Python test.support.swap_attr() Examples

def test_record_override_showwarning_before(self):
        # Issue #28835: If warnings.showwarning() was overridden, make sure
        # that catch_warnings(record=True) overrides it again.
        text = "This is a warning"
        wmod = self.module
        my_log = []

        def my_logger(message, category, filename, lineno, file=None, line=None):
            nonlocal my_log
            my_log.append(message)

        # Override warnings.showwarning() before calling catch_warnings()
        with support.swap_attr(wmod, 'showwarning', my_logger):
            with wmod.catch_warnings(module=wmod, record=True) as log:
                self.assertIsNot(wmod.showwarning, my_logger)

                wmod.simplefilter("always")
                wmod.warn(text)

            self.assertIs(wmod.showwarning, my_logger)

        self.assertEqual(len(log), 1, log)
        self.assertEqual(log[0].message.args[0], text)
        self.assertEqual(my_log, []) 

def test_swap_attr(self):
        class Obj:
            pass
        obj = Obj()
        obj.x = 1
        with support.swap_attr(obj, "x", 5) as x:
            self.assertEqual(obj.x, 5)
            self.assertEqual(x, 1)
        self.assertEqual(obj.x, 1)
        with support.swap_attr(obj, "y", 5) as y:
            self.assertEqual(obj.y, 5)
            self.assertIsNone(y)
        self.assertFalse(hasattr(obj, 'y'))
        with support.swap_attr(obj, "y", 5):
            del obj.y
        self.assertFalse(hasattr(obj, 'y')) 

def test_list_verbose(self):
        tio = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
        with support.swap_attr(sys, 'stdout', tio):
            self.tar.list(verbose=True)
        out = tio.detach().getvalue()
        # Make sure it prints files separated by one newline with 'ls -l'-like
        # accessories if verbose flag is being used
        # ...
        # ?rw-r--r-- tarfile/tarfile     7011 2003-01-06 07:19:43 ustar/conttype
        # ?rw-r--r-- tarfile/tarfile     7011 2003-01-06 07:19:43 ustar/regtype
        # ...
        self.assertRegex(out, (br'\?rw-r--r-- tarfile/tarfile\s+7011 '
                               br'\d{4}-\d\d-\d\d\s+\d\d:\d\d:\d\d '
                               br'ustar/\w+type ?\r?\n') * 2)
        # Make sure it prints the source of link with verbose flag
        self.assertIn(b'ustar/symtype -> regtype', out)
        self.assertIn(b'./ustar/linktest2/symtype -> ../linktest1/regtype', out)
        self.assertIn(b'./ustar/linktest2/lnktype link to '
                      b'./ustar/linktest1/regtype', out)
        self.assertIn(b'gnu' + (b'/123' * 125) + b'/longlink link to gnu' +
                      (b'/123' * 125) + b'/longname', out)
        self.assertIn(b'pax' + (b'/123' * 125) + b'/longlink link to pax' +
                      (b'/123' * 125) + b'/longname', out) 

def test_rmtree(self):
        dirpath = support.TESTFN + 'd'
        subdirpath = os.path.join(dirpath, 'subdir')
        os.mkdir(dirpath)
        os.mkdir(subdirpath)
        support.rmtree(dirpath)
        self.assertFalse(os.path.exists(dirpath))
        with support.swap_attr(support, 'verbose', 0):
            support.rmtree(dirpath)

        os.mkdir(dirpath)
        os.mkdir(subdirpath)
        os.chmod(dirpath, stat.S_IRUSR|stat.S_IXUSR)
        with support.swap_attr(support, 'verbose', 0):
            support.rmtree(dirpath)
        self.assertFalse(os.path.exists(dirpath))

        os.mkdir(dirpath)
        os.mkdir(subdirpath)
        os.chmod(dirpath, 0)
        with support.swap_attr(support, 'verbose', 0):
            support.rmtree(dirpath)
        self.assertFalse(os.path.exists(dirpath)) 

