text: # As a test suite for the os module, this is woefully inadequate, but this
  # does add tests for a few functions which have been determined to be more
  # portable than they had been thought to be.
  
  import asynchat
  import asyncore
  import codecs
  import contextlib
  import decimal
  import errno
  import fnmatch
  import fractions
  import itertools
  import locale
  import mmap
  import os
  import pickle
  import shutil
  import signal
  import socket
  import stat
  import subprocess
  import sys
  import sysconfig
  import tempfile
  import threading
  import time
  import unittest
  import uuid
  import warnings
  from test import support
  from platform import win32_is_iot
  
  try:
      import resource
  except ImportError:
      resource = None
  try:
      import fcntl
  except ImportError:
      fcntl = None
  try:
      import _winapi
  except ImportError:
      _winapi = None
  try:
      import pwd
      all_users = [u.pw_uid for u in pwd.getpwall()]
  except (ImportError, AttributeError):
      all_users = []
  try:
      from _testcapi import INT_MAX, PY_SSIZE_T_MAX
  except ImportError:
      INT_MAX = PY_SSIZE_T_MAX = sys.maxsize
  
  from test.support.script_helper import assert_python_ok
  from test.support import unix_shell, FakePath
  
  
  root_in_posix = False
  if hasattr(os, 'geteuid'):
      root_in_posix = (os.geteuid() == 0)
  
  # Detect whether we're on a Linux system that uses the (now outdated
  # and unmaintained) linuxthreads threading library.  There's an issue
  # when combining linuxthreads with a failed execv call: see
  # http://bugs.python.org/issue4970.
  if hasattr(sys, 'thread_info') and sys.thread_info.version:
      USING_LINUXTHREADS = sys.thread_info.version.startswith("linuxthreads")
  else:
      USING_LINUXTHREADS = False
  
  # Issue #14110: Some tests fail on FreeBSD if the user is in the wheel group.
  HAVE_WHEEL_GROUP = sys.platform.startswith('freebsd') and os.getgid() == 0
  
  
  def requires_os_func(name):
      return unittest.skipUnless(hasattr(os, name), 'requires os.%s' % name)
  
  
  def create_file(filename, content=b'content'):
      with open(filename, "xb", 0) as fp:
          fp.write(content)
  
  
  class MiscTests(unittest.TestCase):
      def test_getcwd(self):
          cwd = os.getcwd()
          self.assertIsInstance(cwd, str)
  
      def test_getcwd_long_path(self):
          # bpo-37412: On Linux, PATH_MAX is usually around 4096 bytes. On
          # Windows, MAX_PATH is defined as 260 characters, but Windows supports
          # longer path if longer paths support is enabled. Internally, the os
          # module uses MAXPATHLEN which is at least 1024.
          #
          # Use a directory name of 200 characters to fit into Windows MAX_PATH
          # limit.
          #
          # On Windows, the test can stop when trying to create a path longer
          # than MAX_PATH if long paths support is disabled:
          # see RtlAreLongPathsEnabled().
          min_len = 2000   # characters
          dirlen = 200     # characters
          dirname = 'python_test_dir_'
          dirname = dirname + ('a' * (dirlen - len(dirname)))
  
          with tempfile.TemporaryDirectory() as tmpdir:
              with support.change_cwd(tmpdir) as path:
                  expected = path
  
                  while True:
                      cwd = os.getcwd()
                      self.assertEqual(cwd, expected)
  
                      need = min_len - (len(cwd) + len(os.path.sep))
                      if need <= 0:
                          break
                      if len(dirname) > need and need > 0:
                          dirname = dirname[:need]
  
                      path = os.path.join(path, dirname)
                      try:
                          os.mkdir(path)
                          # On Windows, chdir() can fail
                          # even if mkdir() succeeded
                          os.chdir(path)
                      except FileNotFoundError:
                          # On Windows, catch ERROR_PATH_NOT_FOUND (3) and
                          # ERROR_FILENAME_EXCED_RANGE (206) errors
                          # ("The filename or extension is too long")
                          break
                      except OSError as exc:
                          if exc.errno == errno.ENAMETOOLONG:
                              break
                          else:
                              raise
  
                      expected = path
  
                  if support.verbose:
                      print(f"Tested current directory length: {len(cwd)}")
  
      def test_getcwdb(self):
          cwd = os.getcwdb()
          self.assertIsInstance(cwd, bytes)
          self.assertEqual(os.fsdecode(cwd), os.getcwd())
  
  
  # Tests creating TESTFN
  class FileTests(unittest.TestCase):
      def setUp(self):
          if os.path.lexists(support.TESTFN):
              os.unlink(support.TESTFN)
      tearDown = setUp
  
      def test_access(self):
          f = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
          os.close(f)
          self.assertTrue(os.access(support.TESTFN, os.W_OK))
  
      def test_closerange(self):
          first = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
          # We must allocate two consecutive file descriptors, otherwise
          # it will mess up other file descriptors (perhaps even the three
          # standard ones).
          second = os.dup(first)
          try:
              retries = 0
              while second != first + 1:
                  os.close(first)
                  retries += 1
                  if retries > 10:
                      # XXX test skipped
                      self.skipTest("couldn't allocate two consecutive fds")
                  first, second = second, os.dup(second)
          finally:
              os.close(second)
          # close a fd that is open, and one that isn't
          os.closerange(first, first + 2)
          self.assertRaises(OSError, os.write, first, b"a")
  
      @support.cpython_only
      def test_rename(self):
          path = support.TESTFN
          old = sys.getrefcount(path)
          self.assertRaises(TypeError, os.rename, path, 0)
          new = sys.getrefcount(path)
          self.assertEqual(old, new)
  
      def test_read(self):
          with open(support.TESTFN, "w+b") as fobj:
              fobj.write(b"spam")
              fobj.flush()
              fd = fobj.fileno()
              os.lseek(fd, 0, 0)
              s = os.read(fd, 4)
              self.assertEqual(type(s), bytes)
              self.assertEqual(s, b"spam")
  
      @support.cpython_only
      # Skip the test on 32-bit platforms: the number of bytes must fit in a
      # Py_ssize_t type
      @unittest.skipUnless(INT_MAX < PY_SSIZE_T_MAX,
                           "needs INT_MAX < PY_SSIZE_T_MAX")
      @support.bigmemtest(size=INT_MAX + 10, memuse=1, dry_run=False)
      def test_large_read(self, size):
          self.addCleanup(support.unlink, support.TESTFN)
          create_file(support.TESTFN, b'test')
  
          # Issue #21932: Make sure that os.read() does not raise an
          # OverflowError for size larger than INT_MAX
          with open(support.TESTFN, "rb") as fp:
              data = os.read(fp.fileno(), size)
  
          # The test does not try to read more than 2 GiB at once because the
          # operating system is free to return less bytes than requested.
          self.assertEqual(data, b'test')
  
      def test_write(self):
          # os.write() accepts bytes- and buffer-like objects but not strings
          fd = os.open(support.TESTFN, os.O_CREAT | os.O_WRONLY)
          self.assertRaises(TypeError, os.write, fd, "beans")
          os.write(fd, b"bacon\n")
          os.write(fd, bytearray(b"eggs\n"))
          os.write(fd, memoryview(b"spam\n"))
          os.close(fd)
          with open(support.TESTFN, "rb") as fobj:
              self.assertEqual(fobj.read().splitlines(),
                  [b"bacon", b"eggs", b"spam"])
  
      def write_windows_console(self, *args):
          retcode = subprocess.call(args,
              # use a new console to not flood the test output
              creationflags=subprocess.CREATE_NEW_CONSOLE,
              # use a shell to hide the console window (SW_HIDE)
              shell=True)
          self.assertEqual(retcode, 0)
  
      @unittest.skipUnless(sys.platform == 'win32',
                           'test specific to the Windows console')
      def test_write_windows_console(self):
          # Issue #11395: the Windows console returns an error (12: not enough
          # space error) on writing into stdout if stdout mode is binary and the
          # length is greater than 66,000 bytes (or less, depending on heap
          # usage).
          code = "print('x' * 100000)"
          self.write_windows_console(sys.executable, "-c", code)
          self.write_windows_console(sys.executable, "-u", "-c", code)
  
      def fdopen_helper(self, *args):
          fd = os.open(support.TESTFN, os.O_RDONLY)
          f = os.fdopen(fd, *args)
          f.close()
  
      def test_fdopen(self):
          fd = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
          os.close(fd)
  
          self.fdopen_helper()
          self.fdopen_helper('r')
          self.fdopen_helper('r', 100)
  
      def test_replace(self):
          TESTFN2 = support.TESTFN + ".2"
          self.addCleanup(support.unlink, support.TESTFN)
          self.addCleanup(support.unlink, TESTFN2)
  
          create_file(support.TESTFN, b"1")
          create_file(TESTFN2, b"2")
  
          os.replace(support.TESTFN, TESTFN2)
          self.assertRaises(FileNotFoundError, os.stat, support.TESTFN)
          with open(TESTFN2, 'r') as f:
              self.assertEqual(f.read(), "1")
  
      def test_open_keywords(self):
          f = os.open(path=__file__, flags=os.O_RDONLY, mode=0o777,
              dir_fd=None)
          os.close(f)
  
      def test_symlink_keywords(self):
          symlink = support.get_attribute(os, "symlink")
          try:
              symlink(src='target', dst=support.TESTFN,
                  target_is_directory=False, dir_fd=None)
          except (NotImplementedError, OSError):
              pass  # No OS support or unprivileged user
  
      @unittest.skipUnless(hasattr(os, 'copy_file_range'), 'test needs os.copy_file_range()')
      def test_copy_file_range_invalid_values(self):
          with self.assertRaises(ValueError):
              os.copy_file_range(0, 1, -10)
  
      @unittest.skipUnless(hasattr(os, 'copy_file_range'), 'test needs os.copy_file_range()')
      def test_copy_file_range(self):
          TESTFN2 = support.TESTFN + ".3"
          data = b'0123456789'
  
          create_file(support.TESTFN, data)
          self.addCleanup(support.unlink, support.TESTFN)
  
          in_file = open(support.TESTFN, 'rb')
          self.addCleanup(in_file.close)
          in_fd = in_file.fileno()
  
          out_file = open(TESTFN2, 'w+b')
          self.addCleanup(support.unlink, TESTFN2)
          self.addCleanup(out_file.close)
          out_fd = out_file.fileno()
  
          try:
              i = os.copy_file_range(in_fd, out_fd, 5)
          except OSError as e:
              # Handle the case in which Python was compiled
              # in a system with the syscall but without support
              # in the kernel.
              if e.errno != errno.ENOSYS:
                  raise
              self.skipTest(e)
          else:
              # The number of copied bytes can be less than
              # the number of bytes originally requested.
              self.assertIn(i, range(0, 6));
  
              with open(TESTFN2, 'rb') as in_file:
                  self.assertEqual(in_file.read(), data[:i])
  
      @unittest.skipUnless(hasattr(os, 'copy_file_range'), 'test needs os.copy_file_range()')
      def test_copy_file_range_offset(self):
          TESTFN4 = support.TESTFN + ".4"
          data = b'0123456789'
          bytes_to_copy = 6
          in_skip = 3
          out_seek = 5
  
          create_file(support.TESTFN, data)
          self.addCleanup(support.unlink, support.TESTFN)
  
          in_file = open(support.TESTFN, 'rb')
          self.addCleanup(in_file.close)
          in_fd = in_file.fileno()
  
          out_file = open(TESTFN4, 'w+b')
          self.addCleanup(support.unlink, TESTFN4)
          self.addCleanup(out_file.close)
          out_fd = out_file.fileno()
  
          try:
              i = os.copy_file_range(in_fd, out_fd, bytes_to_copy,
                                     offset_src=in_skip,
                                     offset_dst=out_seek)
          except OSError as e:
              # Handle the case in which Python was compiled
              # in a system with the syscall but without support
              # in the kernel.
              if e.errno != errno.ENOSYS:
                  raise
              self.skipTest(e)
          else:
              # The number of copied bytes can be less than
              # the number of bytes originally requested.
              self.assertIn(i, range(0, bytes_to_copy+1));
  
              with open(TESTFN4, 'rb') as in_file:
                  read = in_file.read()
              # seeked bytes (5) are zero'ed
              self.assertEqual(read[:out_seek], b'\x00'*out_seek)
              # 012 are skipped (in_skip)
              # 345678 are copied in the file (in_skip + bytes_to_copy)
              self.assertEqual(read[out_seek:],
                               data[in_skip:in_skip+i])
  
  # Test attributes on return values from os.*stat* family.
  class StatAttributeTests(unittest.TestCase):
      def setUp(self):
          self.fname = support.TESTFN
          self.addCleanup(support.unlink, self.fname)
          create_file(self.fname, b"ABC")
  
      def check_stat_attributes(self, fname):
          result = os.stat(fname)
  
          # Make sure direct access works
          self.assertEqual(result[stat.ST_SIZE], 3)
          self.assertEqual(result.st_size, 3)
  
          # Make sure all the attributes are there
          members = dir(result)
          for name in dir(stat):
              if name[:3] == 'ST_':
                  attr = name.lower()
                  if name.endswith("TIME"):
                      def trunc(x): return int(x)
                  else:
                      def trunc(x): return x
                  self.assertEqual(trunc(getattr(result, attr)),
                                    result[getattr(stat, name)])
                  self.assertIn(attr, members)
  
          # Make sure that the st_?time and st_?time_ns fields roughly agree
          # (they should always agree up to around tens-of-microseconds)
          for name in 'st_atime st_mtime st_ctime'.split():
              floaty = int(getattr(result, name) * 100000)
              nanosecondy = getattr(result, name + "_ns") // 10000
              self.assertAlmostEqual(floaty, nanosecondy, delta=2)
  
          try:
              result[200]
              self.fail("No exception raised")
          except IndexError:
              pass
  
          # Make sure that assignment fails
          try:
              result.st_mode = 1
              self.fail("No exception raised")
          except AttributeError:
              pass
  
          try:
              result.st_rdev = 1
              self.fail("No exception raised")
          except (AttributeError, TypeError):
              pass
  
          try:
              result.parrot = 1
              self.fail("No exception raised")
          except AttributeError:
              pass
  
          # Use the stat_result constructor with a too-short tuple.
          try:
              result2 = os.stat_result((10,))
              self.fail("No exception raised")
          except TypeError:
              pass
  
          # Use the constructor with a too-long tuple.
          try:
              result2 = os.stat_result((0,1,2,3,4,5,6,7,8,9,10,11,12,13,14))
          except TypeError:
              pass
  
      def test_stat_attributes(self):
          self.check_stat_attributes(self.fname)
  
      def test_stat_attributes_bytes(self):
          try:
              fname = self.fname.encode(sys.getfilesystemencoding())
          except UnicodeEncodeError:
              self.skipTest("cannot encode %a for the filesystem" % self.fname)
          self.check_stat_attributes(fname)
  
      def test_stat_result_pickle(self):
          result = os.stat(self.fname)
          for proto in range(pickle.HIGHEST_PROTOCOL + 1):
              p = pickle.dumps(result, proto)
              self.assertIn(b'stat_result', p)
              if proto < 4:
                  self.assertIn(b'cos\nstat_result\n', p)
              unpickled = pickle.loads(p)
              self.assertEqual(result, unpickled)
  
      @unittest.skipUnless(hasattr(os, 'statvfs'), 'test needs os.statvfs()')
      def test_statvfs_attributes(self):
          result = os.statvfs(self.fname)
  
          # Make sure direct access works
          self.assertEqual(result.f_bfree, result[3])
  
          # Make sure all the attributes are there.
          members = ('bsize', 'frsize', 'blocks', 'bfree', 'bavail', 'files',
                      'ffree', 'favail', 'flag', 'namemax')
          for value, member in enumerate(members):
              self.assertEqual(getattr(result, 'f_' + member), result[value])
  
          self.assertTrue(isinstance(result.f_fsid, int))
  
          # Test that the size of the tuple doesn't change
          self.assertEqual(len(result), 10)
  
          # Make sure that assignment really fails
          try:
              result.f_bfree = 1
              self.fail("No exception raised")
          except AttributeError:
              pass
  
          try:
              result.parrot = 1
              self.fail("No exception raised")
          except AttributeError:
              pass
  
          # Use the constructor with a too-short tuple.
          try:
              result2 = os.statvfs_result((10,))
              self.fail("No exception raised")
          except TypeError:
              pass
  
          # Use the constructor with a too-long tuple.
          try:
              result2 = os.statvfs_result((0,1,2,3,4,5,6,7,8,9,10,11,12,13,14))
          except TypeError:
              pass
  
      @unittest.skipUnless(hasattr(os, 'statvfs'),
                           "need os.statvfs()")
      def test_statvfs_result_pickle(self):
          result = os.statvfs(self.fname)
  
          for proto in range(pickle.HIGHEST_PROTOCOL + 1):
              p = pickle.dumps(result, proto)
              self.assertIn(b'statvfs_result', p)
              if proto < 4:
                  self.assertIn(b'cos\nstatvfs_result\n', p)
              unpickled = pickle.loads(p)
              self.assertEqual(result, unpickled)
  
      @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
      def test_1686475(self):
          # Verify that an open file can be stat'ed
          try:
              os.stat(r"c:\pagefile.sys")
          except FileNotFoundError:
              self.skipTest(r'c:\pagefile.sys does not exist')
          except OSError as e:
              self.fail("Could not stat pagefile.sys")
  
      @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
      @unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
      def test_15261(self):
          # Verify that stat'ing a closed fd does not cause crash
          r, w = os.pipe()
          try:
              os.stat(r)          # should not raise error
          finally:
              os.close(r)
              os.close(w)
          with self.assertRaises(OSError) as ctx:
              os.stat(r)
          self.assertEqual(ctx.exception.errno, errno.EBADF)
  
      def check_file_attributes(self, result):
          self.assertTrue(hasattr(result, 'st_file_attributes'))
          self.assertTrue(isinstance(result.st_file_attributes, int))
          self.assertTrue(0 <= result.st_file_attributes <= 0xFFFFFFFF)
  
      @unittest.skipUnless(sys.platform == "win32",
                           "st_file_attributes is Win32 specific")
      def test_file_attributes(self):
          # test file st_file_attributes (FILE_ATTRIBUTE_DIRECTORY not set)
          result = os.stat(self.fname)
          self.check_file_attributes(result)
          self.assertEqual(
              result.st_file_attributes & stat.FILE_ATTRIBUTE_DIRECTORY,
              0)
  
