"""Parse a Python module and describe its classes and methods. Parse enough of a Python file to recognize imports and class and method definitions, and to find out the superclasses of a class. The interface consists of a single function: readmodule_ex(module [, path]) where module is the name of a Python module, and path is an optional list of directories where the module is to be searched. If present, path is prepended to the system search path sys.path. The return value is a dictionary. The keys of the dictionary are the names of the classes defined in the module (including classes that are defined via the from XXX import YYY construct). The values are class instances of the class Class defined here. One special key/value pair is present for packages: the key '__path__' has a list as its value which contains the package search path. A class is described by the class Class in this module. Instances of this class have the following instance variables: module -- the module name name -- the name of the class super -- a list of super classes (Class instances) methods -- a dictionary of methods file -- the file in which the class was defined lineno -- the line in the file on which the class statement occurred The dictionary of methods uses the method names as keys and the line numbers on which the method was defined as values. If the name of a super class is not recognized, the corresponding entry in the list of super classes is not a class instance but a string giving the name of the super class. Since import statements are recognized and imported modules are scanned as well, this shouldn't happen often. A function is described by the class Function in this module. Instances of this class have the following instance variables: module -- the module name name -- the name of the class file -- the file in which the class was defined lineno -- the line in the file on which the class statement occurred """ import io import os import sys import importlib import tokenize from token import NAME, DEDENT, OP from operator import itemgetter __all__ = ["readmodule", "readmodule_ex", "Class", "Function"] _modules = {} # cache of modules we've seen # each Python class is represented by an instance of this class class Class: '''Class to represent a Python class.''' def __init__(self, module, name, super, file, lineno): self.module = module self.name = name if super is None: super = [] self.super = super self.methods = {} self.file = file self.lineno = lineno def _addmethod(self, name, lineno): self.methods[name] = lineno class Function: '''Class to represent a top-level Python function''' def __init__(self, module, name, file, lineno): self.module = module self.name = name self.file = file self.lineno = lineno def readmodule(module, path=None): '''Backwards compatible interface. Call readmodule_ex() and then only keep Class objects from the resulting dictionary.''' res = {} for key, value in _readmodule(module, path or []).items(): if isinstance(value, Class): res[key] = value return res def readmodule_ex(module, path=None): '''Read a module file and return a dictionary of classes. Search for MODULE in PATH and sys.path, read and parse the module and return a dictionary with one entry for each class found in the module. ''' return _readmodule(module, path or []) def _readmodule(module, path, inpackage=None): '''Do the hard work for readmodule[_ex]. If INPACKAGE is given, it must be the dotted name of the package in which we are searching for a submodule, and then PATH must be the package search path; otherwise, we are searching for a top-level module, and PATH is combined with sys.path. ''' # Compute the full module name (prepending inpackage if set) if inpackage is not None: fullmodule = "%s.%s" % (inpackage, module) else: fullmodule = module # Check in the cache if fullmodule in _modules: return _modules[fullmodule] # Initialize the dict for this module's contents dict = {} # Check if it is a built-in module; we don't do much for these if module in sys.builtin_module_names and inpackage is None: _modules[module] = dict return dict # Check for a dotted module name i = module.rfind('.') if i >= 0: package = module[:i] submodule = module[i+1:] parent = _readmodule(package, path, inpackage) if inpackage is not None: package = "%s.