Backport PR #6581: Properly mock winreg functions for test

Fixes a lot of test failures on Python 3.4 on Windows, caused by importlib trying to use our mocked out winreg functions when reload(path) was called.

IPython/utils/tests/test_path.py

@@ -1,677 +1,669 b''
 # encoding: utf-8
 """Tests for IPython.utils.path.py"""
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import with_statement
 
 import errno
 import os
 import shutil
 import sys
 import tempfile
 import warnings
 from contextlib import contextmanager
 
+try:  # Python 3.3+
+    from unittest.mock import patch
+except ImportError:
+    from mock import patch
+
 from os.path import join, abspath, split
 
 import nose.tools as nt
 
 from nose import with_setup
 
 import IPython
 from IPython.testing import decorators as dec
 from IPython.testing.decorators import (skip_if_not_win32, skip_win32,
                                         onlyif_unicode_paths,)
 from IPython.testing.tools import make_tempfile, AssertPrints
 from IPython.utils import path
 from IPython.utils import py3compat
 from IPython.utils.tempdir import TemporaryDirectory
 
 # Platform-dependent imports
 try:
     import winreg as wreg  # Py 3
 except ImportError:
     try:
         import _winreg as wreg  # Py 2
     except ImportError:
         #Fake _winreg module on none windows platforms
         import types
         wr_name = "winreg" if py3compat.PY3 else "_winreg"
         sys.modules[wr_name] = types.ModuleType(wr_name)
         try:
             import winreg as wreg
         except ImportError:
             import _winreg as wreg
         #Add entries that needs to be stubbed by the testing code
         (wreg.OpenKey, wreg.QueryValueEx,) = (None, None)
 
 try:
     reload
 except NameError:   # Python 3
     from imp import reload
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 env = os.environ
 TEST_FILE_PATH = split(abspath(__file__))[0]
 TMP_TEST_DIR = tempfile.mkdtemp()
 HOME_TEST_DIR = join(TMP_TEST_DIR, "home_test_dir")
 XDG_TEST_DIR = join(HOME_TEST_DIR, "xdg_test_dir")
 XDG_CACHE_DIR = join(HOME_TEST_DIR, "xdg_cache_dir")
 IP_TEST_DIR = join(HOME_TEST_DIR,'.ipython')
 #
 # Setup/teardown functions/decorators
 #
 
 def setup():
     """Setup testenvironment for the module:
 
             - Adds dummy home dir tree
     """
     # Do not mask exceptions here.  In particular, catching WindowsError is a
     # problem because that exception is only defined on Windows...
     os.makedirs(IP_TEST_DIR)
     os.makedirs(os.path.join(XDG_TEST_DIR, 'ipython'))
     os.makedirs(os.path.join(XDG_CACHE_DIR, 'ipython'))
 
 
 def teardown():
     """Teardown testenvironment for the module:
 
             - Remove dummy home dir tree
     """
     # Note: we remove the parent test dir, which is the root of all test
     # subdirs we may have created.  Use shutil instead of os.removedirs, so
     # that non-empty directories are all recursively removed.
     shutil.rmtree(TMP_TEST_DIR)
 
 
 def setup_environment():
     """Setup testenvironment for some functions that are tested
     in this module. In particular this functions stores attributes
     and other things that we need to stub in some test functions.
     This needs to be done on a function level and not module level because
     each testfunction needs a pristine environment.
     """
     global oldstuff, platformstuff
     oldstuff = (env.copy(), os.name, sys.platform, path.get_home_dir, IPython.__file__, os.getcwd())
 
-    if os.name == 'nt':
-        platformstuff = (wreg.OpenKey, wreg.QueryValueEx,)
-
-
 def teardown_environment():
     """Restore things that were remembered by the setup_environment function
     """
     (oldenv, os.name, sys.platform, path.get_home_dir, IPython.__file__, old_wd) = oldstuff
     os.chdir(old_wd)
     reload(path)
 
     for key in list(env):
         if key not in oldenv:
             del env[key]
     env.update(oldenv)
     if hasattr(sys, 'frozen'):
         del sys.frozen
-    if os.name == 'nt':
-        (wreg.OpenKey, wreg.QueryValueEx,) = platformstuff
 
 # Build decorator that uses the setup_environment/setup_environment
 with_environment = with_setup(setup_environment, teardown_environment)
 
 @contextmanager
 def patch_get_home_dir(dirpath):
     orig_get_home_dir = path.get_home_dir
     path.get_home_dir = lambda : dirpath
     try:
         yield
     finally:
         path.get_home_dir = orig_get_home_dir
 