          # test directory st_file_attributes (FILE_ATTRIBUTE_DIRECTORY set)
          dirname = support.TESTFN + "dir"
          os.mkdir(dirname)
          self.addCleanup(os.rmdir, dirname)
  
          result = os.stat(dirname)
          self.check_file_attributes(result)
          self.assertEqual(
              result.st_file_attributes & stat.FILE_ATTRIBUTE_DIRECTORY,
              stat.FILE_ATTRIBUTE_DIRECTORY)
  
      @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
      def test_access_denied(self):
          # Default to FindFirstFile WIN32_FIND_DATA when access is
          # denied. See issue 28075.
          # os.environ['TEMP'] should be located on a volume that
          # supports file ACLs.
          fname = os.path.join(os.environ['TEMP'], self.fname)
          self.addCleanup(support.unlink, fname)
          create_file(fname, b'ABC')
          # Deny the right to [S]YNCHRONIZE on the file to
          # force CreateFile to fail with ERROR_ACCESS_DENIED.
          DETACHED_PROCESS = 8
          subprocess.check_call(
              # bpo-30584: Use security identifier *S-1-5-32-545 instead
              # of localized "Users" to not depend on the locale.
              ['icacls.exe', fname, '/deny', '*S-1-5-32-545:(S)'],
              creationflags=DETACHED_PROCESS
          )
          result = os.stat(fname)
          self.assertNotEqual(result.st_size, 0)
  
      @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
      def test_stat_block_device(self):
          # bpo-38030: os.stat fails for block devices
          # Test a filename like "//./C:"
          fname = "//./" + os.path.splitdrive(os.getcwd())[0]
          result = os.stat(fname)
          self.assertEqual(result.st_mode, stat.S_IFBLK)
  
  
  class UtimeTests(unittest.TestCase):
      def setUp(self):
          self.dirname = support.TESTFN
          self.fname = os.path.join(self.dirname, "f1")
  
          self.addCleanup(support.rmtree, self.dirname)
          os.mkdir(self.dirname)
          create_file(self.fname)
  
      def support_subsecond(self, filename):
          # Heuristic to check if the filesystem supports timestamp with
          # subsecond resolution: check if float and int timestamps are different
          st = os.stat(filename)
          return ((st.st_atime != st[7])
                  or (st.st_mtime != st[8])
                  or (st.st_ctime != st[9]))
  
      def _test_utime(self, set_time, filename=None):
          if not filename:
              filename = self.fname
  
          support_subsecond = self.support_subsecond(filename)
          if support_subsecond:
              # Timestamp with a resolution of 1 microsecond (10^-6).
              #
              # The resolution of the C internal function used by os.utime()
              # depends on the platform: 1 sec, 1 us, 1 ns. Writing a portable
              # test with a resolution of 1 ns requires more work:
              # see the issue #15745.
              atime_ns = 1002003000   # 1.002003 seconds
              mtime_ns = 4005006000   # 4.005006 seconds
          else:
              # use a resolution of 1 second
              atime_ns = 5 * 10**9
              mtime_ns = 8 * 10**9
  
          set_time(filename, (atime_ns, mtime_ns))
          st = os.stat(filename)
  
          if support_subsecond:
              self.assertAlmostEqual(st.st_atime, atime_ns * 1e-9, delta=1e-6)
              self.assertAlmostEqual(st.st_mtime, mtime_ns * 1e-9, delta=1e-6)
          else:
              self.assertEqual(st.st_atime, atime_ns * 1e-9)
              self.assertEqual(st.st_mtime, mtime_ns * 1e-9)
          self.assertEqual(st.st_atime_ns, atime_ns)
          self.assertEqual(st.st_mtime_ns, mtime_ns)
  
      def test_utime(self):
          def set_time(filename, ns):
              # test the ns keyword parameter
              os.utime(filename, ns=ns)
          self._test_utime(set_time)
  
      @staticmethod
      def ns_to_sec(ns):
          # Convert a number of nanosecond (int) to a number of seconds (float).
          # Round towards infinity by adding 0.5 nanosecond to avoid rounding
          # issue, os.utime() rounds towards minus infinity.
          return (ns * 1e-9) + 0.5e-9
  
      def test_utime_by_indexed(self):
          # pass times as floating point seconds as the second indexed parameter
          def set_time(filename, ns):
              atime_ns, mtime_ns = ns
              atime = self.ns_to_sec(atime_ns)
              mtime = self.ns_to_sec(mtime_ns)
              # test utimensat(timespec), utimes(timeval), utime(utimbuf)
              # or utime(time_t)
              os.utime(filename, (atime, mtime))
          self._test_utime(set_time)
  
      def test_utime_by_times(self):
          def set_time(filename, ns):
              atime_ns, mtime_ns = ns
              atime = self.ns_to_sec(atime_ns)
              mtime = self.ns_to_sec(mtime_ns)
              # test the times keyword parameter
              os.utime(filename, times=(atime, mtime))
          self._test_utime(set_time)
  
      @unittest.skipUnless(os.utime in os.supports_follow_symlinks,
                           "follow_symlinks support for utime required "
                           "for this test.")
      def test_utime_nofollow_symlinks(self):
          def set_time(filename, ns):
              # use follow_symlinks=False to test utimensat(timespec)
              # or lutimes(timeval)
              os.utime(filename, ns=ns, follow_symlinks=False)
          self._test_utime(set_time)
  
      @unittest.skipUnless(os.utime in os.supports_fd,
                           "fd support for utime required for this test.")
      def test_utime_fd(self):
          def set_time(filename, ns):
              with open(filename, 'wb', 0) as fp:
                  # use a file descriptor to test futimens(timespec)
                  # or futimes(timeval)
                  os.utime(fp.fileno(), ns=ns)
          self._test_utime(set_time)
  
      @unittest.skipUnless(os.utime in os.supports_dir_fd,
                           "dir_fd support for utime required for this test.")
      def test_utime_dir_fd(self):
          def set_time(filename, ns):
              dirname, name = os.path.split(filename)
              dirfd = os.open(dirname, os.O_RDONLY)
              try:
                  # pass dir_fd to test utimensat(timespec) or futimesat(timeval)
                  os.utime(name, dir_fd=dirfd, ns=ns)
              finally:
                  os.close(dirfd)
          self._test_utime(set_time)
  
      def test_utime_directory(self):
          def set_time(filename, ns):
              # test calling os.utime() on a directory
              os.utime(filename, ns=ns)
          self._test_utime(set_time, filename=self.dirname)
  
      def _test_utime_current(self, set_time):
          # Get the system clock
          current = time.time()
  
          # Call os.utime() to set the timestamp to the current system clock
          set_time(self.fname)
  
          if not self.support_subsecond(self.fname):
              delta = 1.0
          else:
              # On Windows, the usual resolution of time.time() is 15.6 ms.
              # bpo-30649: Tolerate 50 ms for slow Windows buildbots.
              #
              # x86 Gentoo Refleaks 3.x once failed with dt=20.2 ms. So use
              # also 50 ms on other platforms.
              delta = 0.050
          st = os.stat(self.fname)
          msg = ("st_time=%r, current=%r, dt=%r"
                 % (st.st_mtime, current, st.st_mtime - current))
          self.assertAlmostEqual(st.st_mtime, current,
                                 delta=delta, msg=msg)
  
      def test_utime_current(self):
          def set_time(filename):
              # Set to the current time in the new way
              os.utime(self.fname)
          self._test_utime_current(set_time)
  
      def test_utime_current_old(self):
          def set_time(filename):
              # Set to the current time in the old explicit way.
              os.utime(self.fname, None)
          self._test_utime_current(set_time)
  
      def get_file_system(self, path):
          if sys.platform == 'win32':
              root = os.path.splitdrive(os.path.abspath(path))[0] + '\\'
              import ctypes
              kernel32 = ctypes.windll.kernel32
              buf = ctypes.create_unicode_buffer("", 100)
              ok = kernel32.GetVolumeInformationW(root, None, 0,
                                                  None, None, None,
                                                  buf, len(buf))
              if ok:
                  return buf.value
          # return None if the filesystem is unknown
  
      def test_large_time(self):
          # Many filesystems are limited to the year 2038. At least, the test
          # pass with NTFS filesystem.
          if self.get_file_system(self.dirname) != "NTFS":
              self.skipTest("requires NTFS")
  
          large = 5000000000   # some day in 2128
          os.utime(self.fname, (large, large))
          self.assertEqual(os.stat(self.fname).st_mtime, large)
  
      def test_utime_invalid_arguments(self):
          # seconds and nanoseconds parameters are mutually exclusive
          with self.assertRaises(ValueError):
              os.utime(self.fname, (5, 5), ns=(5, 5))
          with self.assertRaises(TypeError):
              os.utime(self.fname, [5, 5])
          with self.assertRaises(TypeError):
              os.utime(self.fname, (5,))
          with self.assertRaises(TypeError):
              os.utime(self.fname, (5, 5, 5))
          with self.assertRaises(TypeError):
              os.utime(self.fname, ns=[5, 5])
          with self.assertRaises(TypeError):
              os.utime(self.fname, ns=(5,))
          with self.assertRaises(TypeError):
              os.utime(self.fname, ns=(5, 5, 5))
  
          if os.utime not in os.supports_follow_symlinks:
              with self.assertRaises(NotImplementedError):
                  os.utime(self.fname, (5, 5), follow_symlinks=False)
          if os.utime not in os.supports_fd:
              with open(self.fname, 'wb', 0) as fp:
                  with self.assertRaises(TypeError):
                      os.utime(fp.fileno(), (5, 5))
          if os.utime not in os.supports_dir_fd:
              with self.assertRaises(NotImplementedError):
                  os.utime(self.fname, (5, 5), dir_fd=0)
  
      @support.cpython_only
      def test_issue31577(self):
          # The interpreter shouldn't crash in case utime() received a bad
          # ns argument.
          def get_bad_int(divmod_ret_val):
              class BadInt:
                  def __divmod__(*args):
                      return divmod_ret_val
              return BadInt()
          with self.assertRaises(TypeError):
              os.utime(self.fname, ns=(get_bad_int(42), 1))
          with self.assertRaises(TypeError):
              os.utime(self.fname, ns=(get_bad_int(()), 1))
          with self.assertRaises(TypeError):
              os.utime(self.fname, ns=(get_bad_int((1, 2, 3)), 1))
  
  
  from test import mapping_tests
  
  class EnvironTests(mapping_tests.BasicTestMappingProtocol):
      """check that os.environ object conform to mapping protocol"""
      type2test = None
  
      def setUp(self):
          self.__save = dict(os.environ)
          if os.supports_bytes_environ:
              self.__saveb = dict(os.environb)
          for key, value in self._reference().items():
              os.environ[key] = value
  
      def tearDown(self):
          os.environ.clear()
          os.environ.update(self.__save)
          if os.supports_bytes_environ:
              os.environb.clear()
              os.environb.update(self.__saveb)
  
      def _reference(self):
          return {"KEY1":"VALUE1", "KEY2":"VALUE2", "KEY3":"VALUE3"}
  
      def _empty_mapping(self):
          os.environ.clear()
          return os.environ
  
      # Bug 1110478
      @unittest.skipUnless(unix_shell and os.path.exists(unix_shell),
                           'requires a shell')
      def test_update2(self):
          os.environ.clear()
          os.environ.update(HELLO="World")
          with os.popen("%s -c 'echo $HELLO'" % unix_shell) as popen:
              value = popen.read().strip()
              self.assertEqual(value, "World")
  
      @unittest.skipUnless(unix_shell and os.path.exists(unix_shell),
                           'requires a shell')
      def test_os_popen_iter(self):
          with os.popen("%s -c 'echo \"line1\nline2\nline3\"'"
                        % unix_shell) as popen:
              it = iter(popen)
              self.assertEqual(next(it), "line1\n")
              self.assertEqual(next(it), "line2\n")
              self.assertEqual(next(it), "line3\n")
              self.assertRaises(StopIteration, next, it)
  
      # Verify environ keys and values from the OS are of the
      # correct str type.
      def test_keyvalue_types(self):
          for key, val in os.environ.items():
              self.assertEqual(type(key), str)
              self.assertEqual(type(val), str)
  
      def test_items(self):
          for key, value in self._reference().items():
              self.assertEqual(os.environ.get(key), value)
  
      # Issue 7310
      def test___repr__(self):
          """Check that the repr() of os.environ looks like environ({...})."""
          env = os.environ
          self.assertEqual(repr(env), 'environ({{{}}})'.format(', '.join(
              '{!r}: {!r}'.format(key, value)
              for key, value in env.items())))
  
      def test_get_exec_path(self):
          defpath_list = os.defpath.split(os.pathsep)
          test_path = ['/monty', '/python', '', '/flying/circus']
          test_env = {'PATH': os.pathsep.join(test_path)}
  
          saved_environ = os.environ
          try:
              os.environ = dict(test_env)
              # Test that defaulting to os.environ works.
              self.assertSequenceEqual(test_path, os.get_exec_path())
              self.assertSequenceEqual(test_path, os.get_exec_path(env=None))
          finally:
              os.environ = saved_environ
  
          # No PATH environment variable
          self.assertSequenceEqual(defpath_list, os.get_exec_path({}))
          # Empty PATH environment variable
          self.assertSequenceEqual(('',), os.get_exec_path({'PATH':''}))
          # Supplied PATH environment variable
          self.assertSequenceEqual(test_path, os.get_exec_path(test_env))
  
          if os.supports_bytes_environ:
              # env cannot contain 'PATH' and b'PATH' keys
              try:
                  # ignore BytesWarning warning
                  with warnings.catch_warnings(record=True):
                      mixed_env = {'PATH': '1', b'PATH': b'2'}
              except BytesWarning:
                  # mixed_env cannot be created with python -bb
                  pass
              else:
                  self.assertRaises(ValueError, os.get_exec_path, mixed_env)
  
              # bytes key and/or value
              self.assertSequenceEqual(os.get_exec_path({b'PATH': b'abc'}),
                  ['abc'])
              self.assertSequenceEqual(os.get_exec_path({b'PATH': 'abc'}),
                  ['abc'])
              self.assertSequenceEqual(os.get_exec_path({'PATH': b'abc'}),
                  ['abc'])
  
      @unittest.skipUnless(os.supports_bytes_environ,
                           "os.environb required for this test.")
      def test_environb(self):
          # os.environ -> os.environb
          value = 'euro\u20ac'
          try:
              value_bytes = value.encode(sys.getfilesystemencoding(),
                                         'surrogateescape')
          except UnicodeEncodeError:
              msg = "U+20AC character is not encodable to %s" % (
                  sys.getfilesystemencoding(),)
              self.skipTest(msg)
          os.environ['unicode'] = value
          self.assertEqual(os.environ['unicode'], value)
          self.assertEqual(os.environb[b'unicode'], value_bytes)
  
          # os.environb -> os.environ
          value = b'\xff'
          os.environb[b'bytes'] = value
          self.assertEqual(os.environb[b'bytes'], value)
          value_str = value.decode(sys.getfilesystemencoding(), 'surrogateescape')
          self.assertEqual(os.environ['bytes'], value_str)
  
      # On OS X < 10.6, unsetenv() doesn't return a value (bpo-13415).
      @support.requires_mac_ver(10, 6)
      def test_unset_error(self):
          if sys.platform == "win32":
              # an environment variable is limited to 32,767 characters
              key = 'x' * 50000
              self.assertRaises(ValueError, os.environ.__delitem__, key)
          else:
              # "=" is not allowed in a variable name
              key = 'key='
              self.assertRaises(OSError, os.environ.__delitem__, key)
  
      def test_key_type(self):
          missing = 'missingkey'
          self.assertNotIn(missing, os.environ)
  
          with self.assertRaises(KeyError) as cm:
              os.environ[missing]
          self.assertIs(cm.exception.args[0], missing)
          self.assertTrue(cm.exception.__suppress_context__)
  
          with self.assertRaises(KeyError) as cm:
              del os.environ[missing]
          self.assertIs(cm.exception.args[0], missing)
          self.assertTrue(cm.exception.__suppress_context__)
  
      def _test_environ_iteration(self, collection):
          iterator = iter(collection)
          new_key = "__new_key__"
  
          next(iterator)  # start iteration over os.environ.items
  
          # add a new key in os.environ mapping
          os.environ[new_key] = "test_environ_iteration"
  
          try:
              next(iterator)  # force iteration over modified mapping
              self.assertEqual(os.environ[new_key], "test_environ_iteration")
          finally:
              del os.environ[new_key]
  
      def test_iter_error_when_changing_os_environ(self):
          self._test_environ_iteration(os.environ)
  
      def test_iter_error_when_changing_os_environ_items(self):
          self._test_environ_iteration(os.environ.items())
  
      def test_iter_error_when_changing_os_environ_values(self):
          self._test_environ_iteration(os.environ.values())
  
  
  class WalkTests(unittest.TestCase):
      """Tests for os.walk()."""
  