%s" % (inpackage, package) if not '__path__' in parent: raise ImportError('No package named {}'.format(package)) return _readmodule(submodule, parent['__path__'], package) # Search the path for the module f = None if inpackage is not None: search_path = path else: search_path = path + sys.path loader = importlib.find_loader(fullmodule, search_path) fname = loader.get_filename(fullmodule) _modules[fullmodule] = dict if loader.is_package(fullmodule): dict['__path__'] = [os.path.dirname(fname)] try: source = loader.get_source(fullmodule) if source is None: return dict except (AttributeError, ImportError): # not Python source, can't do anything with this module return dict f = io.StringIO(source) stack = [] # stack of (class, indent) pairs g = tokenize.generate_tokens(f.readline) try: for tokentype, token, start, _end, _line in g: if tokentype == DEDENT: lineno, thisindent = start # close nested classes and defs while stack and stack[-1][1] >= thisindent: del stack[-1] elif token == 'def': lineno, thisindent = start # close previous nested classes and defs while stack and stack[-1][1] >= thisindent: del stack[-1] tokentype, meth_name, start = next(g)[0:3] if tokentype != NAME: continue # Syntax error if stack: cur_class = stack[-1][0] if isinstance(cur_class, Class): # it's a method cur_class._addmethod(meth_name, lineno) # else it's a nested def else: # it's a function dict[meth_name] = Function(fullmodule, meth_name, fname, lineno) stack.append((None, thisindent)) # Marker for nested fns elif token == 'class': lineno, thisindent = start # close previous nested classes and defs while stack and stack[-1][1] >= thisindent: del stack[-1] tokentype, class_name, start = next(g)[0:3] if tokentype != NAME: continue # Syntax error # parse what follows the class name tokentype, token, start = next(g)[0:3] inherit = None if token == '(': names = [] # List of superclasses # there's a list of superclasses level = 1 super = [] # Tokens making up current superclass while True: tokentype, token, start = next(g)[0:3] if token in (')', ',') and level == 1: n = "".join(super) if n in dict: # we know this super class n = dict[n] else: c = n.split('.') if len(c) > 1: # super class is of the form # module.class: look in module for # class m = c[-2] c = c[-1] if m in _modules: d = _modules[m] if c in d: n = d[c] names.append(n) super = [] if token == '(': level += 1 elif token == ')': level -= 1 if level == 0: break elif token == ',' and level == 1: pass # only use NAME and OP (== dot) tokens for type name elif tokentype in (NAME, OP) and level == 1: super.append(token) # expressions in the base list are not supported inherit = names cur_class = Class(fullmodule, class_name, inherit, fname, lineno) if not stack: dict[class_name] = cur_class stack.append((cur_class, thisindent)) elif token == 'import' and start[1] == 0: modules = _getnamelist(g) for mod, _mod2 in modules: try: # Recursively read the imported module if inpackage is None: _readmodule(mod, path) else: try: _readmodule(mod, path, inpackage) except ImportError: _readmodule(mod, []) except: # If we can't find or parse the imported module, # too bad -- don't die here. pass elif token == 'from' and start[1] == 0: mod, token = _getname(g) if not mod or token != "import": continue names = _getnamelist(g) try: # Recursively read the imported module d = _readmodule(mod, path, inpackage) except: # If we can't find or parse the imported module, # too bad -- don't die here. continue # add any classes that were defined in the imported module # to our name space if they were mentioned in the list for n, n2 in names: if n in d: dict[n2 or n] = d[n] elif n == '*': # don't add names that start with _ for n in d: if n[0] != '_': dict[n] = d[n] except StopIteration: pass f.close() return dict def _getnamelist(g): # Helper to get a comma-separated list of dotted names plus 'as' # clauses. Return a list of pairs (name, name2) where name2 is # the 'as' name, or None if there is no 'as' clause. names = [] while True: name, token = _getname(g) if not name: break if token == 'as': name2, token = _getname(g) else: name2 = None names.append((name, name2)) while token != "," and "\n" not in token: token = next(g)[1] if token != ",": break return names def _getname(g): # Helper to get a dotted name, return a pair (name, token) where # name is the dotted name, or None if there was no dotted name, # and token is the next input token. parts = [] tokentype, token = next(g)[0:2] if tokentype != NAME and token != '*': return (None, token) parts.append(token) while True: tokentype, token = next(g)[0:2] if token != '.': break tokentype, token = next(g)[0:2] if tokentype != NAME: break parts.append(token) return (".".join(parts), token) def _main(): # Main program for testing. import os mod = sys.argv[1] if os.path.exists(mod): path = [os.path.dirname(mod)] mod = os.path.basename(mod) if mod.lower().endswith(".py"): mod = mod[:-3] else: path = [] dict = readmodule_ex(mod, path) objs = list(dict.values()) objs.sort(key=lambda a: getattr(a, 'lineno', 0)) for obj in objs: if isinstance(obj, Class): print("class", obj.name, obj.super, obj.lineno) methods = sorted(obj.methods.items(), key=itemgetter(1)) for name, lineno in methods: if name != "__path__": print(" def", name, lineno) elif isinstance(obj, Function): print("def", obj.name, obj.lineno) if __name__ == "__main__": _main() #n302'>302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 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# 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 os
import errno
import unittest
import warnings
import sys
import signal
import subprocess
import time
import shutil
from test import support
import contextlib
import mmap
import uuid
import stat
from test.script_helper import assert_python_ok