 @skip_if_not_win32
 @with_environment
 def test_get_home_dir_1():
     """Testcase for py2exe logic, un-compressed lib
     """
     unfrozen = path.get_home_dir()
     sys.frozen = True
 
     #fake filename for IPython.__init__
     IPython.__file__ = abspath(join(HOME_TEST_DIR, "Lib/IPython/__init__.py"))
 
     home_dir = path.get_home_dir()
     nt.assert_equal(home_dir, unfrozen)
 
 
 @skip_if_not_win32
 @with_environment
 def test_get_home_dir_2():
     """Testcase for py2exe logic, compressed lib
     """
     unfrozen = path.get_home_dir()
     sys.frozen = True
     #fake filename for IPython.__init__
     IPython.__file__ = abspath(join(HOME_TEST_DIR, "Library.zip/IPython/__init__.py")).lower()
 
     home_dir = path.get_home_dir(True)
     nt.assert_equal(home_dir, unfrozen)
 
 
 @with_environment
 def test_get_home_dir_3():
     """get_home_dir() uses $HOME if set"""
     env["HOME"] = HOME_TEST_DIR
     home_dir = path.get_home_dir(True)
     # get_home_dir expands symlinks
     nt.assert_equal(home_dir, os.path.realpath(env["HOME"]))
 
 
 @with_environment
 def test_get_home_dir_4():
     """get_home_dir() still works if $HOME is not set"""
 
     if 'HOME' in env: del env['HOME']
     # this should still succeed, but we don't care what the answer is
     home = path.get_home_dir(False)
 
 @with_environment
 def test_get_home_dir_5():
     """raise HomeDirError if $HOME is specified, but not a writable dir"""
     env['HOME'] = abspath(HOME_TEST_DIR+'garbage')
     # set os.name = posix, to prevent My Documents fallback on Windows
     os.name = 'posix'
     nt.assert_raises(path.HomeDirError, path.get_home_dir, True)
 
-
 # Should we stub wreg fully so we can run the test on all platforms?
 @skip_if_not_win32
 @with_environment
 def test_get_home_dir_8():
     """Using registry hack for 'My Documents', os=='nt'
 
     HOMESHARE, HOMEDRIVE, HOMEPATH, USERPROFILE and others are missing.
     """
     os.name = 'nt'
     # Remove from stub environment all keys that may be set
     for key in ['HOME', 'HOMESHARE', 'HOMEDRIVE', 'HOMEPATH', 'USERPROFILE']:
         env.pop(key, None)
 
-    #Stub windows registry functions
-    def OpenKey(x, y):
-        class key:
-            def Close(self):
-                pass
-        return key()
-    def QueryValueEx(x, y):
-        return [abspath(HOME_TEST_DIR)]
-
-    wreg.OpenKey = OpenKey
-    wreg.QueryValueEx = QueryValueEx
+    class key:
+        def Close(self):
+            pass
 
-    home_dir = path.get_home_dir()
+    with patch.object(wreg, 'OpenKey', return_value=key()), \
+         patch.object(wreg, 'QueryValueEx', return_value=[abspath(HOME_TEST_DIR)]):
+        home_dir = path.get_home_dir()
     nt.assert_equal(home_dir, abspath(HOME_TEST_DIR))
 
 
 @with_environment
 def test_get_ipython_dir_1():
     """test_get_ipython_dir_1, Testcase to see if we can call get_ipython_dir without Exceptions."""
     env_ipdir = os.path.join("someplace", ".ipython")
     path._writable_dir = lambda path: True
     env['IPYTHONDIR'] = env_ipdir
     ipdir = path.get_ipython_dir()
     nt.assert_equal(ipdir, env_ipdir)
 
 
 @with_environment
 def test_get_ipython_dir_2():
     """test_get_ipython_dir_2, Testcase to see if we can call get_ipython_dir without Exceptions."""
     with patch_get_home_dir('someplace'):
         path.get_xdg_dir = lambda : None
         path._writable_dir = lambda path: True
         os.name = "posix"
         env.pop('IPYTHON_DIR', None)
         env.pop('IPYTHONDIR', None)
         env.pop('XDG_CONFIG_HOME', None)
         ipdir = path.get_ipython_dir()
         nt.assert_equal(ipdir, os.path.join("someplace", ".ipython"))
 