      # Wrapper to hide minor differences between os.walk and os.fwalk
      # to tests both functions with the same code base
      def walk(self, top, **kwargs):
          if 'follow_symlinks' in kwargs:
              kwargs['followlinks'] = kwargs.pop('follow_symlinks')
          return os.walk(top, **kwargs)
  
      def setUp(self):
          join = os.path.join
          self.addCleanup(support.rmtree, support.TESTFN)
  
          # Build:
          #     TESTFN/
          #       TEST1/              a file kid and two directory kids
          #         tmp1
          #         SUB1/             a file kid and a directory kid
          #           tmp2
          #           SUB11/          no kids
          #         SUB2/             a file kid and a dirsymlink kid
          #           tmp3
          #           SUB21/          not readable
          #             tmp5
          #           link/           a symlink to TESTFN.2
          #           broken_link
          #           broken_link2
          #           broken_link3
          #       TEST2/
          #         tmp4              a lone file
          self.walk_path = join(support.TESTFN, "TEST1")
          self.sub1_path = join(self.walk_path, "SUB1")
          self.sub11_path = join(self.sub1_path, "SUB11")
          sub2_path = join(self.walk_path, "SUB2")
          sub21_path = join(sub2_path, "SUB21")
          tmp1_path = join(self.walk_path, "tmp1")
          tmp2_path = join(self.sub1_path, "tmp2")
          tmp3_path = join(sub2_path, "tmp3")
          tmp5_path = join(sub21_path, "tmp3")
          self.link_path = join(sub2_path, "link")
          t2_path = join(support.TESTFN, "TEST2")
          tmp4_path = join(support.TESTFN, "TEST2", "tmp4")
          broken_link_path = join(sub2_path, "broken_link")
          broken_link2_path = join(sub2_path, "broken_link2")
          broken_link3_path = join(sub2_path, "broken_link3")
  
          # Create stuff.
          os.makedirs(self.sub11_path)
          os.makedirs(sub2_path)
          os.makedirs(sub21_path)
          os.makedirs(t2_path)
  
          for path in tmp1_path, tmp2_path, tmp3_path, tmp4_path, tmp5_path:
              with open(path, "x") as f:
                  f.write("I'm " + path + " and proud of it.  Blame test_os.\n")
  
          if support.can_symlink():
              os.symlink(os.path.abspath(t2_path), self.link_path)
              os.symlink('broken', broken_link_path, True)
              os.symlink(join('tmp3', 'broken'), broken_link2_path, True)
              os.symlink(join('SUB21', 'tmp5'), broken_link3_path, True)
              self.sub2_tree = (sub2_path, ["SUB21", "link"],
                                ["broken_link", "broken_link2", "broken_link3",
                                 "tmp3"])
          else:
              self.sub2_tree = (sub2_path, ["SUB21"], ["tmp3"])
  
          os.chmod(sub21_path, 0)
          try:
              os.listdir(sub21_path)
          except PermissionError:
              self.addCleanup(os.chmod, sub21_path, stat.S_IRWXU)
          else:
              os.chmod(sub21_path, stat.S_IRWXU)
              os.unlink(tmp5_path)
              os.rmdir(sub21_path)
              del self.sub2_tree[1][:1]
  
      def test_walk_topdown(self):
          # Walk top-down.
          all = list(self.walk(self.walk_path))
  
          self.assertEqual(len(all), 4)
          # We can't know which order SUB1 and SUB2 will appear in.
          # Not flipped:  TESTFN, SUB1, SUB11, SUB2
          #     flipped:  TESTFN, SUB2, SUB1, SUB11
          flipped = all[0][1][0] != "SUB1"
          all[0][1].sort()
          all[3 - 2 * flipped][-1].sort()
          all[3 - 2 * flipped][1].sort()
          self.assertEqual(all[0], (self.walk_path, ["SUB1", "SUB2"], ["tmp1"]))
          self.assertEqual(all[1 + flipped], (self.sub1_path, ["SUB11"], ["tmp2"]))
          self.assertEqual(all[2 + flipped], (self.sub11_path, [], []))
          self.assertEqual(all[3 - 2 * flipped], self.sub2_tree)
  
      def test_walk_prune(self, walk_path=None):
          if walk_path is None:
              walk_path = self.walk_path
          # Prune the search.
          all = []
          for root, dirs, files in self.walk(walk_path):
              all.append((root, dirs, files))
              # Don't descend into SUB1.
              if 'SUB1' in dirs:
                  # Note that this also mutates the dirs we appended to all!
                  dirs.remove('SUB1')
  
          self.assertEqual(len(all), 2)
          self.assertEqual(all[0], (self.walk_path, ["SUB2"], ["tmp1"]))
  
          all[1][-1].sort()
          all[1][1].sort()
          self.assertEqual(all[1], self.sub2_tree)
  
      def test_file_like_path(self):
          self.test_walk_prune(FakePath(self.walk_path))
  
      def test_walk_bottom_up(self):
          # Walk bottom-up.
          all = list(self.walk(self.walk_path, topdown=False))
  
          self.assertEqual(len(all), 4, all)
          # We can't know which order SUB1 and SUB2 will appear in.
          # Not flipped:  SUB11, SUB1, SUB2, TESTFN
          #     flipped:  SUB2, SUB11, SUB1, TESTFN
          flipped = all[3][1][0] != "SUB1"
          all[3][1].sort()
          all[2 - 2 * flipped][-1].sort()
          all[2 - 2 * flipped][1].sort()
          self.assertEqual(all[3],
                           (self.walk_path, ["SUB1", "SUB2"], ["tmp1"]))
          self.assertEqual(all[flipped],
                           (self.sub11_path, [], []))
          self.assertEqual(all[flipped + 1],
                           (self.sub1_path, ["SUB11"], ["tmp2"]))
          self.assertEqual(all[2 - 2 * flipped],
                           self.sub2_tree)
  
      def test_walk_symlink(self):
          if not support.can_symlink():
              self.skipTest("need symlink support")
  
          # Walk, following symlinks.
          walk_it = self.walk(self.walk_path, follow_symlinks=True)
          for root, dirs, files in walk_it:
              if root == self.link_path:
                  self.assertEqual(dirs, [])
                  self.assertEqual(files, ["tmp4"])
                  break
          else:
              self.fail("Didn't follow symlink with followlinks=True")
  
      def test_walk_bad_dir(self):
          # Walk top-down.
          errors = []
          walk_it = self.walk(self.walk_path, onerror=errors.append)
          root, dirs, files = next(walk_it)
          self.assertEqual(errors, [])
          dir1 = 'SUB1'
          path1 = os.path.join(root, dir1)
          path1new = os.path.join(root, dir1 + '.new')
          os.rename(path1, path1new)
          try:
              roots = [r for r, d, f in walk_it]
              self.assertTrue(errors)
              self.assertNotIn(path1, roots)
              self.assertNotIn(path1new, roots)
              for dir2 in dirs:
                  if dir2 != dir1:
                      self.assertIn(os.path.join(root, dir2), roots)
          finally:
              os.rename(path1new, path1)
  
      def test_walk_many_open_files(self):
          depth = 30
          base = os.path.join(support.TESTFN, 'deep')
          p = os.path.join(base, *(['d']*depth))
          os.makedirs(p)
  
          iters = [self.walk(base, topdown=False) for j in range(100)]
          for i in range(depth + 1):
              expected = (p, ['d'] if i else [], [])
              for it in iters:
                  self.assertEqual(next(it), expected)
              p = os.path.dirname(p)
  
          iters = [self.walk(base, topdown=True) for j in range(100)]
          p = base
          for i in range(depth + 1):
              expected = (p, ['d'] if i < depth else [], [])
              for it in iters:
                  self.assertEqual(next(it), expected)
              p = os.path.join(p, 'd')
  
  
  @unittest.skipUnless(hasattr(os, 'fwalk'), "Test needs os.fwalk()")
  class FwalkTests(WalkTests):
      """Tests for os.fwalk()."""
  
      def walk(self, top, **kwargs):
          for root, dirs, files, root_fd in self.fwalk(top, **kwargs):
              yield (root, dirs, files)
  
      def fwalk(self, *args, **kwargs):
          return os.fwalk(*args, **kwargs)
  
      def _compare_to_walk(self, walk_kwargs, fwalk_kwargs):
          """
          compare with walk() results.
          """
          walk_kwargs = walk_kwargs.copy()
          fwalk_kwargs = fwalk_kwargs.copy()
          for topdown, follow_symlinks in itertools.product((True, False), repeat=2):
              walk_kwargs.update(topdown=topdown, followlinks=follow_symlinks)
              fwalk_kwargs.update(topdown=topdown, follow_symlinks=follow_symlinks)
  
              expected = {}
              for root, dirs, files in os.walk(**walk_kwargs):
                  expected[root] = (set(dirs), set(files))
  
              for root, dirs, files, rootfd in self.fwalk(**fwalk_kwargs):
                  self.assertIn(root, expected)
                  self.assertEqual(expected[root], (set(dirs), set(files)))
  
      def test_compare_to_walk(self):
          kwargs = {'top': support.TESTFN}
          self._compare_to_walk(kwargs, kwargs)
  
      def test_dir_fd(self):
          try:
              fd = os.open(".", os.O_RDONLY)
              walk_kwargs = {'top': support.TESTFN}
              fwalk_kwargs = walk_kwargs.copy()
              fwalk_kwargs['dir_fd'] = fd
              self._compare_to_walk(walk_kwargs, fwalk_kwargs)
          finally:
              os.close(fd)
  
      def test_yields_correct_dir_fd(self):
          # check returned file descriptors
          for topdown, follow_symlinks in itertools.product((True, False), repeat=2):
              args = support.TESTFN, topdown, None
              for root, dirs, files, rootfd in self.fwalk(*args, follow_symlinks=follow_symlinks):
                  # check that the FD is valid
                  os.fstat(rootfd)
                  # redundant check
                  os.stat(rootfd)
                  # check that listdir() returns consistent information
                  self.assertEqual(set(os.listdir(rootfd)), set(dirs) | set(files))
  
      def test_fd_leak(self):
          # Since we're opening a lot of FDs, we must be careful to avoid leaks:
          # we both check that calling fwalk() a large number of times doesn't
          # yield EMFILE, and that the minimum allocated FD hasn't changed.
          minfd = os.dup(1)
          os.close(minfd)
          for i in range(256):
              for x in self.fwalk(support.TESTFN):
                  pass
          newfd = os.dup(1)
          self.addCleanup(os.close, newfd)
          self.assertEqual(newfd, minfd)
  
      # fwalk() keeps file descriptors open
      test_walk_many_open_files = None
  
  
  class BytesWalkTests(WalkTests):
      """Tests for os.walk() with bytes."""
      def walk(self, top, **kwargs):
          if 'follow_symlinks' in kwargs:
              kwargs['followlinks'] = kwargs.pop('follow_symlinks')
          for broot, bdirs, bfiles in os.walk(os.fsencode(top), **kwargs):
              root = os.fsdecode(broot)
              dirs = list(map(os.fsdecode, bdirs))
              files = list(map(os.fsdecode, bfiles))
              yield (root, dirs, files)
              bdirs[:] = list(map(os.fsencode, dirs))
              bfiles[:] = list(map(os.fsencode, files))
  
  @unittest.skipUnless(hasattr(os, 'fwalk'), "Test needs os.fwalk()")
  class BytesFwalkTests(FwalkTests):
      """Tests for os.walk() with bytes."""
      def fwalk(self, top='.', *args, **kwargs):
          for broot, bdirs, bfiles, topfd in os.fwalk(os.fsencode(top), *args, **kwargs):
              root = os.fsdecode(broot)
              dirs = list(map(os.fsdecode, bdirs))
              files = list(map(os.fsdecode, bfiles))
              yield (root, dirs, files, topfd)
              bdirs[:] = list(map(os.fsencode, dirs))
              bfiles[:] = list(map(os.fsencode, files))
  
  
  class MakedirTests(unittest.TestCase):
      def setUp(self):
          os.mkdir(support.TESTFN)
  
      def test_makedir(self):
          base = support.TESTFN
          path = os.path.join(base, 'dir1', 'dir2', 'dir3')
          os.makedirs(path)             # Should work
          path = os.path.join(base, 'dir1', 'dir2', 'dir3', 'dir4')
          os.makedirs(path)
  
          # Try paths with a '.' in them
          self.assertRaises(OSError, os.makedirs, os.curdir)
          path = os.path.join(base, 'dir1', 'dir2', 'dir3', 'dir4', 'dir5', os.curdir)
          os.makedirs(path)
          path = os.path.join(base, 'dir1', os.curdir, 'dir2', 'dir3', 'dir4',
                              'dir5', 'dir6')
          os.makedirs(path)
  
      def test_mode(self):
          with support.temp_umask(0o002):
              base = support.TESTFN
              parent = os.path.join(base, 'dir1')
              path = os.path.join(parent, 'dir2')
              os.makedirs(path, 0o555)
              self.assertTrue(os.path.exists(path))
              self.assertTrue(os.path.isdir(path))
              if os.name != 'nt':
                  self.assertEqual(os.stat(path).st_mode & 0o777, 0o555)
                  self.assertEqual(os.stat(parent).st_mode & 0o777, 0o775)
  
      def test_exist_ok_existing_directory(self):
          path = os.path.join(support.TESTFN, 'dir1')
          mode = 0o777
          old_mask = os.umask(0o022)
          os.makedirs(path, mode)
          self.assertRaises(OSError, os.makedirs, path, mode)
          self.assertRaises(OSError, os.makedirs, path, mode, exist_ok=False)
          os.makedirs(path, 0o776, exist_ok=True)
          os.makedirs(path, mode=mode, exist_ok=True)
          os.umask(old_mask)
  
          # Issue #25583: A drive root could raise PermissionError on Windows
          os.makedirs(os.path.abspath('/'), exist_ok=True)
  
      def test_exist_ok_s_isgid_directory(self):
          path = os.path.join(support.TESTFN, 'dir1')
          S_ISGID = stat.S_ISGID
          mode = 0o777
          old_mask = os.umask(0o022)
          try:
              existing_testfn_mode = stat.S_IMODE(
                      os.lstat(support.TESTFN).st_mode)
              try:
                  os.chmod(support.TESTFN, existing_testfn_mode | S_ISGID)
              except PermissionError:
                  raise unittest.SkipTest('Cannot set S_ISGID for dir.')
              if (os.lstat(support.TESTFN).st_mode & S_ISGID != S_ISGID):
                  raise unittest.SkipTest('No support for S_ISGID dir mode.')
              # The os should apply S_ISGID from the parent dir for us, but
              # this test need not depend on that behavior.  Be explicit.
              os.makedirs(path, mode | S_ISGID)
              # http://bugs.python.org/issue14992
              # Should not fail when the bit is already set.
              os.makedirs(path, mode, exist_ok=True)
              # remove the bit.
              os.chmod(path, stat.S_IMODE(os.lstat(path).st_mode) & ~S_ISGID)
              # May work even when the bit is not already set when demanded.
              os.makedirs(path, mode | S_ISGID, exist_ok=True)
          finally:
              os.umask(old_mask)
  
      def test_exist_ok_existing_regular_file(self):
          base = support.TESTFN
          path = os.path.join(support.TESTFN, 'dir1')
          with open(path, 'w') as f:
              f.write('abc')
          self.assertRaises(OSError, os.makedirs, path)
          self.assertRaises(OSError, os.makedirs, path, exist_ok=False)
          self.assertRaises(OSError, os.makedirs, path, exist_ok=True)
          os.remove(path)
  
      def tearDown(self):
          path = os.path.join(support.TESTFN, 'dir1', 'dir2', 'dir3',
                              'dir4', 'dir5', 'dir6')
          # If the tests failed, the bottom-most directory ('../dir6')
          # may not have been created, so we look for the outermost directory
          # that exists.
          while not os.path.exists(path) and path != support.TESTFN:
              path = os.path.dirname(path)
  
          os.removedirs(path)
  
  
  @unittest.skipUnless(hasattr(os, 'chown'), "Test needs chown")
  class ChownFileTests(unittest.TestCase):
  
      @classmethod
      def setUpClass(cls):
          os.mkdir(support.TESTFN)
  
      def test_chown_uid_gid_arguments_must_be_index(self):
          stat = os.stat(support.TESTFN)
          uid = stat.st_uid
          gid = stat.st_gid
          for value in (-1.0, -1j, decimal.Decimal(-1), fractions.Fraction(-2, 2)):
              self.assertRaises(TypeError, os.chown, support.TESTFN, value, gid)
              self.assertRaises(TypeError, os.chown, support.TESTFN, uid, value)
          self.assertIsNone(os.chown(support.TESTFN, uid, gid))
          self.assertIsNone(os.chown(support.TESTFN, -1, -1))
  
      @unittest.skipUnless(hasattr(os, 'getgroups'), 'need os.getgroups')
      def test_chown_gid(self):
          groups = os.getgroups()
          if len(groups) < 2:
              self.skipTest("test needs at least 2 groups")
  
          gid_1, gid_2 = groups[:2]
          uid = os.stat(support.TESTFN).st_uid
  
          os.chown(support.TESTFN, uid, gid_1)
          gid = os.stat(support.TESTFN).st_gid
          self.assertEqual(gid, gid_1)
  
          os.chown(support.TESTFN, uid, gid_2)
          gid = os.stat(support.TESTFN).st_gid
          self.assertEqual(gid, gid_2)
  
      @unittest.skipUnless(root_in_posix and len(all_users) > 1,
                           "test needs root privilege and more than one user")
      def test_chown_with_root(self):
          uid_1, uid_2 = all_users[:2]
          gid = os.stat(support.TESTFN).st_gid
          os.chown(support.TESTFN, uid_1, gid)
          uid = os.stat(support.TESTFN).st_uid
          self.assertEqual(uid, uid_1)
          os.chown(support.TESTFN, uid_2, gid)
          uid = os.stat(support.TESTFN).st_uid
          self.assertEqual(uid, uid_2)
  
      @unittest.skipUnless(not root_in_posix and len(all_users) > 1,
                           "test needs non-root account and more than one user")
      def test_chown_without_permission(self):
          uid_1, uid_2 = all_users[:2]
          gid = os.stat(support.TESTFN).st_gid
          with self.assertRaises(PermissionError):
              os.chown(support.TESTFN, uid_1, gid)
              os.chown(support.TESTFN, uid_2, gid)
  
      @classmethod
      def tearDownClass(cls):
          os.rmdir(support.TESTFN)
  
  
  class RemoveDirsTests(unittest.TestCase):
      def setUp(self):
          os.makedirs(support.TESTFN)
  
      def tearDown(self):
          support.rmtree(support.TESTFN)
  
      def test_remove_all(self):
          dira = os.path.join(support.TESTFN, 'dira')
          os.mkdir(dira)
          dirb = os.path.join(dira, 'dirb')
          os.mkdir(dirb)
          os.removedirs(dirb)
          self.assertFalse(os.path.exists(dirb))
          self.assertFalse(os.path.exists(dira))
          self.assertFalse(os.path.exists(support.TESTFN))
  
      def test_remove_partial(self):
          dira = os.path.join(support.TESTFN, 'dira')
          os.mkdir(dira)
          dirb = os.path.join(dira, 'dirb')
          os.mkdir(dirb)
          create_file(os.path.join(dira, 'file.txt'))
          os.removedirs(dirb)
          self.assertFalse(os.path.exists(dirb))
          self.assertTrue(os.path.exists(dira))
          self.assertTrue(os.path.exists(support.TESTFN))
  
      def test_remove_nothing(self):
          dira = os.path.join(support.TESTFN, 'dira')
          os.mkdir(dira)
          dirb = os.path.join(dira, 'dirb')
          os.mkdir(dirb)
          create_file(os.path.join(dirb, 'file.txt'))
          with self.assertRaises(OSError):
              os.removedirs(dirb)
          self.assertTrue(os.path.exists(dirb))
          self.assertTrue(os.path.exists(dira))
          self.assertTrue(os.path.exists(support.TESTFN))
  
  
  class DevNullTests(unittest.TestCase):
      def test_devnull(self):
          with open(os.devnull, 'wb', 0) as f:
              f.write(b'hello')
              f.close()
          with open(os.devnull, 'rb') as f:
              self.assertEqual(f.read(), b'')
  
  
  class URandomTests(unittest.TestCase):
      def test_urandom_length(self):
          self.assertEqual(len(os.urandom(0)), 0)
          self.assertEqual(len(os.urandom(1)), 1)
          self.assertEqual(len(os.urandom(10)), 10)
          self.assertEqual(len(os.urandom(100)), 100)
          self.assertEqual(len(os.urandom(1000)), 1000)
  
      def test_urandom_value(self):
          data1 = os.urandom(16)
          self.assertIsInstance(data1, bytes)
          data2 = os.urandom(16)
          self.assertNotEqual(data1, data2)
  
      def get_urandom_subprocess(self, count):
          code = '\n'.join((
              'import os, sys',
              'data = os.urandom(%s)' % count,
              'sys.stdout.buffer.write(data)',
              'sys.stdout.buffer.flush()'))
          out = assert_python_ok('-c', code)
          stdout = out[1]
          self.assertEqual(len(stdout), count)
          return stdout
  
      def test_urandom_subprocess(self):
          data1 = self.get_urandom_subprocess(16)
          data2 = self.get_urandom_subprocess(16)
          self.assertNotEqual(data1, data2)
  
