.getsizeof(obj), expected)

    def test_slots(self):
        # check all subclassable types defined in Objects/ that allow
        # non-empty __slots__
        check = self.check_slots
        class BA(bytearray):
            __slots__ = 'a', 'b', 'c'
        check(BA(), bytearray(), '3P')
        class D(dict):
            __slots__ = 'a', 'b', 'c'
        check(D(x=[]), {'x': []}, '3P')
        class L(list):
            __slots__ = 'a', 'b', 'c'
        check(L(), [], '3P')
        class S(set):
            __slots__ = 'a', 'b', 'c'
        check(S(), set(), '3P')
        class FS(frozenset):
            __slots__ = 'a', 'b', 'c'
        check(FS(), frozenset(), '3P')
        from collections import OrderedDict
        class OD(OrderedDict):
            __slots__ = 'a', 'b', 'c'
        check(OD(x=[]), OrderedDict(x=[]), '3P')

    def test_pythontypes(self):
        # check all types defined in Python/
        size = test.support.calcobjsize
        vsize = test.support.calcvobjsize
        check = self.check_sizeof
        # _ast.AST
        import _ast
        check(_ast.AST(), size('P'))
        try:
            raise TypeError
        except TypeError:
            tb = sys.exc_info()[2]
            # traceback
            if tb is not None:
                check(tb, size('2P2i'))
        # symtable entry
        # XXX
        # sys.flags
        check(sys.flags, vsize('') + self.P * len(sys.flags))

    def test_asyncgen_hooks(self):
        old = sys.get_asyncgen_hooks()
        self.assertIsNone(old.firstiter)
        self.assertIsNone(old.finalizer)

        firstiter = lambda *a: None
        sys.set_asyncgen_hooks(firstiter=firstiter)
        hooks = sys.get_asyncgen_hooks()
        self.assertIs(hooks.firstiter, firstiter)
        self.assertIs(hooks[0], firstiter)
        self.assertIs(hooks.finalizer, None)
        self.assertIs(hooks[1], None)

        finalizer = lambda *a: None
        sys.set_asyncgen_hooks(finalizer=finalizer)
        hooks = sys.get_asyncgen_hooks()
        self.assertIs(hooks.firstiter, firstiter)
        self.assertIs(hooks[0], firstiter)
        self.assertIs(hooks.finalizer, finalizer)
        self.assertIs(hooks[1], finalizer)

        sys.set_asyncgen_hooks(*old)
        cur = sys.get_asyncgen_hooks()
        self.assertIsNone(cur.firstiter)
        self.assertIsNone(cur.finalizer)


if __name__ == "__main__":
    unittest.main()