 @with_environment
 def test_get_ipython_dir_3():
     """test_get_ipython_dir_3, move XDG if defined, and .ipython doesn't exist."""
     tmphome = TemporaryDirectory()
     try:
         with patch_get_home_dir(tmphome.name):
             os.name = "posix"
             env.pop('IPYTHON_DIR', None)
             env.pop('IPYTHONDIR', None)
             env['XDG_CONFIG_HOME'] = XDG_TEST_DIR
 
             with warnings.catch_warnings(record=True) as w:
                 ipdir = path.get_ipython_dir()
 
             nt.assert_equal(ipdir, os.path.join(tmphome.name, ".ipython"))
             if sys.platform != 'darwin':
                 nt.assert_equal(len(w), 1)
                 nt.assert_in('Moving', str(w[0]))
     finally:
         tmphome.cleanup()
 
 @with_environment
 def test_get_ipython_dir_4():
     """test_get_ipython_dir_4, warn if XDG and home both exist."""
     with patch_get_home_dir(HOME_TEST_DIR):
         os.name = "posix"
         env.pop('IPYTHON_DIR', None)
         env.pop('IPYTHONDIR', None)
         env['XDG_CONFIG_HOME'] = XDG_TEST_DIR
         try:
             os.mkdir(os.path.join(XDG_TEST_DIR, 'ipython'))
         except OSError as e:
             if e.errno != errno.EEXIST:
                 raise
 
         with warnings.catch_warnings(record=True) as w:
             ipdir = path.get_ipython_dir()
 
         nt.assert_equal(ipdir, os.path.join(HOME_TEST_DIR, ".ipython"))
         if sys.platform != 'darwin':
             nt.assert_equal(len(w), 1)
             nt.assert_in('Ignoring', str(w[0]))
 
 @with_environment
 def test_get_ipython_dir_5():
     """test_get_ipython_dir_5, use .ipython if exists and XDG defined, but doesn't exist."""
     with patch_get_home_dir(HOME_TEST_DIR):
         os.name = "posix"
         env.pop('IPYTHON_DIR', None)
         env.pop('IPYTHONDIR', None)
         env['XDG_CONFIG_HOME'] = XDG_TEST_DIR
         try:
             os.rmdir(os.path.join(XDG_TEST_DIR, 'ipython'))
         except OSError as e:
             if e.errno != errno.ENOENT:
                 raise
         ipdir = path.get_ipython_dir()
         nt.assert_equal(ipdir, IP_TEST_DIR)
 
 @with_environment
 def test_get_ipython_dir_6():
     """test_get_ipython_dir_6, use home over XDG if defined and neither exist."""
     xdg = os.path.join(HOME_TEST_DIR, 'somexdg')
     os.mkdir(xdg)
     shutil.rmtree(os.path.join(HOME_TEST_DIR, '.ipython'))
     with patch_get_home_dir(HOME_TEST_DIR):
         orig_get_xdg_dir = path.get_xdg_dir
         path.get_xdg_dir = lambda : xdg
         try:
             os.name = "posix"
             env.pop('IPYTHON_DIR', None)
             env.pop('IPYTHONDIR', None)
             env.pop('XDG_CONFIG_HOME', None)
             with warnings.catch_warnings(record=True) as w:
                 ipdir = path.get_ipython_dir()
 
             nt.assert_equal(ipdir, os.path.join(HOME_TEST_DIR, '.ipython'))
             nt.assert_equal(len(w), 0)
         finally:
             path.get_xdg_dir = orig_get_xdg_dir
 
 @with_environment
 def test_get_ipython_dir_7():
     """test_get_ipython_dir_7, test home directory expansion on IPYTHONDIR"""
     path._writable_dir = lambda path: True
     home_dir = os.path.normpath(os.path.expanduser('~'))
     env['IPYTHONDIR'] = os.path.join('~', 'somewhere')
     ipdir = path.get_ipython_dir()
     nt.assert_equal(ipdir, os.path.join(home_dir, 'somewhere'))
 
 @skip_win32
 @with_environment
 def test_get_ipython_dir_8():
     """test_get_ipython_dir_8, test / home directory"""
     old = path._writable_dir, path.get_xdg_dir
     try:
         path._writable_dir = lambda path: bool(path)
         path.get_xdg_dir = lambda: None
         env.pop('IPYTHON_DIR', None)
         env.pop('IPYTHONDIR', None)
         env['HOME'] = '/'
         nt.assert_equal(path.get_ipython_dir(), '/.ipython')
     finally:
         path._writable_dir, path.get_xdg_dir = old
 