def test_modify_builtins_from_leaf_function(self):
        # Verify that modifications made by leaf functions percolate up the
        # callstack.
        with swap_attr(builtins, "len", len):
            def bar():
                builtins.len = lambda x: 4

            def foo(modifier):
                l = []
                l.append(len(range(7)))
                modifier()
                l.append(len(range(7)))
                return l
            self.configure_func(foo, lambda: None)

            self.assertEqual(foo(bar), [7, 4]) 

def test_bad_timezone(self):
        # Explicitly test possibility of bad timezone;
        # when time.tzname[0] == time.tzname[1] and time.daylight
        tz_name = time.tzname[0]
        if tz_name.upper() in ("UTC", "GMT"):
            self.skipTest('need non-UTC/GMT timezone')

        with support.swap_attr(time, 'tzname', (tz_name, tz_name)), \
             support.swap_attr(time, 'daylight', 1), \
             support.swap_attr(time, 'tzset', lambda: None):
            time.tzname = (tz_name, tz_name)
            time.daylight = 1
            tz_value = _strptime._strptime_time(tz_name, "%Z")[8]
            self.assertEqual(tz_value, -1,
                    "%s lead to a timezone value of %s instead of -1 when "
                    "time.daylight set to %s and passing in %s" %
                    (time.tzname, tz_value, time.daylight, tz_name)) 

def test_windows_colon(self):
        with support.swap_attr(server.os, 'path', ntpath):
            path = self.handler.translate_path('c:c:c:foo/filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated)

            path = self.handler.translate_path('\\c:../filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated)

            path = self.handler.translate_path('c:\\c:..\\foo/filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated)

            path = self.handler.translate_path('c:c:foo\\c:c:bar/filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated) 

def test_list_verbose(self):
        tio = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
        with support.swap_attr(sys, 'stdout', tio):
            self.tar.list(verbose=True)
        out = tio.detach().getvalue()
        # Make sure it prints files separated by one newline with 'ls -l'-like
        # accessories if verbose flag is being used
        # ...
        # ?rw-r--r-- tarfile/tarfile     7011 2003-01-06 07:19:43 ustar/conttype
        # ?rw-r--r-- tarfile/tarfile     7011 2003-01-06 07:19:43 ustar/regtype
        # ...
        self.assertRegex(out, (br'\?rw-r--r-- tarfile/tarfile\s+7011 '
                               br'\d{4}-\d\d-\d\d\s+\d\d:\d\d:\d\d '
                               br'ustar/\w+type ?\r?\n') * 2)
        # Make sure it prints the source of link with verbose flag
        self.assertIn(b'ustar/symtype -> regtype', out)
        self.assertIn(b'./ustar/linktest2/symtype -> ../linktest1/regtype', out)
        self.assertIn(b'./ustar/linktest2/lnktype link to '
                      b'./ustar/linktest1/regtype', out)
        self.assertIn(b'gnu' + (b'/123' * 125) + b'/longlink link to gnu' +
                      (b'/123' * 125) + b'/longname', out)
        self.assertIn(b'pax' + (b'/123' * 125) + b'/longlink link to pax' +
                      (b'/123' * 125) + b'/longname', out) 

def test_modify_builtins_from_leaf_function(self):
        # Verify that modifications made by leaf functions percolate up the
        # callstack.
        with swap_attr(builtins, "len", len):
            def bar():
                builtins.len = lambda x: 4

            def foo(modifier):
                l = []
                l.append(len(range(7)))
                modifier()
                l.append(len(range(7)))
                return l
            self.configure_func(foo, lambda: None)

            self.assertEqual(foo(bar), [7, 4]) 

def test_rmtree(self):
        dirpath = support.TESTFN + 'd'
        subdirpath = os.path.join(dirpath, 'subdir')
        os.mkdir(dirpath)
        os.mkdir(subdirpath)
        support.rmtree(dirpath)
        self.assertFalse(os.path.exists(dirpath))
        with support.swap_attr(support, 'verbose', 0):
            support.rmtree(dirpath)