# 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(os, "confstr_names") and
    "CS_GNU_LIBPTHREAD_VERSION" in os.confstr_names):
    libpthread = os.confstr("CS_GNU_LIBPTHREAD_VERSION")
    USING_LINUXTHREADS= libpthread.startswith("linuxthreads")
else:
    USING_LINUXTHREADS= False

# Tests creating TESTFN
class FileTests(unittest.TestCase):
    def setUp(self):
        if os.path.exists(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")

    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)


# Test attributes on return values from os.*stat* family.
class StatAttributeTests(unittest.TestCase):
    def setUp(self):
        os.mkdir(support.TESTFN)
        self.fname = os.path.join(support.TESTFN, "f1")
        f = open(self.fname, 'wb')
        f.write(b"ABC")
        f.close()

    def tearDown(self):
        os.unlink(self.fname)
        os.rmdir(support.TESTFN)

    def check_stat_attributes(self, fname):
        if not hasattr(os, "stat"):
            return

        import stat
        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)

        try:
            result[200]
            self.fail("No exception thrown")
        except IndexError:
            pass

        # Make sure that assignment fails
        try:
            result.st_mode = 1
            self.fail("No exception thrown")
        except AttributeError:
            pass

        try:
            result.st_rdev = 1
            self.fail("No exception thrown")
        except (AttributeError, TypeError):
            pass

        try:
            result.parrot = 1
            self.fail("No exception thrown")
        except AttributeError:
            pass

        # Use the stat_result constructor with a too-short tuple.
        try:
            result2 = os.stat_result((10,))
            self.fail("No exception thrown")
        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_statvfs_attributes(self):
        if not hasattr(os, "statvfs"):
            return

        try:
            result = os.statvfs(self.fname)
        except OSError as e:
            # On AtheOS, glibc always returns ENOSYS
            if e.errno == errno.ENOSYS:
                return

        # 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])

        # Make sure that assignment really fails
        try:
            result.f_bfree = 1
            self.fail("No exception thrown")
        except AttributeError:
            pass

        try:
            result.parrot = 1
            self.fail("No exception thrown")
        except AttributeError:
            pass

        # Use the constructor with a too-short tuple.
        try:
            result2 = os.statvfs_result((10,))
            self.fail("No exception thrown")
        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

    def test_utime_dir(self):
        delta = 1000000
        st = os.stat(support.TESTFN)
        # round to int, because some systems may support sub-second
        # time stamps in stat, but not in utime.
        os.utime(support.TESTFN, (st.st_atime, int(st.st_mtime-delta)))
        st2 = os.stat(support.TESTFN)
        self.assertEqual(st2.st_mtime, int(st.st_mtime-delta))