 @with_environment
 def test_get_xdg_dir_0():
     """test_get_xdg_dir_0, check xdg_dir"""
     reload(path)
     path._writable_dir = lambda path: True
     path.get_home_dir = lambda : 'somewhere'
     os.name = "posix"
     sys.platform = "linux2"
     env.pop('IPYTHON_DIR', None)
     env.pop('IPYTHONDIR', None)
     env.pop('XDG_CONFIG_HOME', None)
 
     nt.assert_equal(path.get_xdg_dir(), os.path.join('somewhere', '.config'))
 
 
 @with_environment
 def test_get_xdg_dir_1():
     """test_get_xdg_dir_1, check nonexistant xdg_dir"""
     reload(path)
     path.get_home_dir = lambda : HOME_TEST_DIR
     os.name = "posix"
     sys.platform = "linux2"
     env.pop('IPYTHON_DIR', None)
     env.pop('IPYTHONDIR', None)
     env.pop('XDG_CONFIG_HOME', None)
     nt.assert_equal(path.get_xdg_dir(), None)
 
 @with_environment
 def test_get_xdg_dir_2():
     """test_get_xdg_dir_2, check xdg_dir default to ~/.config"""
     reload(path)
     path.get_home_dir = lambda : HOME_TEST_DIR
     os.name = "posix"
     sys.platform = "linux2"
     env.pop('IPYTHON_DIR', None)
     env.pop('IPYTHONDIR', None)
     env.pop('XDG_CONFIG_HOME', None)
     cfgdir=os.path.join(path.get_home_dir(), '.config')
     if not os.path.exists(cfgdir):
         os.makedirs(cfgdir)
 
     nt.assert_equal(path.get_xdg_dir(), cfgdir)
 
 @with_environment
 def test_get_xdg_dir_3():
     """test_get_xdg_dir_3, check xdg_dir not used on OS X"""
     reload(path)
     path.get_home_dir = lambda : HOME_TEST_DIR
     os.name = "posix"
     sys.platform = "darwin"
     env.pop('IPYTHON_DIR', None)
     env.pop('IPYTHONDIR', None)
     env.pop('XDG_CONFIG_HOME', None)
     cfgdir=os.path.join(path.get_home_dir(), '.config')
     if not os.path.exists(cfgdir):
         os.makedirs(cfgdir)
 
     nt.assert_equal(path.get_xdg_dir(), None)
 
 def test_filefind():
     """Various tests for filefind"""
     f = tempfile.NamedTemporaryFile()
     # print 'fname:',f.name
     alt_dirs = path.get_ipython_dir()
     t = path.filefind(f.name, alt_dirs)
     # print 'found:',t
 
 @with_environment
 def test_get_ipython_cache_dir():
     os.environ["HOME"] = HOME_TEST_DIR
     if os.name == 'posix' and sys.platform != 'darwin':
         # test default
         os.makedirs(os.path.join(HOME_TEST_DIR, ".cache"))
         os.environ.pop("XDG_CACHE_HOME", None)
         ipdir = path.get_ipython_cache_dir()
         nt.assert_equal(os.path.join(HOME_TEST_DIR, ".cache", "ipython"),
                         ipdir)
         nt.assert_true(os.path.isdir(ipdir))
 
         # test env override
         os.environ["XDG_CACHE_HOME"] = XDG_CACHE_DIR
         ipdir = path.get_ipython_cache_dir()
         nt.assert_true(os.path.isdir(ipdir))
         nt.assert_equal(ipdir, os.path.join(XDG_CACHE_DIR, "ipython"))
     else:
         nt.assert_equal(path.get_ipython_cache_dir(),
                         path.get_ipython_dir())
 
 def test_get_ipython_package_dir():
     ipdir = path.get_ipython_package_dir()
     nt.assert_true(os.path.isdir(ipdir))
 
 
 def test_get_ipython_module_path():
     ipapp_path = path.get_ipython_module_path('IPython.terminal.ipapp')
     nt.assert_true(os.path.isfile(ipapp_path))
 
 
 @dec.skip_if_not_win32
 def test_get_long_path_name_win32():
     with TemporaryDirectory() as tmpdir:
 
         # Make a long path. Expands the path of tmpdir prematurely as it may already have a long 
         # path component, so ensure we include the long form of it
         long_path = os.path.join(path.get_long_path_name(tmpdir), u'this is my long path name')
         os.makedirs(long_path)
 