  
  @unittest.skipUnless(hasattr(os, 'getrandom'), 'need os.getrandom()')
  class GetRandomTests(unittest.TestCase):
      @classmethod
      def setUpClass(cls):
          try:
              os.getrandom(1)
          except OSError as exc:
              if exc.errno == errno.ENOSYS:
                  # Python compiled on a more recent Linux version
                  # than the current Linux kernel
                  raise unittest.SkipTest("getrandom() syscall fails with ENOSYS")
              else:
                  raise
  
      def test_getrandom_type(self):
          data = os.getrandom(16)
          self.assertIsInstance(data, bytes)
          self.assertEqual(len(data), 16)
  
      def test_getrandom0(self):
          empty = os.getrandom(0)
          self.assertEqual(empty, b'')
  
      def test_getrandom_random(self):
          self.assertTrue(hasattr(os, 'GRND_RANDOM'))
  
          # Don't test os.getrandom(1, os.GRND_RANDOM) to not consume the rare
          # resource /dev/random
  
      def test_getrandom_nonblock(self):
          # The call must not fail. Check also that the flag exists
          try:
              os.getrandom(1, os.GRND_NONBLOCK)
          except BlockingIOError:
              # System urandom is not initialized yet
              pass
  
      def test_getrandom_value(self):
          data1 = os.getrandom(16)
          data2 = os.getrandom(16)
          self.assertNotEqual(data1, data2)
  
  
  # os.urandom() doesn't use a file descriptor when it is implemented with the
  # getentropy() function, the getrandom() function or the getrandom() syscall
  OS_URANDOM_DONT_USE_FD = (
      sysconfig.get_config_var('HAVE_GETENTROPY') == 1
      or sysconfig.get_config_var('HAVE_GETRANDOM') == 1
      or sysconfig.get_config_var('HAVE_GETRANDOM_SYSCALL') == 1)
  
  @unittest.skipIf(OS_URANDOM_DONT_USE_FD ,
                   "os.random() does not use a file descriptor")
  @unittest.skipIf(sys.platform == "vxworks",
                   "VxWorks can't set RLIMIT_NOFILE to 1")
  class URandomFDTests(unittest.TestCase):
      @unittest.skipUnless(resource, "test requires the resource module")
      def test_urandom_failure(self):
          # Check urandom() failing when it is not able to open /dev/random.
          # We spawn a new process to make the test more robust (if getrlimit()
          # failed to restore the file descriptor limit after this, the whole
          # test suite would crash; this actually happened on the OS X Tiger
          # buildbot).
          code = """if 1:
              import errno
              import os
              import resource
  
              soft_limit, hard_limit = resource.getrlimit(resource.RLIMIT_NOFILE)
              resource.setrlimit(resource.RLIMIT_NOFILE, (1, hard_limit))
              try:
                  os.urandom(16)
              except OSError as e:
                  assert e.errno == errno.EMFILE, e.errno
              else:
                  raise AssertionError("OSError not raised")
              """
          assert_python_ok('-c', code)
  
      def test_urandom_fd_closed(self):
          # Issue #21207: urandom() should reopen its fd to /dev/urandom if
          # closed.
          code = """if 1:
              import os
              import sys
              import test.support
              os.urandom(4)
              with test.support.SuppressCrashReport():
                  os.closerange(3, 256)
              sys.stdout.buffer.write(os.urandom(4))
              """
          rc, out, err = assert_python_ok('-Sc', code)
  
      def test_urandom_fd_reopened(self):
          # Issue #21207: urandom() should detect its fd to /dev/urandom
          # changed to something else, and reopen it.
          self.addCleanup(support.unlink, support.TESTFN)
          create_file(support.TESTFN, b"x" * 256)
  
          code = """if 1:
              import os
              import sys
              import test.support
              os.urandom(4)
              with test.support.SuppressCrashReport():
                  for fd in range(3, 256):
                      try:
                          os.close(fd)
                      except OSError:
                          pass
                      else:
                          # Found the urandom fd (XXX hopefully)
                          break
                  os.closerange(3, 256)
              with open({TESTFN!r}, 'rb') as f:
                  new_fd = f.fileno()
                  # Issue #26935: posix allows new_fd and fd to be equal but
                  # some libc implementations have dup2 return an error in this
                  # case.
                  if new_fd != fd:
                      os.dup2(new_fd, fd)
                  sys.stdout.buffer.write(os.urandom(4))
                  sys.stdout.buffer.write(os.urandom(4))
              """.format(TESTFN=support.TESTFN)
          rc, out, err = assert_python_ok('-Sc', code)
          self.assertEqual(len(out), 8)
          self.assertNotEqual(out[0:4], out[4:8])
          rc, out2, err2 = assert_python_ok('-Sc', code)
          self.assertEqual(len(out2), 8)
          self.assertNotEqual(out2, out)
  
  
  @contextlib.contextmanager
  def _execvpe_mockup(defpath=None):
      """
      Stubs out execv and execve functions when used as context manager.
      Records exec calls. The mock execv and execve functions always raise an
      exception as they would normally never return.
      """
      # A list of tuples containing (function name, first arg, args)
      # of calls to execv or execve that have been made.
      calls = []
  
      def mock_execv(name, *args):
          calls.append(('execv', name, args))
          raise RuntimeError("execv called")
  
      def mock_execve(name, *args):
          calls.append(('execve', name, args))
          raise OSError(errno.ENOTDIR, "execve called")
  
      try:
          orig_execv = os.execv
          orig_execve = os.execve
          orig_defpath = os.defpath
          os.execv = mock_execv
          os.execve = mock_execve
          if defpath is not None:
              os.defpath = defpath
          yield calls
      finally:
          os.execv = orig_execv
          os.execve = orig_execve
          os.defpath = orig_defpath
  
  @unittest.skipUnless(hasattr(os, 'execv'),
                       "need os.execv()")
  class ExecTests(unittest.TestCase):
      @unittest.skipIf(USING_LINUXTHREADS,
                       "avoid triggering a linuxthreads bug: see issue #4970")
      def test_execvpe_with_bad_program(self):
          self.assertRaises(OSError, os.execvpe, 'no such app-',
                            ['no such app-'], None)
  
      def test_execv_with_bad_arglist(self):
          self.assertRaises(ValueError, os.execv, 'notepad', ())
          self.assertRaises(ValueError, os.execv, 'notepad', [])
          self.assertRaises(ValueError, os.execv, 'notepad', ('',))
          self.assertRaises(ValueError, os.execv, 'notepad', [''])
  
      def test_execvpe_with_bad_arglist(self):
          self.assertRaises(ValueError, os.execvpe, 'notepad', [], None)
          self.assertRaises(ValueError, os.execvpe, 'notepad', [], {})
          self.assertRaises(ValueError, os.execvpe, 'notepad', [''], {})
  
      @unittest.skipUnless(hasattr(os, '_execvpe'),
                           "No internal os._execvpe function to test.")
      def _test_internal_execvpe(self, test_type):
          program_path = os.sep + 'absolutepath'
          if test_type is bytes:
              program = b'executable'
              fullpath = os.path.join(os.fsencode(program_path), program)
              native_fullpath = fullpath
              arguments = [b'progname', 'arg1', 'arg2']
          else:
              program = 'executable'
              arguments = ['progname', 'arg1', 'arg2']
              fullpath = os.path.join(program_path, program)
              if os.name != "nt":
                  native_fullpath = os.fsencode(fullpath)
              else:
                  native_fullpath = fullpath
          env = {'spam': 'beans'}
  
          # test os._execvpe() with an absolute path
          with _execvpe_mockup() as calls:
              self.assertRaises(RuntimeError,
                  os._execvpe, fullpath, arguments)
              self.assertEqual(len(calls), 1)
              self.assertEqual(calls[0], ('execv', fullpath, (arguments,)))
  
          # test os._execvpe() with a relative path:
          # os.get_exec_path() returns defpath
          with _execvpe_mockup(defpath=program_path) as calls:
              self.assertRaises(OSError,
                  os._execvpe, program, arguments, env=env)
              self.assertEqual(len(calls), 1)
              self.assertSequenceEqual(calls[0],
                  ('execve', native_fullpath, (arguments, env)))
  
          # test os._execvpe() with a relative path:
          # os.get_exec_path() reads the 'PATH' variable
          with _execvpe_mockup() as calls:
              env_path = env.copy()
              if test_type is bytes:
                  env_path[b'PATH'] = program_path
              else:
                  env_path['PATH'] = program_path
              self.assertRaises(OSError,
                  os._execvpe, program, arguments, env=env_path)
              self.assertEqual(len(calls), 1)
              self.assertSequenceEqual(calls[0],
                  ('execve', native_fullpath, (arguments, env_path)))
  
      def test_internal_execvpe_str(self):
          self._test_internal_execvpe(str)
          if os.name != "nt":
              self._test_internal_execvpe(bytes)
  
      def test_execve_invalid_env(self):
          args = [sys.executable, '-c', 'pass']
  
          # null character in the environment variable name
          newenv = os.environ.copy()
          newenv["FRUIT\0VEGETABLE"] = "cabbage"
          with self.assertRaises(ValueError):
              os.execve(args[0], args, newenv)
  
          # null character in the environment variable value
          newenv = os.environ.copy()
          newenv["FRUIT"] = "orange\0VEGETABLE=cabbage"
          with self.assertRaises(ValueError):
              os.execve(args[0], args, newenv)
  
          # equal character in the environment variable name
          newenv = os.environ.copy()
          newenv["FRUIT=ORANGE"] = "lemon"
          with self.assertRaises(ValueError):
              os.execve(args[0], args, newenv)
  
      @unittest.skipUnless(sys.platform == "win32", "Win32-specific test")
      def test_execve_with_empty_path(self):
          # bpo-32890: Check GetLastError() misuse
          try:
              os.execve('', ['arg'], {})
          except OSError as e:
              self.assertTrue(e.winerror is None or e.winerror != 0)
          else:
              self.fail('No OSError raised')
  
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32ErrorTests(unittest.TestCase):
      def setUp(self):
          try:
              os.stat(support.TESTFN)
          except FileNotFoundError:
              exists = False
          except OSError as exc:
              exists = True
              self.fail("file %s must not exist; os.stat failed with %s"
                        % (support.TESTFN, exc))
          else:
              self.fail("file %s must not exist" % support.TESTFN)
  
      def test_rename(self):
          self.assertRaises(OSError, os.rename, support.TESTFN, support.TESTFN+".bak")
  
      def test_remove(self):
          self.assertRaises(OSError, os.remove, support.TESTFN)
  
      def test_chdir(self):
          self.assertRaises(OSError, os.chdir, support.TESTFN)
  
      def test_mkdir(self):
          self.addCleanup(support.unlink, support.TESTFN)
  
          with open(support.TESTFN, "x") as f:
              self.assertRaises(OSError, os.mkdir, support.TESTFN)
  
      def test_utime(self):
          self.assertRaises(OSError, os.utime, support.TESTFN, None)
  
      def test_chmod(self):
          self.assertRaises(OSError, os.chmod, support.TESTFN, 0)
  
  
  class TestInvalidFD(unittest.TestCase):
      singles = ["fchdir", "dup", "fdopen", "fdatasync", "fstat",
                 "fstatvfs", "fsync", "tcgetpgrp", "ttyname"]
      #singles.append("close")
      #We omit close because it doesn't raise an exception on some platforms
      def get_single(f):
          def helper(self):
              if  hasattr(os, f):
                  self.check(getattr(os, f))
          return helper
      for f in singles:
          locals()["test_"+f] = get_single(f)
  
      def check(self, f, *args):
          try:
              f(support.make_bad_fd(), *args)
          except OSError as e:
              self.assertEqual(e.errno, errno.EBADF)
          else:
              self.fail("%r didn't raise an OSError with a bad file descriptor"
                        % f)
  
      @unittest.skipUnless(hasattr(os, 'isatty'), 'test needs os.isatty()')
      def test_isatty(self):
          self.assertEqual(os.isatty(support.make_bad_fd()), False)
  
      @unittest.skipUnless(hasattr(os, 'closerange'), 'test needs os.closerange()')
      def test_closerange(self):
          fd = support.make_bad_fd()
          # Make sure none of the descriptors we are about to close are
          # currently valid (issue 6542).
          for i in range(10):
              try: os.fstat(fd+i)
              except OSError:
                  pass
              else:
                  break
          if i < 2:
              raise unittest.SkipTest(
                  "Unable to acquire a range of invalid file descriptors")
          self.assertEqual(os.closerange(fd, fd + i-1), None)
  
      @unittest.skipUnless(hasattr(os, 'dup2'), 'test needs os.dup2()')
      def test_dup2(self):
          self.check(os.dup2, 20)
  
      @unittest.skipUnless(hasattr(os, 'fchmod'), 'test needs os.fchmod()')
      def test_fchmod(self):
          self.check(os.fchmod, 0)
  
      @unittest.skipUnless(hasattr(os, 'fchown'), 'test needs os.fchown()')
      def test_fchown(self):
          self.check(os.fchown, -1, -1)
  
      @unittest.skipUnless(hasattr(os, 'fpathconf'), 'test needs os.fpathconf()')
      def test_fpathconf(self):
          self.check(os.pathconf, "PC_NAME_MAX")
          self.check(os.fpathconf, "PC_NAME_MAX")
  
      @unittest.skipUnless(hasattr(os, 'ftruncate'), 'test needs os.ftruncate()')
      def test_ftruncate(self):
          self.check(os.truncate, 0)
          self.check(os.ftruncate, 0)
  
      @unittest.skipUnless(hasattr(os, 'lseek'), 'test needs os.lseek()')
      def test_lseek(self):
          self.check(os.lseek, 0, 0)
  
      @unittest.skipUnless(hasattr(os, 'read'), 'test needs os.read()')
      def test_read(self):
          self.check(os.read, 1)
  
      @unittest.skipUnless(hasattr(os, 'readv'), 'test needs os.readv()')
      def test_readv(self):
          buf = bytearray(10)
          self.check(os.readv, [buf])
  
      @unittest.skipUnless(hasattr(os, 'tcsetpgrp'), 'test needs os.tcsetpgrp()')
      def test_tcsetpgrpt(self):
          self.check(os.tcsetpgrp, 0)
  
      @unittest.skipUnless(hasattr(os, 'write'), 'test needs os.write()')
      def test_write(self):
          self.check(os.write, b" ")
  
      @unittest.skipUnless(hasattr(os, 'writev'), 'test needs os.writev()')
      def test_writev(self):
          self.check(os.writev, [b'abc'])
  
      def test_inheritable(self):
          self.check(os.get_inheritable)
          self.check(os.set_inheritable, True)
  
      @unittest.skipUnless(hasattr(os, 'get_blocking'),
                           'needs os.get_blocking() and os.set_blocking()')
      def test_blocking(self):
          self.check(os.get_blocking)
          self.check(os.set_blocking, True)
  
  
  class LinkTests(unittest.TestCase):
      def setUp(self):
          self.file1 = support.TESTFN
          self.file2 = os.path.join(support.TESTFN + "2")
  
      def tearDown(self):
          for file in (self.file1, self.file2):
              if os.path.exists(file):
                  os.unlink(file)
  
      def _test_link(self, file1, file2):
          create_file(file1)
  
          try:
              os.link(file1, file2)
          except PermissionError as e:
              self.skipTest('os.link(): %s' % e)
          with open(file1, "r") as f1, open(file2, "r") as f2:
              self.assertTrue(os.path.sameopenfile(f1.fileno(), f2.fileno()))
  
      def test_link(self):
          self._test_link(self.file1, self.file2)
  
      def test_link_bytes(self):
          self._test_link(bytes(self.file1, sys.getfilesystemencoding()),
                          bytes(self.file2, sys.getfilesystemencoding()))
  
      def test_unicode_name(self):
          try:
              os.fsencode("\xf1")
          except UnicodeError:
              raise unittest.SkipTest("Unable to encode for this platform.")
  
          self.file1 += "\xf1"
          self.file2 = self.file1 + "2"
          self._test_link(self.file1, self.file2)
  
  @unittest.skipIf(sys.platform == "win32", "Posix specific tests")
  class PosixUidGidTests(unittest.TestCase):
      # uid_t and gid_t are 32-bit unsigned integers on Linux
      UID_OVERFLOW = (1 << 32)
      GID_OVERFLOW = (1 << 32)
  
      @unittest.skipUnless(hasattr(os, 'setuid'), 'test needs os.setuid()')
      def test_setuid(self):
          if os.getuid() != 0:
              self.assertRaises(OSError, os.setuid, 0)
          self.assertRaises(TypeError, os.setuid, 'not an int')
          self.assertRaises(OverflowError, os.setuid, self.UID_OVERFLOW)
  
      @unittest.skipUnless(hasattr(os, 'setgid'), 'test needs os.setgid()')
      def test_setgid(self):
          if os.getuid() != 0 and not HAVE_WHEEL_GROUP:
              self.assertRaises(OSError, os.setgid, 0)
          self.assertRaises(TypeError, os.setgid, 'not an int')
          self.assertRaises(OverflowError, os.setgid, self.GID_OVERFLOW)
  