    # Restrict test to Win32, since there is no guarantee other
    # systems support centiseconds
    if sys.platform == 'win32':
        def get_file_system(path):
            root = os.path.splitdrive(os.path.abspath(path))[0] + '\\'
            import ctypes
            kernel32 = ctypes.windll.kernel32
            buf = ctypes.create_unicode_buffer("", 100)
            if kernel32.GetVolumeInformationW(root, None, 0, None, None, None, buf, len(buf)):
                return buf.value

        if get_file_system(support.TESTFN) == "NTFS":
            def test_1565150(self):
                t1 = 1159195039.25
                os.utime(self.fname, (t1, t1))
                self.assertEqual(os.stat(self.fname).st_mtime, t1)

            def test_large_time(self):
                t1 = 5000000000 # some day in 2128
                os.utime(self.fname, (t1, t1))
                self.assertEqual(os.stat(self.fname).st_mtime, t1)

        def test_1686475(self):
            # Verify that an open file can be stat'ed
            try:
                os.stat(r"c:\pagefile.sys")
            except WindowsError as e:
                if e.errno == 2: # file does not exist; cannot run test
                    return
                self.fail("Could not stat pagefile.sys")

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
    def test_update2(self):
        os.environ.clear()
        if os.path.exists("/bin/sh"):
            os.environ.update(HELLO="World")
            with os.popen("/bin/sh -c 'echo $HELLO'") as popen:
                value = popen.read().strip()
                self.assertEqual(value, "World")

    def test_os_popen_iter(self):
        if os.path.exists("/bin/sh"):
            with os.popen(
                "/bin/sh -c 'echo \"line1\nline2\nline3\"'") 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 FreeBSD < 7 and OS X < 10.6, unsetenv() doesn't return a value (issue
    # #13415).
    @unittest.skipIf(sys.platform.startswith(('freebsd', 'darwin')),
                     "due to known OS bug: see issue #13415")
    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)

class WalkTests(unittest.TestCase):
    """Tests for os.walk()."""

    def test_traversal(self):
        import os
        from os.path import join

        # 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
        #           link/           a symlink to TESTFN.2
        #       TEST2/
        #         tmp4              a lone file
        walk_path = join(support.TESTFN, "TEST1")
        sub1_path = join(walk_path, "SUB1")
        sub11_path = join(sub1_path, "SUB11")
        sub2_path = join(walk_path, "SUB2")
        tmp1_path = join(walk_path, "tmp1")
        tmp2_path = join(sub1_path, "tmp2")
        tmp3_path = join(sub2_path, "tmp3")
        link_path = join(sub2_path, "link")
        t2_path = join(support.TESTFN, "TEST2")
        tmp4_path = join(support.TESTFN, "TEST2", "tmp4")

        # Create stuff.
        os.makedirs(sub11_path)
        os.makedirs(sub2_path)
        os.makedirs(t2_path)
        for path in tmp1_path, tmp2_path, tmp3_path, tmp4_path:
            f = open(path, "w")
            f.write("I'm " + path + " and proud of it.  Blame test_os.\n")
            f.close()
        if support.can_symlink():
            if os.name == 'nt':
                def symlink_to_dir(src, dest):
                    os.symlink(src, dest, True)
            else:
                symlink_to_dir = os.symlink
            symlink_to_dir(os.path.abspath(t2_path), link_path)
            sub2_tree = (sub2_path, ["link"], ["tmp3"])
        else:
            sub2_tree = (sub2_path, [], ["tmp3"])

        # Walk top-down.
        all = list(os.walk(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()
        self.assertEqual(all[0], (walk_path, ["SUB1", "SUB2"], ["tmp1"]))
        self.assertEqual(all[1 + flipped], (sub1_path, ["SUB11"], ["tmp2"]))
        self.assertEqual(all[2 + flipped], (sub11_path, [], []))
        self.assertEqual(all[3 - 2 * flipped], sub2_tree)

        # Prune the search.
        all = []
        for root, dirs, files in os.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], (walk_path, ["SUB2"], ["tmp1"]))
        self.assertEqual(all[1], sub2_tree)