        os.mkdir(dirpath)
        os.mkdir(subdirpath)
        os.chmod(dirpath, stat.S_IRUSR|stat.S_IXUSR)
        with support.swap_attr(support, 'verbose', 0):
            support.rmtree(dirpath)
        self.assertFalse(os.path.exists(dirpath))

        os.mkdir(dirpath)
        os.mkdir(subdirpath)
        os.chmod(dirpath, 0)
        with support.swap_attr(support, 'verbose', 0):
            support.rmtree(dirpath)
        self.assertFalse(os.path.exists(dirpath)) 

def test_swap_attr(self):
        class Obj:
            pass
        obj = Obj()
        obj.x = 1
        with support.swap_attr(obj, "x", 5) as x:
            self.assertEqual(obj.x, 5)
            self.assertEqual(x, 1)
        self.assertEqual(obj.x, 1)
        with support.swap_attr(obj, "y", 5) as y:
            self.assertEqual(obj.y, 5)
            self.assertIsNone(y)
        self.assertFalse(hasattr(obj, 'y'))
        with support.swap_attr(obj, "y", 5):
            del obj.y
        self.assertFalse(hasattr(obj, 'y')) 

def test_windows_colon(self):
        with support.swap_attr(server.os, 'path', ntpath):
            path = self.handler.translate_path('c:c:c:foo/filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated)

            path = self.handler.translate_path('\\c:../filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated)

            path = self.handler.translate_path('c:\\c:..\\foo/filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated)

            path = self.handler.translate_path('c:c:foo\\c:c:bar/filename')
            path = path.replace(ntpath.sep, os.sep)
            self.assertEqual(path, self.translated) 

def test_list_verbose(self):
        tio = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
        with support.swap_attr(sys, 'stdout', tio):
            self.tar.list(verbose=True)
        out = tio.detach().getvalue()
        # Make sure it prints files separated by one newline with 'ls -l'-like
        # accessories if verbose flag is being used
        # ...
        # ?rw-r--r-- tarfile/tarfile     7011 2003-01-06 07:19:43 ustar/conttype
        # ?rw-r--r-- tarfile/tarfile     7011 2003-01-06 07:19:43 ustar/regtype
        # ...
        self.assertRegex(out, (br'\?rw-r--r-- tarfile/tarfile\s+7011 '
                               br'\d{4}-\d\d-\d\d\s+\d\d:\d\d:\d\d '
                               br'ustar/\w+type ?\r?\n') * 2)
        # Make sure it prints the source of link with verbose flag
        self.assertIn(b'ustar/symtype -> regtype', out)
        self.assertIn(b'./ustar/linktest2/symtype -> ../linktest1/regtype', out)
        self.assertIn(b'./ustar/linktest2/lnktype link to '
                      b'./ustar/linktest1/regtype', out)
        self.assertIn(b'gnu' + (b'/123' * 125) + b'/longlink link to gnu' +
                      (b'/123' * 125) + b'/longname', out)
        self.assertIn(b'pax' + (b'/123' * 125) + b'/longlink link to pax' +
                      (b'/123' * 125) + b'/longname', out) 

def test_modify_builtins_from_leaf_function(self):
        # Verify that modifications made by leaf functions percolate up the
        # callstack.
        with swap_attr(builtins, "len", len):
            def bar():
                builtins.len = lambda x: 4

            def foo(modifier):
                l = []
                l.append(len(range(7)))
                modifier()
                l.append(len(range(7)))
                return l
            self.configure_func(foo, lambda: None)

            self.assertEqual(foo(bar), [7, 4]) 

def test_fallback(self):
        with support.EnvironmentVarGuard() as env:
            del env['LINES']
            del env['COLUMNS']

            # sys.__stdout__ has no fileno()
            with support.swap_attr(sys, '__stdout__', None):
                size = shutil.get_terminal_size(fallback=(10, 20))
            self.assertEqual(size.columns, 10)
            self.assertEqual(size.lines, 20)