         # Test to see if the short path evaluates correctly.
         short_path = os.path.join(tmpdir, u'THISIS~1')
         evaluated_path = path.get_long_path_name(short_path)
         nt.assert_equal(evaluated_path.lower(), long_path.lower())
 
 
 @dec.skip_win32
 def test_get_long_path_name():
     p = path.get_long_path_name('/usr/local')
     nt.assert_equal(p,'/usr/local')
 
 @dec.skip_win32 # can't create not-user-writable dir on win
 @with_environment
 def test_not_writable_ipdir():
     tmpdir = tempfile.mkdtemp()
     os.name = "posix"
     env.pop('IPYTHON_DIR', None)
     env.pop('IPYTHONDIR', None)
     env.pop('XDG_CONFIG_HOME', None)
     env['HOME'] = tmpdir
     ipdir = os.path.join(tmpdir, '.ipython')
     os.mkdir(ipdir)
     os.chmod(ipdir, 600)
     with AssertPrints('is not a writable location', channel='stderr'):
         ipdir = path.get_ipython_dir()
     env.pop('IPYTHON_DIR', None)
 
 def test_unquote_filename():
     for win32 in (True, False):
         nt.assert_equal(path.unquote_filename('foo.py', win32=win32), 'foo.py')
         nt.assert_equal(path.unquote_filename('foo bar.py', win32=win32), 'foo bar.py')
     nt.assert_equal(path.unquote_filename('"foo.py"', win32=True), 'foo.py')
     nt.assert_equal(path.unquote_filename('"foo bar.py"', win32=True), 'foo bar.py')
     nt.assert_equal(path.unquote_filename("'foo.py'", win32=True), 'foo.py')
     nt.assert_equal(path.unquote_filename("'foo bar.py'", win32=True), 'foo bar.py')
     nt.assert_equal(path.unquote_filename('"foo.py"', win32=False), '"foo.py"')
     nt.assert_equal(path.unquote_filename('"foo bar.py"', win32=False), '"foo bar.py"')
     nt.assert_equal(path.unquote_filename("'foo.py'", win32=False), "'foo.py'")
     nt.assert_equal(path.unquote_filename("'foo bar.py'", win32=False), "'foo bar.py'")
 
 @with_environment
 def test_get_py_filename():
     os.chdir(TMP_TEST_DIR)
     for win32 in (True, False):
         with make_tempfile('foo.py'):
             nt.assert_equal(path.get_py_filename('foo.py', force_win32=win32), 'foo.py')
             nt.assert_equal(path.get_py_filename('foo', force_win32=win32), 'foo.py')
         with make_tempfile('foo'):
             nt.assert_equal(path.get_py_filename('foo', force_win32=win32), 'foo')
             nt.assert_raises(IOError, path.get_py_filename, 'foo.py', force_win32=win32)
         nt.assert_raises(IOError, path.get_py_filename, 'foo', force_win32=win32)
         nt.assert_raises(IOError, path.get_py_filename, 'foo.py', force_win32=win32)
         true_fn = 'foo with spaces.py'
         with make_tempfile(true_fn):
             nt.assert_equal(path.get_py_filename('foo with spaces', force_win32=win32), true_fn)
             nt.assert_equal(path.get_py_filename('foo with spaces.py', force_win32=win32), true_fn)
             if win32:
                 nt.assert_equal(path.get_py_filename('"foo with spaces.py"', force_win32=True), true_fn)
                 nt.assert_equal(path.get_py_filename("'foo with spaces.py'", force_win32=True), true_fn)
             else:
                 nt.assert_raises(IOError, path.get_py_filename, '"foo with spaces.py"', force_win32=False)
                 nt.assert_raises(IOError, path.get_py_filename, "'foo with spaces.py'", force_win32=False)
 
 @onlyif_unicode_paths
 def test_unicode_in_filename():
     """When a file doesn't exist, the exception raised should be safe to call
     str() on - i.e. in Python 2 it must only have ASCII characters.
     
     https://github.com/ipython/ipython/issues/875
     """
     try:
         # these calls should not throw unicode encode exceptions
         path.get_py_filename(u'fooéè.py',  force_win32=False)
     except IOError as ex:
         str(ex)
 
 
 class TestShellGlob(object):
 
     @classmethod
     def setUpClass(cls):
         cls.filenames_start_with_a = ['a0', 'a1', 'a2']
         cls.filenames_end_with_b = ['0b', '1b', '2b']
         cls.filenames = cls.filenames_start_with_a + cls.filenames_end_with_b
         cls.tempdir = TemporaryDirectory()
         td = cls.tempdir.name
 
         with cls.in_tempdir():
             # Create empty files
             for fname in cls.filenames:
                 open(os.path.join(td, fname), 'w').close()
 