        # Walk bottom-up.
        all = list(os.walk(walk_path, topdown=False))
        self.assertEqual(len(all), 4)
        # 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()
        self.assertEqual(all[3], (walk_path, ["SUB1", "SUB2"], ["tmp1"]))
        self.assertEqual(all[flipped], (sub11_path, [], []))
        self.assertEqual(all[flipped + 1], (sub1_path, ["SUB11"], ["tmp2"]))
        self.assertEqual(all[2 - 2 * flipped], sub2_tree)

        if support.can_symlink():
            # Walk, following symlinks.
            for root, dirs, files in os.walk(walk_path, followlinks=True):
                if root == link_path:
                    self.assertEqual(dirs, [])
                    self.assertEqual(files, ["tmp4"])
                    break
            else:
                self.fail("Didn't follow symlink with followlinks=True")

    def tearDown(self):
        # Tear everything down.  This is a decent use for bottom-up on
        # Windows, which doesn't have a recursive delete command.  The
        # (not so) subtlety is that rmdir will fail unless the dir's
        # kids are removed first, so bottom up is essential.
        for root, dirs, files in os.walk(support.TESTFN, topdown=False):
            for name in files:
                os.remove(os.path.join(root, name))
            for name in dirs:
                dirname = os.path.join(root, name)
                if not os.path.islink(dirname):
                    os.rmdir(dirname)
                else:
                    os.remove(dirname)
        os.rmdir(support.TESTFN)

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_exist_ok_existing_directory(self):
        path = os.path.join(support.TESTFN, 'dir1')
        mode = 0o777
        old_mask = os.umask(0o022)
        try:
            os.makedirs(path, mode)
            self.assertRaises(OSError, os.makedirs, path, mode)
            self.assertRaises(OSError, os.makedirs, path, mode, exist_ok=False)
            self.assertRaises(OSError, os.makedirs, path, 0o776, exist_ok=True)
            os.makedirs(path, mode=mode, exist_ok=True)
        finally:
            os.umask(old_mask)

    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)
            os.chmod(support.TESTFN, existing_testfn_mode | S_ISGID)
            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)
            with self.assertRaises(OSError):
                # Should fail 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')
        f = open(path, 'w')
        f.write('abc')
        f.close()
        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)

class DevNullTests(unittest.TestCase):
    def test_devnull(self):
        with open(os.devnull, 'wb') 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)
        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), 16)
        return stdout

    def test_urandom_subprocess(self):
        data1 = self.get_urandom_subprocess(16)
        data2 = self.get_urandom_subprocess(16)
        self.assertNotEqual(data1, data2)

@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

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_execvpe_with_bad_arglist(self):
        self.assertRaises(ValueError, os.execvpe, 'notepad', [], None)

    @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)


class Win32ErrorTests(unittest.TestCase):
    def test_rename(self):
        self.assertRaises(WindowsError, os.rename, support.TESTFN, support.TESTFN+".bak")

    def test_remove(self):
        self.assertRaises(WindowsError, os.remove, support.TESTFN)

    def test_chdir(self):
        self.assertRaises(WindowsError, os.chdir, support.TESTFN)

    def test_mkdir(self):
        f = open(support.TESTFN, "w")
        try:
            self.assertRaises(WindowsError, os.mkdir, support.TESTFN)
        finally:
            f.close()
            os.unlink(support.TESTFN)

    def test_utime(self):
        self.assertRaises(WindowsError, os.utime, support.TESTFN, None)

    def test_chmod(self):
        self.assertRaises(WindowsError, 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'r 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 a OSError with a bad file descriptor"
                      % f)

    def test_isatty(self):
        if hasattr(os, "isatty"):
            self.assertEqual(os.isatty(support.make_bad_fd()), False)

    def test_closerange(self):
        if hasattr(os, "closerange"):
            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)

    def test_dup2(self):
        if hasattr(os, "dup2"):
            self.check(os.dup2, 20)

    def test_fchmod(self):
        if hasattr(os, "fchmod"):
            self.check(os.fchmod, 0)

    def test_fchown(self):
        if hasattr(os, "fchown"):
            self.check(os.fchown, -1, -1)

    def test_fpathconf(self):
        if hasattr(os, "fpathconf"):
            self.check(os.fpathconf, "PC_NAME_MAX")

    def test_ftruncate(self):
        if hasattr(os, "ftruncate"):
            self.check(os.ftruncate, 0)

    def test_lseek(self):
        if hasattr(os, "lseek"):
            self.check(os.lseek, 0, 0)

    def test_read(self):
        if hasattr(os, "read"):
            self.check(os.read, 1)

    def test_tcsetpgrpt(self):
        if hasattr(os, "tcsetpgrp"):
            self.check(os.tcsetpgrp, 0)

    def test_write(self):
        if hasattr(os, "write"):
            self.check(os.write, b" ")


