gh-139322: Remove redundant test_os.Win32ErrorTests (#139477)

test_os.OSErrorTests already covers the OSError class and is more
complete than Win32ErrorTests.

Lib/test/test_os/test_os.py

@@ -4080,6 +4080,7 @@ def test_oserror_filename(self):
             (self.filenames, os.listdir,),
             (self.filenames, os.rename, "dst"),
             (self.filenames, os.replace, "dst"),
+            (self.filenames, os.utime, None),
         ]
         if os_helper.can_chmod():
             funcs.append((self.filenames, os.chmod, 0o777))
@@ -4120,6 +4121,19 @@ def test_oserror_filename(self):
                 else:
                     self.fail(f"No exception thrown by {func}")
 
+    def test_mkdir(self):
+        filename = os_helper.TESTFN
+        subdir = os.path.join(filename, 'subdir')
+        self.assertRaises(FileNotFoundError, os.mkdir, subdir)
+
+        self.addCleanup(os_helper.unlink, filename)
+        create_file(filename)
+        self.assertRaises(FileExistsError, os.mkdir, filename)
+
+        self.assertRaises((NotADirectoryError, FileNotFoundError),
+                          os.mkdir, subdir)
+
+
 class CPUCountTests(unittest.TestCase):
     def check_cpu_count(self, cpus):
         if cpus is None:

Lib/test/test_os/test_windows.py

@@ -21,41 +21,6 @@
 from .utils import create_file
 
 
-class Win32ErrorTests(unittest.TestCase):
-    def setUp(self):
-        try:
-            os.stat(os_helper.TESTFN)
-        except FileNotFoundError:
-            exists = False
-        except OSError as exc:
-            exists = True
-            self.fail("file %s must not exist; os.stat failed with %s"
-                      % (os_helper.TESTFN, exc))
-        else:
-            self.fail("file %s must not exist" % os_helper.TESTFN)
-
-    def test_rename(self):
-        self.assertRaises(OSError, os.rename, os_helper.TESTFN, os_helper.TESTFN+".bak")
-
-    def test_remove(self):
-        self.assertRaises(OSError, os.remove, os_helper.TESTFN)
-
-    def test_chdir(self):
-        self.assertRaises(OSError, os.chdir, os_helper.TESTFN)
-
-    def test_mkdir(self):
-        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
-
-        with open(os_helper.TESTFN, "x") as f:
-            self.assertRaises(OSError, os.mkdir, os_helper.TESTFN)
-
-    def test_utime(self):
-        self.assertRaises(OSError, os.utime, os_helper.TESTFN, None)
-
-    def test_chmod(self):
-        self.assertRaises(OSError, os.chmod, os_helper.TESTFN, 0)
-
-
 class Win32KillTests(unittest.TestCase):
     def _kill(self, sig):
         # Start sys.executable as a subprocess and communicate from the