      @unittest.skipUnless(hasattr(os, 'seteuid'), 'test needs os.seteuid()')
      def test_seteuid(self):
          if os.getuid() != 0:
              self.assertRaises(OSError, os.seteuid, 0)
          self.assertRaises(TypeError, os.setegid, 'not an int')
          self.assertRaises(OverflowError, os.seteuid, self.UID_OVERFLOW)
  
      @unittest.skipUnless(hasattr(os, 'setegid'), 'test needs os.setegid()')
      def test_setegid(self):
          if os.getuid() != 0 and not HAVE_WHEEL_GROUP:
              self.assertRaises(OSError, os.setegid, 0)
          self.assertRaises(TypeError, os.setegid, 'not an int')
          self.assertRaises(OverflowError, os.setegid, self.GID_OVERFLOW)
  
      @unittest.skipUnless(hasattr(os, 'setreuid'), 'test needs os.setreuid()')
      def test_setreuid(self):
          if os.getuid() != 0:
              self.assertRaises(OSError, os.setreuid, 0, 0)
          self.assertRaises(TypeError, os.setreuid, 'not an int', 0)
          self.assertRaises(TypeError, os.setreuid, 0, 'not an int')
          self.assertRaises(OverflowError, os.setreuid, self.UID_OVERFLOW, 0)
          self.assertRaises(OverflowError, os.setreuid, 0, self.UID_OVERFLOW)
  
      @unittest.skipUnless(hasattr(os, 'setreuid'), 'test needs os.setreuid()')
      def test_setreuid_neg1(self):
          # Needs to accept -1.  We run this in a subprocess to avoid
          # altering the test runner's process state (issue8045).
          subprocess.check_call([
                  sys.executable, '-c',
                  'import os,sys;os.setreuid(-1,-1);sys.exit(0)'])
  
      @unittest.skipUnless(hasattr(os, 'setregid'), 'test needs os.setregid()')
      def test_setregid(self):
          if os.getuid() != 0 and not HAVE_WHEEL_GROUP:
              self.assertRaises(OSError, os.setregid, 0, 0)
          self.assertRaises(TypeError, os.setregid, 'not an int', 0)
          self.assertRaises(TypeError, os.setregid, 0, 'not an int')
          self.assertRaises(OverflowError, os.setregid, self.GID_OVERFLOW, 0)
          self.assertRaises(OverflowError, os.setregid, 0, self.GID_OVERFLOW)
  
      @unittest.skipUnless(hasattr(os, 'setregid'), 'test needs os.setregid()')
      def test_setregid_neg1(self):
          # Needs to accept -1.  We run this in a subprocess to avoid
          # altering the test runner's process state (issue8045).
          subprocess.check_call([
                  sys.executable, '-c',
                  'import os,sys;os.setregid(-1,-1);sys.exit(0)'])
  
  @unittest.skipIf(sys.platform == "win32", "Posix specific tests")
  class Pep383Tests(unittest.TestCase):
      def setUp(self):
          if support.TESTFN_UNENCODABLE:
              self.dir = support.TESTFN_UNENCODABLE
          elif support.TESTFN_NONASCII:
              self.dir = support.TESTFN_NONASCII
          else:
              self.dir = support.TESTFN
          self.bdir = os.fsencode(self.dir)
  
          bytesfn = []
          def add_filename(fn):
              try:
                  fn = os.fsencode(fn)
              except UnicodeEncodeError:
                  return
              bytesfn.append(fn)
          add_filename(support.TESTFN_UNICODE)
          if support.TESTFN_UNENCODABLE:
              add_filename(support.TESTFN_UNENCODABLE)
          if support.TESTFN_NONASCII:
              add_filename(support.TESTFN_NONASCII)
          if not bytesfn:
              self.skipTest("couldn't create any non-ascii filename")
  
          self.unicodefn = set()
          os.mkdir(self.dir)
          try:
              for fn in bytesfn:
                  support.create_empty_file(os.path.join(self.bdir, fn))
                  fn = os.fsdecode(fn)
                  if fn in self.unicodefn:
                      raise ValueError("duplicate filename")
                  self.unicodefn.add(fn)
          except:
              shutil.rmtree(self.dir)
              raise
  
      def tearDown(self):
          shutil.rmtree(self.dir)
  
      def test_listdir(self):
          expected = self.unicodefn
          found = set(os.listdir(self.dir))
          self.assertEqual(found, expected)
          # test listdir without arguments
          current_directory = os.getcwd()
          try:
              os.chdir(os.sep)
              self.assertEqual(set(os.listdir()), set(os.listdir(os.sep)))
          finally:
              os.chdir(current_directory)
  
      def test_open(self):
          for fn in self.unicodefn:
              f = open(os.path.join(self.dir, fn), 'rb')
              f.close()
  
      @unittest.skipUnless(hasattr(os, 'statvfs'),
                              "need os.statvfs()")
      def test_statvfs(self):
          # issue #9645
          for fn in self.unicodefn:
              # should not fail with file not found error
              fullname = os.path.join(self.dir, fn)
              os.statvfs(fullname)
  
      def test_stat(self):
          for fn in self.unicodefn:
              os.stat(os.path.join(self.dir, fn))
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32KillTests(unittest.TestCase):
      def _kill(self, sig):
          # Start sys.executable as a subprocess and communicate from the
          # subprocess to the parent that the interpreter is ready. When it
          # becomes ready, send *sig* via os.kill to the subprocess and check
          # that the return code is equal to *sig*.
          import ctypes
          from ctypes import wintypes
          import msvcrt
  
          # Since we can't access the contents of the process' stdout until the
          # process has exited, use PeekNamedPipe to see what's inside stdout
          # without waiting. This is done so we can tell that the interpreter
          # is started and running at a point where it could handle a signal.
          PeekNamedPipe = ctypes.windll.kernel32.PeekNamedPipe
          PeekNamedPipe.restype = wintypes.BOOL
          PeekNamedPipe.argtypes = (wintypes.HANDLE, # Pipe handle
                                    ctypes.POINTER(ctypes.c_char), # stdout buf
                                    wintypes.DWORD, # Buffer size
                                    ctypes.POINTER(wintypes.DWORD), # bytes read
                                    ctypes.POINTER(wintypes.DWORD), # bytes avail
                                    ctypes.POINTER(wintypes.DWORD)) # bytes left
          msg = "running"
          proc = subprocess.Popen([sys.executable, "-c",
                                   "import sys;"
                                   "sys.stdout.write('{}');"
                                   "sys.stdout.flush();"
                                   "input()".format(msg)],
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE,
                                  stdin=subprocess.PIPE)
          self.addCleanup(proc.stdout.close)
          self.addCleanup(proc.stderr.close)
          self.addCleanup(proc.stdin.close)
  
          count, max = 0, 100
          while count < max and proc.poll() is None:
              # Create a string buffer to store the result of stdout from the pipe
              buf = ctypes.create_string_buffer(len(msg))
              # Obtain the text currently in proc.stdout
              # Bytes read/avail/left are left as NULL and unused
              rslt = PeekNamedPipe(msvcrt.get_osfhandle(proc.stdout.fileno()),
                                   buf, ctypes.sizeof(buf), None, None, None)
              self.assertNotEqual(rslt, 0, "PeekNamedPipe failed")
              if buf.value:
                  self.assertEqual(msg, buf.value.decode())
                  break
              time.sleep(0.1)
              count += 1
          else:
              self.fail("Did not receive communication from the subprocess")
  
          os.kill(proc.pid, sig)
          self.assertEqual(proc.wait(), sig)
  
      def test_kill_sigterm(self):
          # SIGTERM doesn't mean anything special, but make sure it works
          self._kill(signal.SIGTERM)
  
      def test_kill_int(self):
          # os.kill on Windows can take an int which gets set as the exit code
          self._kill(100)
  
      def _kill_with_event(self, event, name):
          tagname = "test_os_%s" % uuid.uuid1()
          m = mmap.mmap(-1, 1, tagname)
          m[0] = 0
          # Run a script which has console control handling enabled.
          proc = subprocess.Popen([sys.executable,
                     os.path.join(os.path.dirname(__file__),
                                  "win_console_handler.py"), tagname],
                     creationflags=subprocess.CREATE_NEW_PROCESS_GROUP)
          # Let the interpreter startup before we send signals. See #3137.
          count, max = 0, 100
          while count < max and proc.poll() is None:
              if m[0] == 1:
                  break
              time.sleep(0.1)
              count += 1
          else:
              # Forcefully kill the process if we weren't able to signal it.
              os.kill(proc.pid, signal.SIGINT)
              self.fail("Subprocess didn't finish initialization")
          os.kill(proc.pid, event)
          # proc.send_signal(event) could also be done here.
          # Allow time for the signal to be passed and the process to exit.
          time.sleep(0.5)
          if not proc.poll():
              # Forcefully kill the process if we weren't able to signal it.
              os.kill(proc.pid, signal.SIGINT)
              self.fail("subprocess did not stop on {}".format(name))
  
      @unittest.skip("subprocesses aren't inheriting Ctrl+C property")
      def test_CTRL_C_EVENT(self):
          from ctypes import wintypes
          import ctypes
  
          # Make a NULL value by creating a pointer with no argument.
          NULL = ctypes.POINTER(ctypes.c_int)()
          SetConsoleCtrlHandler = ctypes.windll.kernel32.SetConsoleCtrlHandler
          SetConsoleCtrlHandler.argtypes = (ctypes.POINTER(ctypes.c_int),
                                            wintypes.BOOL)
          SetConsoleCtrlHandler.restype = wintypes.BOOL
  
          # Calling this with NULL and FALSE causes the calling process to
          # handle Ctrl+C, rather than ignore it. This property is inherited
          # by subprocesses.
          SetConsoleCtrlHandler(NULL, 0)
  
          self._kill_with_event(signal.CTRL_C_EVENT, "CTRL_C_EVENT")
  
      def test_CTRL_BREAK_EVENT(self):
          self._kill_with_event(signal.CTRL_BREAK_EVENT, "CTRL_BREAK_EVENT")
  
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32ListdirTests(unittest.TestCase):
      """Test listdir on Windows."""
  
      def setUp(self):
          self.created_paths = []
          for i in range(2):
              dir_name = 'SUB%d' % i
              dir_path = os.path.join(support.TESTFN, dir_name)
              file_name = 'FILE%d' % i
              file_path = os.path.join(support.TESTFN, file_name)
              os.makedirs(dir_path)
              with open(file_path, 'w') as f:
                  f.write("I'm %s and proud of it. Blame test_os.\n" % file_path)
              self.created_paths.extend([dir_name, file_name])
          self.created_paths.sort()
  
      def tearDown(self):
          shutil.rmtree(support.TESTFN)
  
      def test_listdir_no_extended_path(self):
          """Test when the path is not an "extended" path."""
          # unicode
          self.assertEqual(
                  sorted(os.listdir(support.TESTFN)),
                  self.created_paths)
  
          # bytes
          self.assertEqual(
                  sorted(os.listdir(os.fsencode(support.TESTFN))),
                  [os.fsencode(path) for path in self.created_paths])
  
      def test_listdir_extended_path(self):
          """Test when the path starts with '\\\\?\\'."""
          # See: http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath
          # unicode
          path = '\\\\?\\' + os.path.abspath(support.TESTFN)
          self.assertEqual(
                  sorted(os.listdir(path)),
                  self.created_paths)
  
          # bytes
          path = b'\\\\?\\' + os.fsencode(os.path.abspath(support.TESTFN))
          self.assertEqual(
                  sorted(os.listdir(path)),
                  [os.fsencode(path) for path in self.created_paths])
  
  
  @unittest.skipUnless(hasattr(os, 'readlink'), 'needs os.readlink()')
  class ReadlinkTests(unittest.TestCase):
      filelink = 'readlinktest'
      filelink_target = os.path.abspath(__file__)
      filelinkb = os.fsencode(filelink)
      filelinkb_target = os.fsencode(filelink_target)
  
      def assertPathEqual(self, left, right):
          left = os.path.normcase(left)
          right = os.path.normcase(right)
          if sys.platform == 'win32':
              # Bad practice to blindly strip the prefix as it may be required to
              # correctly refer to the file, but we're only comparing paths here.
              has_prefix = lambda p: p.startswith(
                  b'\\\\?\\' if isinstance(p, bytes) else '\\\\?\\')
              if has_prefix(left):
                  left = left[4:]
              if has_prefix(right):
                  right = right[4:]
          self.assertEqual(left, right)
  
      def setUp(self):
          self.assertTrue(os.path.exists(self.filelink_target))
          self.assertTrue(os.path.exists(self.filelinkb_target))
          self.assertFalse(os.path.exists(self.filelink))
          self.assertFalse(os.path.exists(self.filelinkb))
  
      def test_not_symlink(self):
          filelink_target = FakePath(self.filelink_target)
          self.assertRaises(OSError, os.readlink, self.filelink_target)
          self.assertRaises(OSError, os.readlink, filelink_target)
  
      def test_missing_link(self):
          self.assertRaises(FileNotFoundError, os.readlink, 'missing-link')
          self.assertRaises(FileNotFoundError, os.readlink,
                            FakePath('missing-link'))
  
      @support.skip_unless_symlink
      def test_pathlike(self):
          os.symlink(self.filelink_target, self.filelink)
          self.addCleanup(support.unlink, self.filelink)
          filelink = FakePath(self.filelink)
          self.assertPathEqual(os.readlink(filelink), self.filelink_target)
  
      @support.skip_unless_symlink
      def test_pathlike_bytes(self):
          os.symlink(self.filelinkb_target, self.filelinkb)
          self.addCleanup(support.unlink, self.filelinkb)
          path = os.readlink(FakePath(self.filelinkb))
          self.assertPathEqual(path, self.filelinkb_target)
          self.assertIsInstance(path, bytes)
  
      @support.skip_unless_symlink
      def test_bytes(self):
          os.symlink(self.filelinkb_target, self.filelinkb)
          self.addCleanup(support.unlink, self.filelinkb)
          path = os.readlink(self.filelinkb)
          self.assertPathEqual(path, self.filelinkb_target)
          self.assertIsInstance(path, bytes)
  
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  @support.skip_unless_symlink
  class Win32SymlinkTests(unittest.TestCase):
      filelink = 'filelinktest'
      filelink_target = os.path.abspath(__file__)
      dirlink = 'dirlinktest'
      dirlink_target = os.path.dirname(filelink_target)
      missing_link = 'missing link'
  
      def setUp(self):
          assert os.path.exists(self.dirlink_target)
          assert os.path.exists(self.filelink_target)
          assert not os.path.exists(self.dirlink)
          assert not os.path.exists(self.filelink)
          assert not os.path.exists(self.missing_link)
  
      def tearDown(self):
          if os.path.exists(self.filelink):
              os.remove(self.filelink)
          if os.path.exists(self.dirlink):
              os.rmdir(self.dirlink)
          if os.path.lexists(self.missing_link):
              os.remove(self.missing_link)
  
      def test_directory_link(self):
          os.symlink(self.dirlink_target, self.dirlink)
          self.assertTrue(os.path.exists(self.dirlink))
          self.assertTrue(os.path.isdir(self.dirlink))
          self.assertTrue(os.path.islink(self.dirlink))
          self.check_stat(self.dirlink, self.dirlink_target)
  
      def test_file_link(self):
          os.symlink(self.filelink_target, self.filelink)
          self.assertTrue(os.path.exists(self.filelink))
          self.assertTrue(os.path.isfile(self.filelink))
          self.assertTrue(os.path.islink(self.filelink))
          self.check_stat(self.filelink, self.filelink_target)
  
      def _create_missing_dir_link(self):
          'Create a "directory" link to a non-existent target'
          linkname = self.missing_link
          if os.path.lexists(linkname):
              os.remove(linkname)
          target = r'c:\\target does not exist.29r3c740'
          assert not os.path.exists(target)
          target_is_dir = True
          os.symlink(target, linkname, target_is_dir)
  
      def test_remove_directory_link_to_missing_target(self):
          self._create_missing_dir_link()
          # For compatibility with Unix, os.remove will check the
          #  directory status and call RemoveDirectory if the symlink
          #  was created with target_is_dir==True.
          os.remove(self.missing_link)
  
      def test_isdir_on_directory_link_to_missing_target(self):
          self._create_missing_dir_link()
          self.assertFalse(os.path.isdir(self.missing_link))
  
      def test_rmdir_on_directory_link_to_missing_target(self):
          self._create_missing_dir_link()
          os.rmdir(self.missing_link)
  
      def check_stat(self, link, target):
          self.assertEqual(os.stat(link), os.stat(target))
          self.assertNotEqual(os.lstat(link), os.stat(link))
  
          bytes_link = os.fsencode(link)
          self.assertEqual(os.stat(bytes_link), os.stat(target))
          self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
  
      def test_12084(self):
          level1 = os.path.abspath(support.TESTFN)
          level2 = os.path.join(level1, "level2")
          level3 = os.path.join(level2, "level3")
          self.addCleanup(support.rmtree, level1)
  
          os.mkdir(level1)
          os.mkdir(level2)
          os.mkdir(level3)
  
          file1 = os.path.abspath(os.path.join(level1, "file1"))
          create_file(file1)
  
          orig_dir = os.getcwd()
          try:
              os.chdir(level2)
              link = os.path.join(level2, "link")
              os.symlink(os.path.relpath(file1), "link")
              self.assertIn("link", os.listdir(os.getcwd()))
  
              # Check os.stat calls from the same dir as the link
              self.assertEqual(os.stat(file1), os.stat("link"))
  
              # Check os.stat calls from a dir below the link
              os.chdir(level1)
              self.assertEqual(os.stat(file1),
                               os.stat(os.path.relpath(link)))
  
              # Check os.stat calls from a dir above the link
              os.chdir(level3)
              self.assertEqual(os.stat(file1),
                               os.stat(os.path.relpath(link)))
          finally:
              os.chdir(orig_dir)
  