            # sys.__stdout__ is not a terminal on Unix
            # or fileno() not in (0, 1, 2) on Windows
            with open(os.devnull, 'w') as f, \
                 support.swap_attr(sys, '__stdout__', f):
                size = shutil.get_terminal_size(fallback=(30, 40))
            self.assertEqual(size.columns, 30)
            self.assertEqual(size.lines, 40) 

def test_home_not_set(self):
        fake_home = support.TESTFN
        os.mkdir(fake_home)
        self.addCleanup(support.rmtree, fake_home)
        fake_netrc_path = os.path.join(fake_home, '.netrc')
        with open(fake_netrc_path, 'w') as f:
            f.write('machine foo.domain.com login bar password pass')
        os.chmod(fake_netrc_path, 0o600)

        orig_expanduser = os.path.expanduser
        called = []

        def fake_expanduser(s):
            called.append(s)
            with support.EnvironmentVarGuard() as environ:
                environ.set('HOME', fake_home)
                result = orig_expanduser(s)
                return result

        with support.swap_attr(os.path, 'expanduser', fake_expanduser):
            nrc = netrc.netrc()
            login, account, password = nrc.authenticators('foo.domain.com')
            self.assertEqual(login, 'bar')

        self.assertTrue(called) 

def test_formatwarning_override(self):
        # bpo-35178: Test that a custom formatwarning function gets the 'line'
        # argument as a positional argument, and not only as a keyword argument
        def myformatwarning(message, category, filename, lineno, text):
            return f'm={message}:c={category}:f={filename}:l={lineno}:t={text}'

        file_name = os.path.splitext(warning_tests.__file__)[0] + '.py'
        line_num = 3
        file_line = linecache.getline(file_name, line_num).strip()
        message = 'msg'
        category = Warning
        file_object = StringIO()
        expected = f'm={message}:c={category}:f={file_name}:l={line_num}' + \
                   f':t={file_line}'
        with support.swap_attr(self.module, 'formatwarning', myformatwarning):
            self.module.showwarning(message, category, file_name, line_num,
                                    file_object, file_line)
            self.assertEqual(file_object.getvalue(), expected) 

def test_no_files_left_behind(self):
        # use a private empty directory
        with tempfile.TemporaryDirectory() as our_temp_directory:
            # force _get_default_tempdir() to consider our empty directory
            def our_candidate_list():
                return [our_temp_directory]

            with support.swap_attr(tempfile, "_candidate_tempdir_list",
                                   our_candidate_list):
                # verify our directory is empty after _get_default_tempdir()
                tempfile._get_default_tempdir()
                self.assertEqual(os.listdir(our_temp_directory), [])

                def raise_OSError(*args, **kwargs):
                    raise OSError()

                with support.swap_attr(io, "open", raise_OSError):
                    # test again with failing io.open()
                    with self.assertRaises(FileNotFoundError):
                        tempfile._get_default_tempdir()
                    self.assertEqual(os.listdir(our_temp_directory), [])

                def bad_writer(*args, **kwargs):
                    fp = orig_open(*args, **kwargs)
                    fp.write = raise_OSError
                    return fp

                with support.swap_attr(io, "open", bad_writer) as orig_open:
                    # test again with failing write()
                    with self.assertRaises(FileNotFoundError):
                        tempfile._get_default_tempdir()
                    self.assertEqual(os.listdir(our_temp_directory), []) 

def test_non_directory(self):
        with _inside_empty_temp_dir():
            tempdir = os.path.join(tempfile.tempdir, 'file')
            open(tempdir, 'wb').close()
            with support.swap_attr(tempfile, 'tempdir', tempdir):
                with self.assertRaises((NotADirectoryError, FileNotFoundError)):
                    self.make_temp() 

