Fix DeprecationWarning on Windows

Issue #25911: Use support.check_warnings() to expect or ignore
DeprecationWarning in test_os.

Lib/test/test_os.py

@@ -66,6 +66,7 @@ except ImportError:
 
 from test.support.script_helper import assert_python_ok
 
+
 root_in_posix = False
 if hasattr(os, 'geteuid'):
     root_in_posix = (os.geteuid() == 0)
@@ -82,6 +83,23 @@ else:
 # Issue #14110: Some tests fail on FreeBSD if the user is in the wheel group.
 HAVE_WHEEL_GROUP = sys.platform.startswith('freebsd') and os.getgid() == 0
 
+
+@contextlib.contextmanager
+def ignore_deprecation_warnings(msg_regex, quiet=False):
+    with support.check_warnings((msg_regex, DeprecationWarning), quiet=quiet):
+        yield
+
+
+@contextlib.contextmanager
+def bytes_filename_warn(expected):
+    msg = 'The Windows bytes API has been deprecated'
+    if os.name == 'nt':
+        with ignore_deprecation_warnings(msg, quiet=not expected):
+            yield
+    else:
+        yield
+
+
 # Tests creating TESTFN
 class FileTests(unittest.TestCase):
     def setUp(self):
@@ -305,8 +323,7 @@ class StatAttributeTests(unittest.TestCase):
             fname = self.fname.encode(sys.getfilesystemencoding())
         except UnicodeEncodeError:
             self.skipTest("cannot encode %a for the filesystem" % self.fname)
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
+        with bytes_filename_warn(True):
             self.check_stat_attributes(fname)
 
     def test_stat_result_pickle(self):
@@ -443,15 +460,11 @@ class UtimeTests(unittest.TestCase):
             fp.write(b"ABC")
 
         def restore_float_times(state):
-            with warnings.catch_warnings():
-                warnings.simplefilter("ignore", DeprecationWarning)
-
+            with ignore_deprecation_warnings('stat_float_times'):
                 os.stat_float_times(state)
 
         # ensure that st_atime and st_mtime are float
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
-
+        with ignore_deprecation_warnings('stat_float_times'):
             old_float_times = os.stat_float_times(-1)
             self.addCleanup(restore_float_times, old_float_times)
 
@@ -1024,8 +1037,7 @@ class BytesWalkTests(WalkTests):
         super().setUp()
         self.stack = contextlib.ExitStack()
         if os.name == 'nt':
-            self.stack.enter_context(warnings.catch_warnings())
-            warnings.simplefilter("ignore", DeprecationWarning)
+            self.stack.enter_context(bytes_filename_warn(False))
 
     def tearDown(self):
         self.stack.close()
@@ -1580,8 +1592,7 @@ class LinkTests(unittest.TestCase):
         with open(file1, "w") as f1:
             f1.write("test")
 
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
+        with bytes_filename_warn(False):
             os.link(file1, file2)
         with open(file1, "r") as f1, open(file2, "r") as f2:
             self.assertTrue(os.path.sameopenfile(f1.fileno(), f2.fileno()))
@@ -1873,7 +1884,9 @@ class Win32ListdirTests(unittest.TestCase):
         self.assertEqual(
                 sorted(os.listdir(support.TESTFN)),
                 self.created_paths)
+
         # bytes
+        with bytes_filename_warn(False):
             self.assertEqual(
                     sorted(os.listdir(os.fsencode(support.TESTFN))),
                     [os.fsencode(path) for path in self.created_paths])
@@ -1886,7 +1899,9 @@ class Win32ListdirTests(unittest.TestCase):
         self.assertEqual(
                 sorted(os.listdir(path)),
                 self.created_paths)
+
         # bytes
+        with bytes_filename_warn(False):
             path = b'\\\\?\\' + os.fsencode(os.path.abspath(support.TESTFN))
             self.assertEqual(
                     sorted(os.listdir(path)),
@@ -1965,9 +1980,9 @@ class Win32SymlinkTests(unittest.TestCase):
         self.assertNotEqual(os.lstat(link), os.stat(link))
 
         bytes_link = os.fsencode(link)
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
+        with bytes_filename_warn(True):
             self.assertEqual(os.stat(bytes_link), os.stat(target))
+        with bytes_filename_warn(True):
             self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
 
     def test_12084(self):
@@ -2529,8 +2544,6 @@ class Win32DeprecatedBytesAPI(unittest.TestCase):
     def test_deprecated(self):
         import nt
         filename = os.fsencode(support.TESTFN)
-        with warnings.catch_warnings():
-            warnings.simplefilter("error", DeprecationWarning)
         for func, *args in (
             (nt._getfullpathname, filename),
             (nt._isdir, filename),
@@ -2550,15 +2563,18 @@ class Win32DeprecatedBytesAPI(unittest.TestCase):
             (os.unlink, filename),
             (os.utime, filename),
         ):
-                self.assertRaises(DeprecationWarning, func, *args)
+            with bytes_filename_warn(True):
+                try:
+                    func(*args)
+                except OSError:
+                    # ignore OSError, we only care about DeprecationWarning
+                    pass
 
     @support.skip_unless_symlink
     def test_symlink(self):
         filename = os.fsencode(support.TESTFN)
-        with warnings.catch_warnings():
-            warnings.simplefilter("error", DeprecationWarning)
-            self.assertRaises(DeprecationWarning,
-                              os.symlink, filename, filename)
+        with bytes_filename_warn(True):
+            os.symlink(filename, filename)
 
 
 @unittest.skipUnless(hasattr(os, 'get_terminal_size'), "requires os.get_terminal_size")
@@ -2696,6 +2712,7 @@ class OSErrorTests(unittest.TestCase):
         for filenames, func, *func_args in funcs:
             for name in filenames:
                 try:
+                    with bytes_filename_warn(False):
                         func(name, *func_args)
                 except OSError as err:
                     self.assertIs(err.filename, name)
@@ -3011,6 +3028,7 @@ class TestScandir(unittest.TestCase):
     def test_bytes(self):
         if os.name == "nt":
             # On Windows, os.scandir(bytes) must raise an exception
+            with bytes_filename_warn(True):
                 self.assertRaises(TypeError, os.scandir, b'.')
             return