      @unittest.skipUnless(os.path.lexists(r'C:\Users\All Users')
                              and os.path.exists(r'C:\ProgramData'),
                              'Test directories not found')
      def test_29248(self):
          # os.symlink() calls CreateSymbolicLink, which creates
          # the reparse data buffer with the print name stored
          # first, so the offset is always 0. CreateSymbolicLink
          # stores the "PrintName" DOS path (e.g. "C:\") first,
          # with an offset of 0, followed by the "SubstituteName"
          # NT path (e.g. "\??\C:\"). The "All Users" link, on
          # the other hand, seems to have been created manually
          # with an inverted order.
          target = os.readlink(r'C:\Users\All Users')
          self.assertTrue(os.path.samefile(target, r'C:\ProgramData'))
  
      def test_buffer_overflow(self):
          # Older versions would have a buffer overflow when detecting
          # whether a link source was a directory. This test ensures we
          # no longer crash, but does not otherwise validate the behavior
          segment = 'X' * 27
          path = os.path.join(*[segment] * 10)
          test_cases = [
              # overflow with absolute src
              ('\\' + path, segment),
              # overflow dest with relative src
              (segment, path),
              # overflow when joining src
              (path[:180], path[:180]),
          ]
          for src, dest in test_cases:
              try:
                  os.symlink(src, dest)
              except FileNotFoundError:
                  pass
              else:
                  try:
                      os.remove(dest)
                  except OSError:
                      pass
              # Also test with bytes, since that is a separate code path.
              try:
                  os.symlink(os.fsencode(src), os.fsencode(dest))
              except FileNotFoundError:
                  pass
              else:
                  try:
                      os.remove(dest)
                  except OSError:
                      pass
  
      def test_appexeclink(self):
          root = os.path.expandvars(r'%LOCALAPPDATA%\Microsoft\WindowsApps')
          if not os.path.isdir(root):
              self.skipTest("test requires a WindowsApps directory")
  
          aliases = [os.path.join(root, a)
                     for a in fnmatch.filter(os.listdir(root), '*.exe')]
  
          for alias in aliases:
              if support.verbose:
                  print()
                  print("Testing with", alias)
              st = os.lstat(alias)
              self.assertEqual(st, os.stat(alias))
              self.assertFalse(stat.S_ISLNK(st.st_mode))
              self.assertEqual(st.st_reparse_tag, stat.IO_REPARSE_TAG_APPEXECLINK)
              # testing the first one we see is sufficient
              break
          else:
              self.skipTest("test requires an app execution alias")
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32JunctionTests(unittest.TestCase):
      junction = 'junctiontest'
      junction_target = os.path.dirname(os.path.abspath(__file__))
  
      def setUp(self):
          assert os.path.exists(self.junction_target)
          assert not os.path.lexists(self.junction)
  
      def tearDown(self):
          if os.path.lexists(self.junction):
              os.unlink(self.junction)
  
      def test_create_junction(self):
          _winapi.CreateJunction(self.junction_target, self.junction)
          self.assertTrue(os.path.lexists(self.junction))
          self.assertTrue(os.path.exists(self.junction))
          self.assertTrue(os.path.isdir(self.junction))
          self.assertNotEqual(os.stat(self.junction), os.lstat(self.junction))
          self.assertEqual(os.stat(self.junction), os.stat(self.junction_target))
  
          # bpo-37834: Junctions are not recognized as links.
          self.assertFalse(os.path.islink(self.junction))
          self.assertEqual(os.path.normcase("\\\\?\\" + self.junction_target),
                           os.path.normcase(os.readlink(self.junction)))
  
      def test_unlink_removes_junction(self):
          _winapi.CreateJunction(self.junction_target, self.junction)
          self.assertTrue(os.path.exists(self.junction))
          self.assertTrue(os.path.lexists(self.junction))
  
          os.unlink(self.junction)
          self.assertFalse(os.path.exists(self.junction))
  
  @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
  class Win32NtTests(unittest.TestCase):
      def test_getfinalpathname_handles(self):
          nt = support.import_module('nt')
          ctypes = support.import_module('ctypes')
          import ctypes.wintypes
  
          kernel = ctypes.WinDLL('Kernel32.dll', use_last_error=True)
          kernel.GetCurrentProcess.restype = ctypes.wintypes.HANDLE
  
          kernel.GetProcessHandleCount.restype = ctypes.wintypes.BOOL
          kernel.GetProcessHandleCount.argtypes = (ctypes.wintypes.HANDLE,
                                                   ctypes.wintypes.LPDWORD)
  
          # This is a pseudo-handle that doesn't need to be closed
          hproc = kernel.GetCurrentProcess()
  
          handle_count = ctypes.wintypes.DWORD()
          ok = kernel.GetProcessHandleCount(hproc, ctypes.byref(handle_count))
          self.assertEqual(1, ok)
  
          before_count = handle_count.value
  
          # The first two test the error path, __file__ tests the success path
          filenames = [
              r'\\?\C:',
              r'\\?\NUL',
              r'\\?\CONIN',
              __file__,
          ]
  
          for _ in range(10):
              for name in filenames:
                  try:
                      nt._getfinalpathname(name)
                  except Exception:
                      # Failure is expected
                      pass
                  try:
                      os.stat(name)
                  except Exception:
                      pass
  
          ok = kernel.GetProcessHandleCount(hproc, ctypes.byref(handle_count))
          self.assertEqual(1, ok)
  
          handle_delta = handle_count.value - before_count
  
          self.assertEqual(0, handle_delta)
  
  @support.skip_unless_symlink
  class NonLocalSymlinkTests(unittest.TestCase):
  
      def setUp(self):
          r"""
          Create this structure:
  
          base
           \___ some_dir
          """
          os.makedirs('base/some_dir')
  
      def tearDown(self):
          shutil.rmtree('base')
  
      def test_directory_link_nonlocal(self):
          """
          The symlink target should resolve relative to the link, not relative
          to the current directory.
  
          Then, link base/some_link -> base/some_dir and ensure that some_link
          is resolved as a directory.
  
          In issue13772, it was discovered that directory detection failed if
          the symlink target was not specified relative to the current
          directory, which was a defect in the implementation.
          """
          src = os.path.join('base', 'some_link')
          os.symlink('some_dir', src)
          assert os.path.isdir(src)
  
  
  class FSEncodingTests(unittest.TestCase):
      def test_nop(self):
          self.assertEqual(os.fsencode(b'abc\xff'), b'abc\xff')
          self.assertEqual(os.fsdecode('abc\u0141'), 'abc\u0141')
  
      def test_identity(self):
          # assert fsdecode(fsencode(x)) == x
          for fn in ('unicode\u0141', 'latin\xe9', 'ascii'):
              try:
                  bytesfn = os.fsencode(fn)
              except UnicodeEncodeError:
                  continue
              self.assertEqual(os.fsdecode(bytesfn), fn)
  
  
  
  class DeviceEncodingTests(unittest.TestCase):
  
      def test_bad_fd(self):
          # Return None when an fd doesn't actually exist.
          self.assertIsNone(os.device_encoding(123456))
  
      @unittest.skipUnless(os.isatty(0) and not win32_is_iot() and (sys.platform.startswith('win') or
              (hasattr(locale, 'nl_langinfo') and hasattr(locale, 'CODESET'))),
              'test requires a tty and either Windows or nl_langinfo(CODESET)')
      def test_device_encoding(self):
          encoding = os.device_encoding(0)
          self.assertIsNotNone(encoding)
          self.assertTrue(codecs.lookup(encoding))
  
  
  class PidTests(unittest.TestCase):
      @unittest.skipUnless(hasattr(os, 'getppid'), "test needs os.getppid")
      def test_getppid(self):
          p = subprocess.Popen([sys.executable, '-c',
                                'import os; print(os.getppid())'],
                               stdout=subprocess.PIPE)
          stdout, _ = p.communicate()
          # We are the parent of our subprocess
          self.assertEqual(int(stdout), os.getpid())
  
      def test_waitpid(self):
          args = [sys.executable, '-c', 'pass']
          # Add an implicit test for PyUnicode_FSConverter().
          pid = os.spawnv(os.P_NOWAIT, FakePath(args[0]), args)
          status = os.waitpid(pid, 0)
          self.assertEqual(status, (pid, 0))
  
  
  class SpawnTests(unittest.TestCase):
      def create_args(self, *, with_env=False, use_bytes=False):
          self.exitcode = 17
  
          filename = support.TESTFN
          self.addCleanup(support.unlink, filename)
  
          if not with_env:
              code = 'import sys; sys.exit(%s)' % self.exitcode
          else:
              self.env = dict(os.environ)
              # create an unique key
              self.key = str(uuid.uuid4())
              self.env[self.key] = self.key
              # read the variable from os.environ to check that it exists
              code = ('import sys, os; magic = os.environ[%r]; sys.exit(%s)'
                      % (self.key, self.exitcode))
  
          with open(filename, "w") as fp:
              fp.write(code)
  
          args = [sys.executable, filename]
          if use_bytes:
              args = [os.fsencode(a) for a in args]
              self.env = {os.fsencode(k): os.fsencode(v)
                          for k, v in self.env.items()}
  
          return args
  
      @requires_os_func('spawnl')
      def test_spawnl(self):
          args = self.create_args()
          exitcode = os.spawnl(os.P_WAIT, args[0], *args)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnle')
      def test_spawnle(self):
          args = self.create_args(with_env=True)
          exitcode = os.spawnle(os.P_WAIT, args[0], *args, self.env)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnlp')
      def test_spawnlp(self):
          args = self.create_args()
          exitcode = os.spawnlp(os.P_WAIT, args[0], *args)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnlpe')
      def test_spawnlpe(self):
          args = self.create_args(with_env=True)
          exitcode = os.spawnlpe(os.P_WAIT, args[0], *args, self.env)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnv')
      def test_spawnv(self):
          args = self.create_args()
          exitcode = os.spawnv(os.P_WAIT, args[0], args)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnve')
      def test_spawnve(self):
          args = self.create_args(with_env=True)
          exitcode = os.spawnve(os.P_WAIT, args[0], args, self.env)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnvp')
      def test_spawnvp(self):
          args = self.create_args()
          exitcode = os.spawnvp(os.P_WAIT, args[0], args)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnvpe')
      def test_spawnvpe(self):
          args = self.create_args(with_env=True)
          exitcode = os.spawnvpe(os.P_WAIT, args[0], args, self.env)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnv')
      def test_nowait(self):
          args = self.create_args()
          pid = os.spawnv(os.P_NOWAIT, args[0], args)
          result = os.waitpid(pid, 0)
          self.assertEqual(result[0], pid)
          status = result[1]
          if hasattr(os, 'WIFEXITED'):
              self.assertTrue(os.WIFEXITED(status))
              self.assertEqual(os.WEXITSTATUS(status), self.exitcode)
          else:
              self.assertEqual(status, self.exitcode << 8)
  
      @requires_os_func('spawnve')
      def test_spawnve_bytes(self):
          # Test bytes handling in parse_arglist and parse_envlist (#28114)
          args = self.create_args(with_env=True, use_bytes=True)
          exitcode = os.spawnve(os.P_WAIT, args[0], args, self.env)
          self.assertEqual(exitcode, self.exitcode)
  
      @requires_os_func('spawnl')
      def test_spawnl_noargs(self):
          args = self.create_args()
          self.assertRaises(ValueError, os.spawnl, os.P_NOWAIT, args[0])
          self.assertRaises(ValueError, os.spawnl, os.P_NOWAIT, args[0], '')
  
      @requires_os_func('spawnle')
      def test_spawnle_noargs(self):
          args = self.create_args()
          self.assertRaises(ValueError, os.spawnle, os.P_NOWAIT, args[0], {})
          self.assertRaises(ValueError, os.spawnle, os.P_NOWAIT, args[0], '', {})
  
      @requires_os_func('spawnv')
      def test_spawnv_noargs(self):
          args = self.create_args()
          self.assertRaises(ValueError, os.spawnv, os.P_NOWAIT, args[0], ())
          self.assertRaises(ValueError, os.spawnv, os.P_NOWAIT, args[0], [])
          self.assertRaises(ValueError, os.spawnv, os.P_NOWAIT, args[0], ('',))
          self.assertRaises(ValueError, os.spawnv, os.P_NOWAIT, args[0], [''])
  
      @requires_os_func('spawnve')
      def test_spawnve_noargs(self):
          args = self.create_args()
          self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, args[0], (), {})
          self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, args[0], [], {})
          self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, args[0], ('',), {})
          self.assertRaises(ValueError, os.spawnve, os.P_NOWAIT, args[0], [''], {})
  
      def _test_invalid_env(self, spawn):
          args = [sys.executable, '-c', 'pass']
  
          # null character in the environment variable name
          newenv = os.environ.copy()
          newenv["FRUIT\0VEGETABLE"] = "cabbage"
          try:
              exitcode = spawn(os.P_WAIT, args[0], args, newenv)
          except ValueError:
              pass
          else:
              self.assertEqual(exitcode, 127)
  
          # null character in the environment variable value
          newenv = os.environ.copy()
          newenv["FRUIT"] = "orange\0VEGETABLE=cabbage"
          try:
              exitcode = spawn(os.P_WAIT, args[0], args, newenv)
          except ValueError:
              pass
          else:
              self.assertEqual(exitcode, 127)
  
          # equal character in the environment variable name
          newenv = os.environ.copy()
          newenv["FRUIT=ORANGE"] = "lemon"
          try:
              exitcode = spawn(os.P_WAIT, args[0], args, newenv)
          except ValueError:
              pass
          else:
              self.assertEqual(exitcode, 127)
  
          # equal character in the environment variable value
          filename = support.TESTFN
          self.addCleanup(support.unlink, filename)
          with open(filename, "w") as fp:
              fp.write('import sys, os\n'
                       'if os.getenv("FRUIT") != "orange=lemon":\n'
                       '    raise AssertionError')
          args = [sys.executable, filename]
          newenv = os.environ.copy()
          newenv["FRUIT"] = "orange=lemon"
          exitcode = spawn(os.P_WAIT, args[0], args, newenv)
          self.assertEqual(exitcode, 0)
  
      @requires_os_func('spawnve')
      def test_spawnve_invalid_env(self):
          self._test_invalid_env(os.spawnve)
  
      @requires_os_func('spawnvpe')
      def test_spawnvpe_invalid_env(self):
          self._test_invalid_env(os.spawnvpe)
  
  
  # The introduction of this TestCase caused at least two different errors on
  # *nix buildbots. Temporarily skip this to let the buildbots move along.
  @unittest.skip("Skip due to platform/environment differences on *NIX buildbots")
  @unittest.skipUnless(hasattr(os, 'getlogin'), "test needs os.getlogin")
  class LoginTests(unittest.TestCase):
      def test_getlogin(self):
          user_name = os.getlogin()
          self.assertNotEqual(len(user_name), 0)
  
  
  @unittest.skipUnless(hasattr(os, 'getpriority') and hasattr(os, 'setpriority'),
                       "needs os.getpriority and os.setpriority")
  class ProgramPriorityTests(unittest.TestCase):
      """Tests for os.getpriority() and os.setpriority()."""
  
      def test_set_get_priority(self):
  
          base = os.getpriority(os.PRIO_PROCESS, os.getpid())
          os.setpriority(os.PRIO_PROCESS, os.getpid(), base + 1)
          try:
              new_prio = os.getpriority(os.PRIO_PROCESS, os.getpid())
              if base >= 19 and new_prio <= 19:
                  raise unittest.SkipTest("unable to reliably test setpriority "
                                          "at current nice level of %s" % base)
              else:
                  self.assertEqual(new_prio, base + 1)
          finally:
              try:
                  os.setpriority(os.PRIO_PROCESS, os.getpid(), base)
              except OSError as err:
                  if err.errno != errno.EACCES:
                      raise
  
  
  class SendfileTestServer(asyncore.dispatcher, threading.Thread):
  
      class Handler(asynchat.async_chat):
  
          def __init__(self, conn):
              asynchat.async_chat.__init__(self, conn)
              self.in_buffer = []
              self.accumulate = True
              self.closed = False
              self.push(b"220 ready\r\n")
  
          def handle_read(self):
              data = self.recv(4096)
              if self.accumulate:
                  self.in_buffer.append(data)
  
          def get_data(self):
              return b''.join(self.in_buffer)
  
          def handle_close(self):
              self.close()
              self.closed = True
  
          def handle_error(self):
              raise
  
      def __init__(self, address):
          threading.Thread.__init__(self)
          asyncore.dispatcher.__init__(self)
          self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
          self.bind(address)
          self.listen(5)
          self.host, self.port = self.socket.getsockname()[:2]
          self.handler_instance = None
          self._active = False
          self._active_lock = threading.Lock()
  
      # --- public API
  
      @property
      def running(self):
          return self._active
  
      def start(self):
          assert not self.running
          self.__flag = threading.Event()
          threading.Thread.start(self)
          self.__flag.wait()
  
      def stop(self):
          assert self.running
          self._active = False
          self.join()
  
      def wait(self):
          # wait for handler connection to be closed, then stop the server
          while not getattr(self.handler_instance, "closed", False):
              time.sleep(0.001)
          self.stop()
  
      # --- internals
  
      def run(self):
          self._active = True
          self.__flag.set()
          while self._active and asyncore.socket_map:
              self._active_lock.acquire()
              asyncore.loop(timeout=0.001, count=1)
              self._active_lock.release()
          asyncore.close_all()
  
      def handle_accept(self):
          conn, addr = self.accept()
          self.handler_instance = self.Handler(conn)
  
      def handle_connect(self):
          self.close()
      handle_read = handle_connect
  
      def writable(self):
          return 0
  
      def handle_error(self):
          raise
  
  
  @unittest.skipUnless(hasattr(os, 'sendfile'), "test needs os.sendfile()")
  class TestSendfile(unittest.TestCase):
  
      DATA = b"12345abcde" * 16 * 1024  # 160 KiB
      SUPPORT_HEADERS_TRAILERS = not sys.platform.startswith("linux") and \
                                 not sys.platform.startswith("solaris") and \
                                 not sys.platform.startswith("sunos")
      requires_headers_trailers = unittest.skipUnless(SUPPORT_HEADERS_TRAILERS,
              'requires headers and trailers support')
      requires_32b = unittest.skipUnless(sys.maxsize < 2**32,
              'test is only meaningful on 32-bit builds')
  
      @classmethod
      def setUpClass(cls):
          cls.key = support.threading_setup()
          create_file(support.TESTFN, cls.DATA)
  