def test_swap_attr(self):
        class Obj:
            x = 1
        obj = Obj()
        with support.swap_attr(obj, "x", 5):
            self.assertEqual(obj.x, 5)
        self.assertEqual(obj.x, 1) 

def test_no_files_left_behind(self):
        # use a private empty directory
        with tempfile.TemporaryDirectory() as our_temp_directory:
            # force _get_default_tempdir() to consider our empty directory
            def our_candidate_list():
                return [our_temp_directory]

            with support.swap_attr(tempfile, "_candidate_tempdir_list",
                                   our_candidate_list):
                # verify our directory is empty after _get_default_tempdir()
                tempfile._get_default_tempdir()
                self.assertEqual(os.listdir(our_temp_directory), [])

                def raise_OSError(*args, **kwargs):
                    raise OSError()

                with support.swap_attr(io, "open", raise_OSError):
                    # test again with failing io.open()
                    with self.assertRaises(FileNotFoundError):
                        tempfile._get_default_tempdir()
                    self.assertEqual(os.listdir(our_temp_directory), [])

                open = io.open
                def bad_writer(*args, **kwargs):
                    fp = open(*args, **kwargs)
                    fp.write = raise_OSError
                    return fp

                with support.swap_attr(io, "open", bad_writer):
                    # test again with failing write()
                    with self.assertRaises(FileNotFoundError):
                        tempfile._get_default_tempdir()
                    self.assertEqual(os.listdir(our_temp_directory), []) 

def _inside_empty_temp_dir():
    dir = tempfile.mkdtemp()
    try:
        with support.swap_attr(tempfile, 'tempdir', dir):
            yield
    finally:
        support.rmtree(dir) 

def test_memoryerror(self):
        lines = linecache.getlines(FILENAME)
        self.assertTrue(lines)
        def raise_memoryerror(*args, **kwargs):
            raise MemoryError
        with support.swap_attr(linecache, 'updatecache', raise_memoryerror):
            lines2 = linecache.getlines(FILENAME)
        self.assertEqual(lines2, lines)

        linecache.clearcache()
        with support.swap_attr(linecache, 'updatecache', raise_memoryerror):
            lines3 = linecache.getlines(FILENAME)
        self.assertEqual(lines3, [])
        self.assertEqual(linecache.getlines(FILENAME), lines) 

def test_list(self):
        tio = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
        with support.swap_attr(sys, 'stdout', tio):
            self.tar.list(verbose=False)
        out = tio.detach().getvalue()
        self.assertIn(b'ustar/conttype', out)
        self.assertIn(b'ustar/regtype', out)
        self.assertIn(b'ustar/lnktype', out)
        self.assertIn(b'ustar' + (b'/12345' * 40) + b'67/longname', out)
        self.assertIn(b'./ustar/linktest2/symtype', out)
        self.assertIn(b'./ustar/linktest2/lnktype', out)
        # Make sure it puts trailing slash for directory
        self.assertIn(b'ustar/dirtype/', out)
        self.assertIn(b'ustar/dirtype-with-size/', out)
        # Make sure it is able to print unencodable characters
        def conv(b):
            s = b.decode(self.tar.encoding, 'surrogateescape')
            return s.encode('ascii', 'backslashreplace')
        self.assertIn(conv(b'ustar/umlauts-\xc4\xd6\xdc\xe4\xf6\xfc\xdf'), out)
        self.assertIn(conv(b'misc/regtype-hpux-signed-chksum-'
                           b'\xc4\xd6\xdc\xe4\xf6\xfc\xdf'), out)
        self.assertIn(conv(b'misc/regtype-old-v7-signed-chksum-'
                           b'\xc4\xd6\xdc\xe4\xf6\xfc\xdf'), out)
        self.assertIn(conv(b'pax/bad-pax-\xe4\xf6\xfc'), out)
        self.assertIn(conv(b'pax/hdrcharset-\xe4\xf6\xfc'), out)
        # Make sure it prints files separated by one newline without any
        # 'ls -l'-like accessories if verbose flag is not being used
        # ...
        # ustar/conttype
        # ustar/regtype
        # ...
        self.assertRegex(out, br'ustar/conttype ?\r?\n'
                              br'ustar/regtype ?\r?\n')
        # Make sure it does not print the source of link without verbose flag
        self.assertNotIn(b'link to', out)
        self.assertNotIn(b'->', out) 