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):
        with open(file1, "w") as f1:
            f1.write("test")

        os.link(file1, file2)
        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)

if sys.platform != 'win32':
    class Win32ErrorTests(unittest.TestCase):
        pass

    class PosixUidGidTests(unittest.TestCase):
        if hasattr(os, 'setuid'):
            def test_setuid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setuid, 0)
                self.assertRaises(OverflowError, os.setuid, 1<<32)

        if hasattr(os, 'setgid'):
            def test_setgid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setgid, 0)
                self.assertRaises(OverflowError, os.setgid, 1<<32)

        if hasattr(os, 'seteuid'):
            def test_seteuid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.seteuid, 0)
                self.assertRaises(OverflowError, os.seteuid, 1<<32)

        if hasattr(os, 'setegid'):
            def test_setegid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setegid, 0)
                self.assertRaises(OverflowError, os.setegid, 1<<32)

        if hasattr(os, 'setreuid'):
            def test_setreuid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setreuid, 0, 0)
                self.assertRaises(OverflowError, os.setreuid, 1<<32, 0)
                self.assertRaises(OverflowError, os.setreuid, 0, 1<<32)

            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)'])

        if hasattr(os, 'setregid'):
            def test_setregid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setregid, 0, 0)
                self.assertRaises(OverflowError, os.setregid, 1<<32, 0)
                self.assertRaises(OverflowError, os.setregid, 0, 1<<32)

            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)'])

    class Pep383Tests(unittest.TestCase):
        def setUp(self):
            if support.TESTFN_UNENCODABLE:
                self.dir = support.TESTFN_UNENCODABLE
            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 not bytesfn:
                self.skipTest("couldn't create any non-ascii filename")

            self.unicodefn = set()
            os.mkdir(self.dir)
            try:
                for fn in bytesfn:
                    f = open(os.path.join(self.bdir, fn), "w")
                    f.close()
                    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)

        def test_open(self):
            for fn in self.unicodefn:
                f = open(os.path.join(self.dir, fn), 'rb')
                f.close()

        def test_stat(self):
            for fn in self.unicodefn:
                os.stat(os.path.join(self.dir, fn))
else:
    class PosixUidGidTests(unittest.TestCase):
        pass
    class Pep383Tests(unittest.TestCase):
        pass

@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")
@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, True)
        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)

    @unittest.skip("currently fails; consider for improvement")
    def test_isdir_on_directory_link_to_missing_target(self):
        self._create_missing_dir_link()
        # consider having isdir return true for directory links
        self.assertTrue(os.path.isdir(self.missing_link))

    @unittest.skip("currently fails; consider for improvement")
    def test_rmdir_on_directory_link_to_missing_target(self):
        self._create_missing_dir_link()
        # consider allowing rmdir to remove directory links
        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")
        try:
            os.mkdir(level1)
            os.mkdir(level2)
            os.mkdir(level3)

            file1 = os.path.abspath(os.path.join(level1, "file1"))

            with open(file1, "w") as f:
                f.write("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)
        except OSError as err:
            self.fail(err)
        finally:
            os.remove(file1)
            shutil.rmtree(level1)


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 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())


# 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)


def test_main():
    support.run_unittest(
        FileTests,
        StatAttributeTests,
        EnvironTests,
        WalkTests,
        MakedirTests,
        DevNullTests,
        URandomTests,
        ExecTests,
        Win32ErrorTests,
        TestInvalidFD,
        PosixUidGidTests,
        Pep383Tests,
        Win32KillTests,
        Win32SymlinkTests,
        FSEncodingTests,
        PidTests,
        LoginTests,
        LinkTests,
    )

if __name__ == "__main__":
    test_main()