      @classmethod
      def tearDownClass(cls):
          support.threading_cleanup(*cls.key)
          support.unlink(support.TESTFN)
  
      def setUp(self):
          self.server = SendfileTestServer((support.HOST, 0))
          self.server.start()
          self.client = socket.socket()
          self.client.connect((self.server.host, self.server.port))
          self.client.settimeout(1)
          # synchronize by waiting for "220 ready" response
          self.client.recv(1024)
          self.sockno = self.client.fileno()
          self.file = open(support.TESTFN, 'rb')
          self.fileno = self.file.fileno()
  
      def tearDown(self):
          self.file.close()
          self.client.close()
          if self.server.running:
              self.server.stop()
          self.server = None
  
      def sendfile_wrapper(self, *args, **kwargs):
          """A higher level wrapper representing how an application is
          supposed to use sendfile().
          """
          while True:
              try:
                  return os.sendfile(*args, **kwargs)
              except OSError as err:
                  if err.errno == errno.ECONNRESET:
                      # disconnected
                      raise
                  elif err.errno in (errno.EAGAIN, errno.EBUSY):
                      # we have to retry send data
                      continue
                  else:
                      raise
  
      def test_send_whole_file(self):
          # normal send
          total_sent = 0
          offset = 0
          nbytes = 4096
          while total_sent < len(self.DATA):
              sent = self.sendfile_wrapper(self.sockno, self.fileno, offset, nbytes)
              if sent == 0:
                  break
              offset += sent
              total_sent += sent
              self.assertTrue(sent <= nbytes)
              self.assertEqual(offset, total_sent)
  
          self.assertEqual(total_sent, len(self.DATA))
          self.client.shutdown(socket.SHUT_RDWR)
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          self.assertEqual(len(data), len(self.DATA))
          self.assertEqual(data, self.DATA)
  
      def test_send_at_certain_offset(self):
          # start sending a file at a certain offset
          total_sent = 0
          offset = len(self.DATA) // 2
          must_send = len(self.DATA) - offset
          nbytes = 4096
          while total_sent < must_send:
              sent = self.sendfile_wrapper(self.sockno, self.fileno, offset, nbytes)
              if sent == 0:
                  break
              offset += sent
              total_sent += sent
              self.assertTrue(sent <= nbytes)
  
          self.client.shutdown(socket.SHUT_RDWR)
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          expected = self.DATA[len(self.DATA) // 2:]
          self.assertEqual(total_sent, len(expected))
          self.assertEqual(len(data), len(expected))
          self.assertEqual(data, expected)
  
      def test_offset_overflow(self):
          # specify an offset > file size
          offset = len(self.DATA) + 4096
          try:
              sent = os.sendfile(self.sockno, self.fileno, offset, 4096)
          except OSError as e:
              # Solaris can raise EINVAL if offset >= file length, ignore.
              if e.errno != errno.EINVAL:
                  raise
          else:
              self.assertEqual(sent, 0)
          self.client.shutdown(socket.SHUT_RDWR)
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          self.assertEqual(data, b'')
  
      def test_invalid_offset(self):
          with self.assertRaises(OSError) as cm:
              os.sendfile(self.sockno, self.fileno, -1, 4096)
          self.assertEqual(cm.exception.errno, errno.EINVAL)
  
      def test_keywords(self):
          # Keyword arguments should be supported
          os.sendfile(out_fd=self.sockno, in_fd=self.fileno,
                      offset=0, count=4096)
          if self.SUPPORT_HEADERS_TRAILERS:
              os.sendfile(out_fd=self.sockno, in_fd=self.fileno,
                          offset=0, count=4096,
                          headers=(), trailers=(), flags=0)
  
      # --- headers / trailers tests
  
      @requires_headers_trailers
      def test_headers(self):
          total_sent = 0
          expected_data = b"x" * 512 + b"y" * 256 + self.DATA[:-1]
          sent = os.sendfile(self.sockno, self.fileno, 0, 4096,
                              headers=[b"x" * 512, b"y" * 256])
          self.assertLessEqual(sent, 512 + 256 + 4096)
          total_sent += sent
          offset = 4096
          while total_sent < len(expected_data):
              nbytes = min(len(expected_data) - total_sent, 4096)
              sent = self.sendfile_wrapper(self.sockno, self.fileno,
                                                      offset, nbytes)
              if sent == 0:
                  break
              self.assertLessEqual(sent, nbytes)
              total_sent += sent
              offset += sent
  
          self.assertEqual(total_sent, len(expected_data))
          self.client.close()
          self.server.wait()
          data = self.server.handler_instance.get_data()
          self.assertEqual(hash(data), hash(expected_data))
  
      @requires_headers_trailers
      def test_trailers(self):
          TESTFN2 = support.TESTFN + "2"
          file_data = b"abcdef"
  
          self.addCleanup(support.unlink, TESTFN2)
          create_file(TESTFN2, file_data)
  
          with open(TESTFN2, 'rb') as f:
              os.sendfile(self.sockno, f.fileno(), 0, 5,
                          trailers=[b"123456", b"789"])
              self.client.close()
              self.server.wait()
              data = self.server.handler_instance.get_data()
              self.assertEqual(data, b"abcde123456789")
  
      @requires_headers_trailers
      @requires_32b
      def test_headers_overflow_32bits(self):
          self.server.handler_instance.accumulate = False
          with self.assertRaises(OSError) as cm:
              os.sendfile(self.sockno, self.fileno, 0, 0,
                          headers=[b"x" * 2**16] * 2**15)
          self.assertEqual(cm.exception.errno, errno.EINVAL)
  
      @requires_headers_trailers
      @requires_32b
      def test_trailers_overflow_32bits(self):
          self.server.handler_instance.accumulate = False
          with self.assertRaises(OSError) as cm:
              os.sendfile(self.sockno, self.fileno, 0, 0,
                          trailers=[b"x" * 2**16] * 2**15)
          self.assertEqual(cm.exception.errno, errno.EINVAL)
  
      @requires_headers_trailers
      @unittest.skipUnless(hasattr(os, 'SF_NODISKIO'),
                           'test needs os.SF_NODISKIO')
      def test_flags(self):
          try:
              os.sendfile(self.sockno, self.fileno, 0, 4096,
                          flags=os.SF_NODISKIO)
          except OSError as err:
              if err.errno not in (errno.EBUSY, errno.EAGAIN):
                  raise
  
  
  def supports_extended_attributes():
      if not hasattr(os, "setxattr"):
          return False
  
      try:
          with open(support.TESTFN, "xb", 0) as fp:
              try:
                  os.setxattr(fp.fileno(), b"user.test", b"")
              except OSError:
                  return False
      finally:
          support.unlink(support.TESTFN)
  
      return True
  
  
  @unittest.skipUnless(supports_extended_attributes(),
                       "no non-broken extended attribute support")
  # Kernels < 2.6.39 don't respect setxattr flags.
  @support.requires_linux_version(2, 6, 39)
  class ExtendedAttributeTests(unittest.TestCase):
  
      def _check_xattrs_str(self, s, getxattr, setxattr, removexattr, listxattr, **kwargs):
          fn = support.TESTFN
          self.addCleanup(support.unlink, fn)
          create_file(fn)
  
          with self.assertRaises(OSError) as cm:
              getxattr(fn, s("user.test"), **kwargs)
          self.assertEqual(cm.exception.errno, errno.ENODATA)
  
          init_xattr = listxattr(fn)
          self.assertIsInstance(init_xattr, list)
  
          setxattr(fn, s("user.test"), b"", **kwargs)
          xattr = set(init_xattr)
          xattr.add("user.test")
          self.assertEqual(set(listxattr(fn)), xattr)
          self.assertEqual(getxattr(fn, b"user.test", **kwargs), b"")
          setxattr(fn, s("user.test"), b"hello", os.XATTR_REPLACE, **kwargs)
          self.assertEqual(getxattr(fn, b"user.test", **kwargs), b"hello")
  
          with self.assertRaises(OSError) as cm:
              setxattr(fn, s("user.test"), b"bye", os.XATTR_CREATE, **kwargs)
          self.assertEqual(cm.exception.errno, errno.EEXIST)
  
          with self.assertRaises(OSError) as cm:
              setxattr(fn, s("user.test2"), b"bye", os.XATTR_REPLACE, **kwargs)
          self.assertEqual(cm.exception.errno, errno.ENODATA)
  
          setxattr(fn, s("user.test2"), b"foo", os.XATTR_CREATE, **kwargs)
          xattr.add("user.test2")
          self.assertEqual(set(listxattr(fn)), xattr)
          removexattr(fn, s("user.test"), **kwargs)
  
          with self.assertRaises(OSError) as cm:
              getxattr(fn, s("user.test"), **kwargs)
          self.assertEqual(cm.exception.errno, errno.ENODATA)
  
          xattr.remove("user.test")
          self.assertEqual(set(listxattr(fn)), xattr)
          self.assertEqual(getxattr(fn, s("user.test2"), **kwargs), b"foo")
          setxattr(fn, s("user.test"), b"a"*1024, **kwargs)
          self.assertEqual(getxattr(fn, s("user.test"), **kwargs), b"a"*1024)
          removexattr(fn, s("user.test"), **kwargs)
          many = sorted("user.test{}".format(i) for i in range(100))
          for thing in many:
              setxattr(fn, thing, b"x", **kwargs)
          self.assertEqual(set(listxattr(fn)), set(init_xattr) | set(many))
  
      def _check_xattrs(self, *args, **kwargs):
          self._check_xattrs_str(str, *args, **kwargs)
          support.unlink(support.TESTFN)
  
          self._check_xattrs_str(os.fsencode, *args, **kwargs)
          support.unlink(support.TESTFN)
  
      def test_simple(self):
          self._check_xattrs(os.getxattr, os.setxattr, os.removexattr,
                             os.listxattr)
  
      def test_lpath(self):
          self._check_xattrs(os.getxattr, os.setxattr, os.removexattr,
                             os.listxattr, follow_symlinks=False)
  
      def test_fds(self):
          def getxattr(path, *args):
              with open(path, "rb") as fp:
                  return os.getxattr(fp.fileno(), *args)
          def setxattr(path, *args):
              with open(path, "wb", 0) as fp:
                  os.setxattr(fp.fileno(), *args)
          def removexattr(path, *args):
              with open(path, "wb", 0) as fp:
                  os.removexattr(fp.fileno(), *args)
          def listxattr(path, *args):
              with open(path, "rb") as fp:
                  return os.listxattr(fp.fileno(), *args)
          self._check_xattrs(getxattr, setxattr, removexattr, listxattr)
  
  
  @unittest.skipUnless(hasattr(os, 'get_terminal_size'), "requires os.get_terminal_size")
  class TermsizeTests(unittest.TestCase):
      def test_does_not_crash(self):
          """Check if get_terminal_size() returns a meaningful value.
  
          There's no easy portable way to actually check the size of the
          terminal, so let's check if it returns something sensible instead.
          """
          try:
              size = os.get_terminal_size()
          except OSError as e:
              if sys.platform == "win32" or e.errno in (errno.EINVAL, errno.ENOTTY):
                  # Under win32 a generic OSError can be thrown if the
                  # handle cannot be retrieved
                  self.skipTest("failed to query terminal size")
              raise
  
          self.assertGreaterEqual(size.columns, 0)
          self.assertGreaterEqual(size.lines, 0)
  
      def test_stty_match(self):
          """Check if stty returns the same results
  
          stty actually tests stdin, so get_terminal_size is invoked on
          stdin explicitly. If stty succeeded, then get_terminal_size()
          should work too.
          """
          try:
              size = subprocess.check_output(['stty', 'size']).decode().split()
          except (FileNotFoundError, subprocess.CalledProcessError,
                  PermissionError):
              self.skipTest("stty invocation failed")
          expected = (int(size[1]), int(size[0])) # reversed order
  
          try:
              actual = os.get_terminal_size(sys.__stdin__.fileno())
          except OSError as e:
              if sys.platform == "win32" or e.errno in (errno.EINVAL, errno.ENOTTY):
                  # Under win32 a generic OSError can be thrown if the
                  # handle cannot be retrieved
                  self.skipTest("failed to query terminal size")
              raise
          self.assertEqual(expected, actual)
  
  
  @unittest.skipUnless(hasattr(os, 'memfd_create'), 'requires os.memfd_create')
  @support.requires_linux_version(3, 17)
  class MemfdCreateTests(unittest.TestCase):
      def test_memfd_create(self):
          fd = os.memfd_create("Hi", os.MFD_CLOEXEC)
          self.assertNotEqual(fd, -1)
          self.addCleanup(os.close, fd)
          self.assertFalse(os.get_inheritable(fd))
          with open(fd, "wb", closefd=False) as f:
              f.write(b'memfd_create')
              self.assertEqual(f.tell(), 12)
  
          fd2 = os.memfd_create("Hi")
          self.addCleanup(os.close, fd2)
          self.assertFalse(os.get_inheritable(fd2))
  
  
  class OSErrorTests(unittest.TestCase):
      def setUp(self):
          class Str(str):
              pass
  
          self.bytes_filenames = []
          self.unicode_filenames = []
          if support.TESTFN_UNENCODABLE is not None:
              decoded = support.TESTFN_UNENCODABLE
          else:
              decoded = support.TESTFN
          self.unicode_filenames.append(decoded)
          self.unicode_filenames.append(Str(decoded))
          if support.TESTFN_UNDECODABLE is not None:
              encoded = support.TESTFN_UNDECODABLE
          else:
              encoded = os.fsencode(support.TESTFN)
          self.bytes_filenames.append(encoded)
          self.bytes_filenames.append(bytearray(encoded))
          self.bytes_filenames.append(memoryview(encoded))
  
          self.filenames = self.bytes_filenames + self.unicode_filenames
  
      def test_oserror_filename(self):
          funcs = [
              (self.filenames, os.chdir,),
              (self.filenames, os.chmod, 0o777),
              (self.filenames, os.lstat,),
              (self.filenames, os.open, os.O_RDONLY),
              (self.filenames, os.rmdir,),
              (self.filenames, os.stat,),
              (self.filenames, os.unlink,),
          ]
          if sys.platform == "win32":
              funcs.extend((
                  (self.bytes_filenames, os.rename, b"dst"),
                  (self.bytes_filenames, os.replace, b"dst"),
                  (self.unicode_filenames, os.rename, "dst"),
                  (self.unicode_filenames, os.replace, "dst"),
                  (self.unicode_filenames, os.listdir, ),
              ))
          else:
              funcs.extend((
                  (self.filenames, os.listdir,),
                  (self.filenames, os.rename, "dst"),
                  (self.filenames, os.replace, "dst"),
              ))
          if hasattr(os, "chown"):
              funcs.append((self.filenames, os.chown, 0, 0))
          if hasattr(os, "lchown"):
              funcs.append((self.filenames, os.lchown, 0, 0))
          if hasattr(os, "truncate"):
              funcs.append((self.filenames, os.truncate, 0))
          if hasattr(os, "chflags"):
              funcs.append((self.filenames, os.chflags, 0))
          if hasattr(os, "lchflags"):
              funcs.append((self.filenames, os.lchflags, 0))
          if hasattr(os, "chroot"):
              funcs.append((self.filenames, os.chroot,))
          if hasattr(os, "link"):
              if sys.platform == "win32":
                  funcs.append((self.bytes_filenames, os.link, b"dst"))
                  funcs.append((self.unicode_filenames, os.link, "dst"))
              else:
                  funcs.append((self.filenames, os.link, "dst"))
          if hasattr(os, "listxattr"):
              funcs.extend((
                  (self.filenames, os.listxattr,),
                  (self.filenames, os.getxattr, "user.test"),
                  (self.filenames, os.setxattr, "user.test", b'user'),
                  (self.filenames, os.removexattr, "user.test"),
              ))
          if hasattr(os, "lchmod"):
              funcs.append((self.filenames, os.lchmod, 0o777))
          if hasattr(os, "readlink"):
              funcs.append((self.filenames, os.readlink,))
  
  
          for filenames, func, *func_args in funcs:
              for name in filenames:
                  try:
                      if isinstance(name, (str, bytes)):
                          func(name, *func_args)
                      else:
                          with self.assertWarnsRegex(DeprecationWarning, 'should be'):
                              func(name, *func_args)
                  except OSError as err:
                      self.assertIs(err.filename, name, str(func))
                  except UnicodeDecodeError:
                      pass
                  else:
                      self.fail("No exception thrown by {}".format(func))
  
  class CPUCountTests(unittest.TestCase):
      def test_cpu_count(self):
          cpus = os.cpu_count()
          if cpus is not None:
              self.assertIsInstance(cpus, int)
              self.assertGreater(cpus, 0)
          else:
              self.skipTest("Could not determine the number of CPUs")
  
  
  class FDInheritanceTests(unittest.TestCase):
      def test_get_set_inheritable(self):
          fd = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd)
          self.assertEqual(os.get_inheritable(fd), False)
  
          os.set_inheritable(fd, True)
          self.assertEqual(os.get_inheritable(fd), True)
  
      @unittest.skipIf(fcntl is None, "need fcntl")
      def test_get_inheritable_cloexec(self):
          fd = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd)
          self.assertEqual(os.get_inheritable(fd), False)
  
          # clear FD_CLOEXEC flag
          flags = fcntl.fcntl(fd, fcntl.F_GETFD)
          flags &= ~fcntl.FD_CLOEXEC
          fcntl.fcntl(fd, fcntl.F_SETFD, flags)
  
          self.assertEqual(os.get_inheritable(fd), True)
  
      @unittest.skipIf(fcntl is None, "need fcntl")
      def test_set_inheritable_cloexec(self):
          fd = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd)
          self.assertEqual(fcntl.fcntl(fd, fcntl.F_GETFD) & fcntl.FD_CLOEXEC,
                           fcntl.FD_CLOEXEC)
  
          os.set_inheritable(fd, True)
          self.assertEqual(fcntl.fcntl(fd, fcntl.F_GETFD) & fcntl.FD_CLOEXEC,
                           0)
  
      def test_open(self):
          fd = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd)
          self.assertEqual(os.get_inheritable(fd), False)
  
      @unittest.skipUnless(hasattr(os, 'pipe'), "need os.pipe()")
      def test_pipe(self):
          rfd, wfd = os.pipe()
          self.addCleanup(os.close, rfd)
          self.addCleanup(os.close, wfd)
          self.assertEqual(os.get_inheritable(rfd), False)
          self.assertEqual(os.get_inheritable(wfd), False)
  
      def test_dup(self):
          fd1 = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd1)
  
          fd2 = os.dup(fd1)
          self.addCleanup(os.close, fd2)
          self.assertEqual(os.get_inheritable(fd2), False)
  
      def test_dup_standard_stream(self):
          fd = os.dup(1)
          self.addCleanup(os.close, fd)
          self.assertGreater(fd, 0)
  
      @unittest.skipUnless(sys.platform == 'win32', 'win32-specific test')
      def test_dup_nul(self):
          # os.dup() was creating inheritable fds for character files.
          fd1 = os.open('NUL', os.O_RDONLY)
          self.addCleanup(os.close, fd1)
          fd2 = os.dup(fd1)
          self.addCleanup(os.close, fd2)
          self.assertFalse(os.get_inheritable(fd2))
  