def test_no_home_directory(self):
        # bpo-10496: getuserbase() and getusersitepackages() must not fail if
        # the current user has no home directory (if expanduser() returns the
        # path unchanged).
        site.USER_SITE = None
        site.USER_BASE = None
        sysconfig._CONFIG_VARS = None

        with EnvironmentVarGuard() as environ, \
             support.swap_attr(os.path, 'expanduser', lambda path: path):

            del environ['PYTHONUSERBASE']
            del environ['APPDATA']

            user_base = site.getuserbase()
            self.assertTrue(user_base.startswith('~' + os.sep),
                            user_base)

            user_site = site.getusersitepackages()
            self.assertTrue(user_site.startswith(user_base), user_site)

        def fake_isdir(path):
            fake_isdir.arg = path
            return False
        fake_isdir.arg = None

        def must_not_be_called(*args):
            raise AssertionError

        with support.swap_attr(os.path, 'isdir', fake_isdir), \
             support.swap_attr(site, 'addsitedir', must_not_be_called), \
             support.swap_attr(site, 'ENABLE_USER_SITE', True):

            # addusersitepackages() must not add user_site to sys.path
            # if it is not an existing directory
            known_paths = set()
            site.addusersitepackages(known_paths)

            self.assertEqual(fake_isdir.arg, user_site)
            self.assertFalse(known_paths) 

def test_list_members(self):
        tio = io.TextIOWrapper(io.BytesIO(), 'ascii', newline='\n')
        def members(tar):
            for tarinfo in tar.getmembers():
                if 'reg' in tarinfo.name:
                    yield tarinfo
        with support.swap_attr(sys, 'stdout', tio):
            self.tar.list(verbose=False, members=members(self.tar))
        out = tio.detach().getvalue()
        self.assertIn(b'ustar/regtype', out)
        self.assertNotIn(b'ustar/conttype', out) 

def test_modify_builtins(self):
        # Modify the builtins module directly.
        def foo():
            return len([1, 2, 3])
        self.configure_func(foo)

        self.assertEqual(foo(), 3)
        with swap_attr(builtins, "len", lambda x: 7):
            self.assertEqual(foo(), 7) 

def test_apop_REDOS(self):
        # Replace welcome with very long evil welcome.
        # NB The upper bound on welcome length is currently 2048.
        # At this length, evil input makes each apop call take
        # on the order of milliseconds instead of microseconds.
        evil_welcome = b'+OK' + (b'<' * 1000000)
        with test_support.swap_attr(self.client, 'welcome', evil_welcome):
            # The evil welcome is invalid, so apop should throw.
            self.assertRaises(poplib.error_proto, self.client.apop, 'a', 'kb') 

def test_memoryerror(self):
        lines = linecache.getlines(FILENAME)
        self.assertTrue(lines)
        def raise_memoryerror(*args, **kwargs):
            raise MemoryError
        with support.swap_attr(linecache, 'updatecache', raise_memoryerror):
            lines2 = linecache.getlines(FILENAME)
        self.assertEqual(lines2, lines)

        linecache.clearcache()
        with support.swap_attr(linecache, 'updatecache', raise_memoryerror):
            lines3 = linecache.getlines(FILENAME)
        self.assertEqual(lines3, [])
        self.assertEqual(linecache.getlines(FILENAME), lines) 

def test_nonexisting_directory(self):
        with _inside_empty_temp_dir():
            tempdir = os.path.join(tempfile.tempdir, 'nonexistent')
            with support.swap_attr(tempfile, 'tempdir', tempdir):
                with self.assertRaises(FileNotFoundError):
                    self.make_temp()