     @classmethod
     def tearDownClass(cls):
         cls.tempdir.cleanup()
 
     @classmethod
     @contextmanager
     def in_tempdir(cls):
         save = py3compat.getcwd()
         try:
             os.chdir(cls.tempdir.name)
             yield
         finally:
             os.chdir(save)
 
     def check_match(self, patterns, matches):
         with self.in_tempdir():
             # glob returns unordered list. that's why sorted is required.
             nt.assert_equals(sorted(path.shellglob(patterns)),
                              sorted(matches))
 
     def common_cases(self):
         return [
             (['*'], self.filenames),
             (['a*'], self.filenames_start_with_a),
             (['*c'], ['*c']),
             (['*', 'a*', '*b', '*c'], self.filenames
                                       + self.filenames_start_with_a
                                       + self.filenames_end_with_b
                                       + ['*c']),
             (['a[012]'], self.filenames_start_with_a),
         ]
 
     @skip_win32
     def test_match_posix(self):
         for (patterns, matches) in self.common_cases() + [
                 ([r'\*'], ['*']),
                 ([r'a\*', 'a*'], ['a*'] + self.filenames_start_with_a),
                 ([r'a\[012]'], ['a[012]']),
                 ]:
             yield (self.check_match, patterns, matches)
 
     @skip_if_not_win32
     def test_match_windows(self):
         for (patterns, matches) in self.common_cases() + [
                 # In windows, backslash is interpreted as path
                 # separator.  Therefore, you can't escape glob
                 # using it.
                 ([r'a\*', 'a*'], [r'a\*'] + self.filenames_start_with_a),
                 ([r'a\[012]'], [r'a\[012]']),
                 ]:
             yield (self.check_match, patterns, matches)
 
 
 def test_unescape_glob():
     nt.assert_equals(path.unescape_glob(r'\*\[\!\]\?'), '*[!]?')
     nt.assert_equals(path.unescape_glob(r'\\*'), r'\*')
     nt.assert_equals(path.unescape_glob(r'\\\*'), r'\*')
     nt.assert_equals(path.unescape_glob(r'\\a'), r'\a')
     nt.assert_equals(path.unescape_glob(r'\a'), r'\a')
 
 
 class TestLinkOrCopy(object):
     def setUp(self):
         self.tempdir = TemporaryDirectory()
         self.src = self.dst("src")
         with open(self.src, "w") as f:
             f.write("Hello, world!")
 
     def tearDown(self):
         self.tempdir.cleanup()
 
     def dst(self, *args):
         return os.path.join(self.tempdir.name, *args)
 
     def assert_inode_not_equal(self, a, b):
         nt.assert_not_equals(os.stat(a).st_ino, os.stat(b).st_ino,
                              "%r and %r do reference the same indoes" %(a, b))
 
     def assert_inode_equal(self, a, b):
         nt.assert_equals(os.stat(a).st_ino, os.stat(b).st_ino,
                          "%r and %r do not reference the same indoes" %(a, b))
 
     def assert_content_equal(self, a, b):
         with open(a) as a_f:
             with open(b) as b_f:
                 nt.assert_equals(a_f.read(), b_f.read())
 
     @skip_win32
     def test_link_successful(self):
         dst = self.dst("target")
         path.link_or_copy(self.src, dst)
         self.assert_inode_equal(self.src, dst)
 
     @skip_win32
     def test_link_into_dir(self):
         dst = self.dst("some_dir")
         os.mkdir(dst)
         path.link_or_copy(self.src, dst)
         expected_dst = self.dst("some_dir", os.path.basename(self.src))
         self.assert_inode_equal(self.src, expected_dst)
 
     @skip_win32
     def test_target_exists(self):
         dst = self.dst("target")
         open(dst, "w").close()
         path.link_or_copy(self.src, dst)
         self.assert_inode_equal(self.src, dst)
 
     @skip_win32
     def test_no_link(self):
         real_link = os.link
         try:
             del os.link
             dst = self.dst("target")
             path.link_or_copy(self.src, dst)
             self.assert_content_equal(self.src, dst)
             self.assert_inode_not_equal(self.src, dst)
         finally:
             os.link = real_link
 
     @skip_if_not_win32
     def test_windows(self):
         dst = self.dst("target")
         path.link_or_copy(self.src, dst)
         self.assert_content_equal(self.src, dst)