      @unittest.skipUnless(hasattr(os, 'dup2'), "need os.dup2()")
      def test_dup2(self):
          fd = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd)
  
          # inheritable by default
          fd2 = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd2)
          self.assertEqual(os.dup2(fd, fd2), fd2)
          self.assertTrue(os.get_inheritable(fd2))
  
          # force non-inheritable
          fd3 = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd3)
          self.assertEqual(os.dup2(fd, fd3, inheritable=False), fd3)
          self.assertFalse(os.get_inheritable(fd3))
  
      @unittest.skipUnless(hasattr(os, 'openpty'), "need os.openpty()")
      def test_openpty(self):
          master_fd, slave_fd = os.openpty()
          self.addCleanup(os.close, master_fd)
          self.addCleanup(os.close, slave_fd)
          self.assertEqual(os.get_inheritable(master_fd), False)
          self.assertEqual(os.get_inheritable(slave_fd), False)
  
  
  class PathTConverterTests(unittest.TestCase):
      # tuples of (function name, allows fd arguments, additional arguments to
      # function, cleanup function)
      functions = [
          ('stat', True, (), None),
          ('lstat', False, (), None),
          ('access', False, (os.F_OK,), None),
          ('chflags', False, (0,), None),
          ('lchflags', False, (0,), None),
          ('open', False, (0,), getattr(os, 'close', None)),
      ]
  
      def test_path_t_converter(self):
          str_filename = support.TESTFN
          if os.name == 'nt':
              bytes_fspath = bytes_filename = None
          else:
              bytes_filename = support.TESTFN.encode('ascii')
              bytes_fspath = FakePath(bytes_filename)
          fd = os.open(FakePath(str_filename), os.O_WRONLY|os.O_CREAT)
          self.addCleanup(support.unlink, support.TESTFN)
          self.addCleanup(os.close, fd)
  
          int_fspath = FakePath(fd)
          str_fspath = FakePath(str_filename)
  
          for name, allow_fd, extra_args, cleanup_fn in self.functions:
              with self.subTest(name=name):
                  try:
                      fn = getattr(os, name)
                  except AttributeError:
                      continue
  
                  for path in (str_filename, bytes_filename, str_fspath,
                               bytes_fspath):
                      if path is None:
                          continue
                      with self.subTest(name=name, path=path):
                          result = fn(path, *extra_args)
                          if cleanup_fn is not None:
                              cleanup_fn(result)
  
                  with self.assertRaisesRegex(
                          TypeError, 'to return str or bytes'):
                      fn(int_fspath, *extra_args)
  
                  if allow_fd:
                      result = fn(fd, *extra_args)  # should not fail
                      if cleanup_fn is not None:
                          cleanup_fn(result)
                  else:
                      with self.assertRaisesRegex(
                              TypeError,
                              'os.PathLike'):
                          fn(fd, *extra_args)
  
      def test_path_t_converter_and_custom_class(self):
          msg = r'__fspath__\(\) to return str or bytes, not %s'
          with self.assertRaisesRegex(TypeError, msg % r'int'):
              os.stat(FakePath(2))
          with self.assertRaisesRegex(TypeError, msg % r'float'):
              os.stat(FakePath(2.34))
          with self.assertRaisesRegex(TypeError, msg % r'object'):
              os.stat(FakePath(object()))
  
  
  @unittest.skipUnless(hasattr(os, 'get_blocking'),
                       'needs os.get_blocking() and os.set_blocking()')
  class BlockingTests(unittest.TestCase):
      def test_blocking(self):
          fd = os.open(__file__, os.O_RDONLY)
          self.addCleanup(os.close, fd)
          self.assertEqual(os.get_blocking(fd), True)
  
          os.set_blocking(fd, False)
          self.assertEqual(os.get_blocking(fd), False)
  
          os.set_blocking(fd, True)
          self.assertEqual(os.get_blocking(fd), True)
  
  
  
  class ExportsTests(unittest.TestCase):
      def test_os_all(self):
          self.assertIn('open', os.__all__)
          self.assertIn('walk', os.__all__)
  
  
  class TestScandir(unittest.TestCase):
      check_no_resource_warning = support.check_no_resource_warning
  
      def setUp(self):
          self.path = os.path.realpath(support.TESTFN)
          self.bytes_path = os.fsencode(self.path)
          self.addCleanup(support.rmtree, self.path)
          os.mkdir(self.path)
  
      def create_file(self, name="file.txt"):
          path = self.bytes_path if isinstance(name, bytes) else self.path
          filename = os.path.join(path, name)
          create_file(filename, b'python')
          return filename
  
      def get_entries(self, names):
          entries = dict((entry.name, entry)
                         for entry in os.scandir(self.path))
          self.assertEqual(sorted(entries.keys()), names)
          return entries
  
      def assert_stat_equal(self, stat1, stat2, skip_fields):
          if skip_fields:
              for attr in dir(stat1):
                  if not attr.startswith("st_"):
                      continue
                  if attr in ("st_dev", "st_ino", "st_nlink"):
                      continue
                  self.assertEqual(getattr(stat1, attr),
                                   getattr(stat2, attr),
                                   (stat1, stat2, attr))
          else:
              self.assertEqual(stat1, stat2)
  
      def check_entry(self, entry, name, is_dir, is_file, is_symlink):
          self.assertIsInstance(entry, os.DirEntry)
          self.assertEqual(entry.name, name)
          self.assertEqual(entry.path, os.path.join(self.path, name))
          self.assertEqual(entry.inode(),
                           os.stat(entry.path, follow_symlinks=False).st_ino)
  
          entry_stat = os.stat(entry.path)
          self.assertEqual(entry.is_dir(),
                           stat.S_ISDIR(entry_stat.st_mode))
          self.assertEqual(entry.is_file(),
                           stat.S_ISREG(entry_stat.st_mode))
          self.assertEqual(entry.is_symlink(),
                           os.path.islink(entry.path))
  
          entry_lstat = os.stat(entry.path, follow_symlinks=False)
          self.assertEqual(entry.is_dir(follow_symlinks=False),
                           stat.S_ISDIR(entry_lstat.st_mode))
          self.assertEqual(entry.is_file(follow_symlinks=False),
                           stat.S_ISREG(entry_lstat.st_mode))
  
          self.assert_stat_equal(entry.stat(),
                                 entry_stat,
                                 os.name == 'nt' and not is_symlink)
          self.assert_stat_equal(entry.stat(follow_symlinks=False),
                                 entry_lstat,
                                 os.name == 'nt')
  
      def test_attributes(self):
          link = hasattr(os, 'link')
          symlink = support.can_symlink()
  
          dirname = os.path.join(self.path, "dir")
          os.mkdir(dirname)
          filename = self.create_file("file.txt")
          if link:
              try:
                  os.link(filename, os.path.join(self.path, "link_file.txt"))
              except PermissionError as e:
                  self.skipTest('os.link(): %s' % e)
          if symlink:
              os.symlink(dirname, os.path.join(self.path, "symlink_dir"),
                         target_is_directory=True)
              os.symlink(filename, os.path.join(self.path, "symlink_file.txt"))
  
          names = ['dir', 'file.txt']
          if link:
              names.append('link_file.txt')
          if symlink:
              names.extend(('symlink_dir', 'symlink_file.txt'))
          entries = self.get_entries(names)
  
          entry = entries['dir']
          self.check_entry(entry, 'dir', True, False, False)
  
          entry = entries['file.txt']
          self.check_entry(entry, 'file.txt', False, True, False)
  
          if link:
              entry = entries['link_file.txt']
              self.check_entry(entry, 'link_file.txt', False, True, False)
  
          if symlink:
              entry = entries['symlink_dir']
              self.check_entry(entry, 'symlink_dir', True, False, True)
  
              entry = entries['symlink_file.txt']
              self.check_entry(entry, 'symlink_file.txt', False, True, True)
  
      def get_entry(self, name):
          path = self.bytes_path if isinstance(name, bytes) else self.path
          entries = list(os.scandir(path))
          self.assertEqual(len(entries), 1)
  
          entry = entries[0]
          self.assertEqual(entry.name, name)
          return entry
  
      def create_file_entry(self, name='file.txt'):
          filename = self.create_file(name=name)
          return self.get_entry(os.path.basename(filename))
  
      def test_current_directory(self):
          filename = self.create_file()
          old_dir = os.getcwd()
          try:
              os.chdir(self.path)
  
              # call scandir() without parameter: it must list the content
              # of the current directory
              entries = dict((entry.name, entry) for entry in os.scandir())
              self.assertEqual(sorted(entries.keys()),
                               [os.path.basename(filename)])
          finally:
              os.chdir(old_dir)
  
      def test_repr(self):
          entry = self.create_file_entry()
          self.assertEqual(repr(entry), "<DirEntry 'file.txt'>")
  
      def test_fspath_protocol(self):
          entry = self.create_file_entry()
          self.assertEqual(os.fspath(entry), os.path.join(self.path, 'file.txt'))
  
      def test_fspath_protocol_bytes(self):
          bytes_filename = os.fsencode('bytesfile.txt')
          bytes_entry = self.create_file_entry(name=bytes_filename)
          fspath = os.fspath(bytes_entry)
          self.assertIsInstance(fspath, bytes)
          self.assertEqual(fspath,
                           os.path.join(os.fsencode(self.path),bytes_filename))
  
      def test_removed_dir(self):
          path = os.path.join(self.path, 'dir')
  
          os.mkdir(path)
          entry = self.get_entry('dir')
          os.rmdir(path)
  
          # On POSIX, is_dir() result depends if scandir() filled d_type or not
          if os.name == 'nt':
              self.assertTrue(entry.is_dir())
          self.assertFalse(entry.is_file())
          self.assertFalse(entry.is_symlink())
          if os.name == 'nt':
              self.assertRaises(FileNotFoundError, entry.inode)
              # don't fail
              entry.stat()
              entry.stat(follow_symlinks=False)
          else:
              self.assertGreater(entry.inode(), 0)
              self.assertRaises(FileNotFoundError, entry.stat)
              self.assertRaises(FileNotFoundError, entry.stat, follow_symlinks=False)
  
      def test_removed_file(self):
          entry = self.create_file_entry()
          os.unlink(entry.path)
  
          self.assertFalse(entry.is_dir())
          # On POSIX, is_dir() result depends if scandir() filled d_type or not
          if os.name == 'nt':
              self.assertTrue(entry.is_file())
          self.assertFalse(entry.is_symlink())
          if os.name == 'nt':
              self.assertRaises(FileNotFoundError, entry.inode)
              # don't fail
              entry.stat()
              entry.stat(follow_symlinks=False)
          else:
              self.assertGreater(entry.inode(), 0)
              self.assertRaises(FileNotFoundError, entry.stat)
              self.assertRaises(FileNotFoundError, entry.stat, follow_symlinks=False)
  
      def test_broken_symlink(self):
          if not support.can_symlink():
              return self.skipTest('cannot create symbolic link')
  
          filename = self.create_file("file.txt")
          os.symlink(filename,
                     os.path.join(self.path, "symlink.txt"))
          entries = self.get_entries(['file.txt', 'symlink.txt'])
          entry = entries['symlink.txt']
          os.unlink(filename)
  
          self.assertGreater(entry.inode(), 0)
          self.assertFalse(entry.is_dir())
          self.assertFalse(entry.is_file())  # broken symlink returns False
          self.assertFalse(entry.is_dir(follow_symlinks=False))
          self.assertFalse(entry.is_file(follow_symlinks=False))
          self.assertTrue(entry.is_symlink())
          self.assertRaises(FileNotFoundError, entry.stat)
          # don't fail
          entry.stat(follow_symlinks=False)
  
      def test_bytes(self):
          self.create_file("file.txt")
  
          path_bytes = os.fsencode(self.path)
          entries = list(os.scandir(path_bytes))
          self.assertEqual(len(entries), 1, entries)
          entry = entries[0]
  
          self.assertEqual(entry.name, b'file.txt')
          self.assertEqual(entry.path,
                           os.fsencode(os.path.join(self.path, 'file.txt')))
  
      def test_bytes_like(self):
          self.create_file("file.txt")
  
          for cls in bytearray, memoryview:
              path_bytes = cls(os.fsencode(self.path))
              with self.assertWarns(DeprecationWarning):
                  entries = list(os.scandir(path_bytes))
              self.assertEqual(len(entries), 1, entries)
              entry = entries[0]
  
              self.assertEqual(entry.name, b'file.txt')
              self.assertEqual(entry.path,
                               os.fsencode(os.path.join(self.path, 'file.txt')))
              self.assertIs(type(entry.name), bytes)
              self.assertIs(type(entry.path), bytes)
  
      @unittest.skipUnless(os.listdir in os.supports_fd,
                           'fd support for listdir required for this test.')
      def test_fd(self):
          self.assertIn(os.scandir, os.supports_fd)
          self.create_file('file.txt')
          expected_names = ['file.txt']
          if support.can_symlink():
              os.symlink('file.txt', os.path.join(self.path, 'link'))
              expected_names.append('link')
  
          fd = os.open(self.path, os.O_RDONLY)
          try:
              with os.scandir(fd) as it:
                  entries = list(it)
              names = [entry.name for entry in entries]
              self.assertEqual(sorted(names), expected_names)
              self.assertEqual(names, os.listdir(fd))
              for entry in entries:
                  self.assertEqual(entry.path, entry.name)
                  self.assertEqual(os.fspath(entry), entry.name)
                  self.assertEqual(entry.is_symlink(), entry.name == 'link')
                  if os.stat in os.supports_dir_fd:
                      st = os.stat(entry.name, dir_fd=fd)
                      self.assertEqual(entry.stat(), st)
                      st = os.stat(entry.name, dir_fd=fd, follow_symlinks=False)
                      self.assertEqual(entry.stat(follow_symlinks=False), st)
          finally:
              os.close(fd)
  
      def test_empty_path(self):
          self.assertRaises(FileNotFoundError, os.scandir, '')
  
      def test_consume_iterator_twice(self):
          self.create_file("file.txt")
          iterator = os.scandir(self.path)
  
          entries = list(iterator)
          self.assertEqual(len(entries), 1, entries)
  
          # check than consuming the iterator twice doesn't raise exception
          entries2 = list(iterator)
          self.assertEqual(len(entries2), 0, entries2)
  
      def test_bad_path_type(self):
          for obj in [1.234, {}, []]:
              self.assertRaises(TypeError, os.scandir, obj)
  
      def test_close(self):
          self.create_file("file.txt")
          self.create_file("file2.txt")
          iterator = os.scandir(self.path)
          next(iterator)
          iterator.close()
          # multiple closes
          iterator.close()
          with self.check_no_resource_warning():
              del iterator
  
      def test_context_manager(self):
          self.create_file("file.txt")
          self.create_file("file2.txt")
          with os.scandir(self.path) as iterator:
              next(iterator)
          with self.check_no_resource_warning():
              del iterator
  
      def test_context_manager_close(self):
          self.create_file("file.txt")
          self.create_file("file2.txt")
          with os.scandir(self.path) as iterator:
              next(iterator)
              iterator.close()
  
      def test_context_manager_exception(self):
          self.create_file("file.txt")
          self.create_file("file2.txt")
          with self.assertRaises(ZeroDivisionError):
              with os.scandir(self.path) as iterator:
                  next(iterator)
                  1/0
          with self.check_no_resource_warning():
              del iterator
  
      def test_resource_warning(self):
          self.create_file("file.txt")
          self.create_file("file2.txt")
          iterator = os.scandir(self.path)
          next(iterator)
          with self.assertWarns(ResourceWarning):
              del iterator
              support.gc_collect()
          # exhausted iterator
          iterator = os.scandir(self.path)
          list(iterator)
          with self.check_no_resource_warning():
              del iterator
  
  
  class TestPEP519(unittest.TestCase):
  
      # Abstracted so it can be overridden to test pure Python implementation
      # if a C version is provided.
      fspath = staticmethod(os.fspath)
  
      def test_return_bytes(self):
          for b in b'hello', b'goodbye', b'some/path/and/file':
              self.assertEqual(b, self.fspath(b))
  
      def test_return_string(self):
          for s in 'hello', 'goodbye', 'some/path/and/file':
              self.assertEqual(s, self.fspath(s))
  
      def test_fsencode_fsdecode(self):
          for p in "path/like/object", b"path/like/object":
              pathlike = FakePath(p)
  
              self.assertEqual(p, self.fspath(pathlike))
              self.assertEqual(b"path/like/object", os.fsencode(pathlike))
              self.assertEqual("path/like/object", os.fsdecode(pathlike))
  
      def test_pathlike(self):
          self.assertEqual('#feelthegil', self.fspath(FakePath('#feelthegil')))
          self.assertTrue(issubclass(FakePath, os.PathLike))
          self.assertTrue(isinstance(FakePath('x'), os.PathLike))
  
      def test_garbage_in_exception_out(self):
          vapor = type('blah', (), {})
          for o in int, type, os, vapor():
              self.assertRaises(TypeError, self.fspath, o)
  
      def test_argument_required(self):
          self.assertRaises(TypeError, self.fspath)
  
      def test_bad_pathlike(self):
          # __fspath__ returns a value other than str or bytes.
          self.assertRaises(TypeError, self.fspath, FakePath(42))
          # __fspath__ attribute that is not callable.
          c = type('foo', (), {})
          c.__fspath__ = 1
          self.assertRaises(TypeError, self.fspath, c())
          # __fspath__ raises an exception.
          self.assertRaises(ZeroDivisionError, self.fspath,
                            FakePath(ZeroDivisionError()))
  
  
  class TimesTests(unittest.TestCase):
      def test_times(self):
          times = os.times()
          self.assertIsInstance(times, os.times_result)
  
          for field in ('user', 'system', 'children_user', 'children_system',
                        'elapsed'):
              value = getattr(times, field)
              self.assertIsInstance(value, float)
  
          if os.name == 'nt':
              self.assertEqual(times.children_user, 0)
              self.assertEqual(times.children_system, 0)
              self.assertEqual(times.elapsed, 0)
  
  
  # Only test if the C version is provided, otherwise TestPEP519 already tested
  # the pure Python implementation.
  if hasattr(os, "_fspath"):
      class TestPEP519PurePython(TestPEP519):
  
          """Explicitly test the pure Python implementation of os.fspath()."""
  
          fspath = staticmethod(os._fspath)
  
  
  if __name__ == "__main__":
      unittest.main()
  