diff --git a/Doc/library/shutil.rst b/Doc/library/shutil.rst
index 028778d56518f8..08128f8711b451 100644
--- a/Doc/library/shutil.rst
+++ b/Doc/library/shutil.rst
@@ -481,12 +481,6 @@ Directory and files operations
       or ends with an extension that is in ``PATHEXT``; and filenames that
       have no extension can now be found.
 
-   .. versionchanged:: 3.12.1
-      On Windows, if *mode* includes ``os.X_OK``, executables with an
-      extension in ``PATHEXT`` will be preferred over executables without a
-      matching extension.
-      This brings behavior closer to that of Python 3.11.
-
 .. exception:: Error
 
    This exception collects exceptions that are raised during a multi-file
diff --git a/Lib/shutil.py b/Lib/shutil.py
index 20ad1cb5684b25..2d2856912893bd 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -1534,21 +1534,21 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None):
     if sys.platform == "win32":
         # PATHEXT is necessary to check on Windows.
         pathext_source = os.getenv("PATHEXT") or _WIN_DEFAULT_PATHEXT
-        pathext = [ext for ext in pathext_source.split(os.pathsep) if ext]
+        pathext = pathext_source.split(os.pathsep)
+        pathext = [ext.rstrip('.') for ext in pathext if ext]
 
         if use_bytes:
             pathext = [os.fsencode(ext) for ext in pathext]
 
-        files = ([cmd] + [cmd + ext for ext in pathext])
+        files = [cmd + ext for ext in pathext]
 
-        # gh-109590. If we are looking for an executable, we need to look
-        # for a PATHEXT match. The first cmd is the direct match
-        # (e.g. python.exe instead of python)
-        # Check that direct match first if and only if the extension is in PATHEXT
-        # Otherwise check it last
-        suffix = os.path.splitext(files[0])[1].upper()
-        if mode & os.X_OK and not any(suffix == ext.upper() for ext in pathext):
-            files.append(files.pop(0))
+        # If X_OK in mode, simulate the cmd.exe behavior: look at direct
+        # match if and only if the extension is in PATHEXT.
+        # If X_OK not in mode, simulate the first result of where.exe:
+        # always look at direct match before a PATHEXT match.
+        normcmd = cmd.upper()
+        if not (mode & os.X_OK) or any(normcmd.endswith(ext.upper()) for ext in pathext):
+            files.insert(0, cmd)
     else:
         # On other platforms you don't have things like PATHEXT to tell you
         # what file suffixes are executable, so just pass on cmd as-is.
@@ -1557,7 +1557,7 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None):
     seen = set()
     for dir in path:
         normdir = os.path.normcase(dir)
-        if not normdir in seen:
+        if normdir not in seen:
             seen.add(normdir)
             for thefile in files:
                 name = os.path.join(dir, thefile)
diff --git a/Lib/test/test_shutil.py b/Lib/test/test_shutil.py
index 7bc5d12e09c057..c553ea09e07d55 100644
--- a/Lib/test/test_shutil.py
+++ b/Lib/test/test_shutil.py
@@ -71,18 +71,17 @@ def wrap(*args, **kwargs):
             os.rename = builtin_rename
     return wrap
 
-def write_file(path, content, binary=False):
+def create_file(path, content=b''):
     """Write *content* to a file located at *path*.
 
     If *path* is a tuple instead of a string, os.path.join will be used to
-    make a path.  If *binary* is true, the file will be opened in binary
-    mode.
+    make a path.
     """
     if isinstance(path, tuple):
         path = os.path.join(*path)
-    mode = 'wb' if binary else 'w'
-    encoding = None if binary else "utf-8"
-    with open(path, mode, encoding=encoding) as fp:
+    if isinstance(content, str):
+        content = content.encode()
+    with open(path, 'xb') as fp:
         fp.write(content)
 
 def write_test_file(path, size):
@@ -191,7 +190,7 @@ def test_rmtree_works_on_bytes(self):
         tmp = self.mkdtemp()
         victim = os.path.join(tmp, 'killme')
         os.mkdir(victim)
-        write_file(os.path.join(victim, 'somefile'), 'foo')
+        create_file(os.path.join(victim, 'somefile'), 'foo')
         victim = os.fsencode(victim)
         self.assertIsInstance(victim, bytes)
         shutil.rmtree(victim)
@@ -243,7 +242,7 @@ def test_rmtree_works_on_symlinks(self):
         for d in dir1, dir2, dir3:
             os.mkdir(d)
         file1 = os.path.join(tmp, 'file1')
-        write_file(file1, 'foo')
+        create_file(file1, 'foo')
         link1 = os.path.join(dir1, 'link1')
         os.symlink(dir2, link1)
         link2 = os.path.join(dir1, 'link2')
@@ -305,7 +304,7 @@ def test_rmtree_works_on_junctions(self):
         for d in dir1, dir2, dir3:
             os.mkdir(d)
         file1 = os.path.join(tmp, 'file1')
-        write_file(file1, 'foo')
+        create_file(file1, 'foo')
         link1 = os.path.join(dir1, 'link1')
         _winapi.CreateJunction(dir2, link1)
         link2 = os.path.join(dir1, 'link2')
@@ -327,8 +326,8 @@ def test_rmtree_errors_onerror(self):
 
         # existing file
         tmpdir = self.mkdtemp()
-        write_file((tmpdir, "tstfile"), "")
         filename = os.path.join(tmpdir, "tstfile")
+        create_file(filename)
         with self.assertRaises(NotADirectoryError) as cm:
             shutil.rmtree(filename)
         self.assertEqual(cm.exception.filename, filename)
@@ -359,8 +358,8 @@ def test_rmtree_errors_onexc(self):
 
         # existing file
         tmpdir = self.mkdtemp()
-        write_file((tmpdir, "tstfile"), "")
         filename = os.path.join(tmpdir, "tstfile")
+        create_file(filename)
         with self.assertRaises(NotADirectoryError) as cm:
             shutil.rmtree(filename)
         self.assertEqual(cm.exception.filename, filename)
@@ -549,7 +548,7 @@ def raiser(fn, *args, **kwargs):
             os.lstat = raiser
 
             os.mkdir(TESTFN)
-            write_file((TESTFN, 'foo'), 'foo')
+            create_file((TESTFN, 'foo'), 'foo')
             shutil.rmtree(TESTFN)
         finally:
             os.lstat = orig_lstat
@@ -622,7 +621,7 @@ def test_rmtree_with_dir_fd(self):
         self.addCleanup(os.close, dir_fd)
         os.mkdir(fullname)
         os.mkdir(os.path.join(fullname, 'subdir'))
-        write_file(os.path.join(fullname, 'subdir', 'somefile'), 'foo')
+        create_file(os.path.join(fullname, 'subdir', 'somefile'), 'foo')
         self.assertTrue(os.path.exists(fullname))
         shutil.rmtree(victim, dir_fd=dir_fd)
         self.assertFalse(os.path.exists(fullname))
@@ -662,7 +661,7 @@ def test_rmtree_on_junction(self):
             src = os.path.join(TESTFN, 'cheese')
             dst = os.path.join(TESTFN, 'shop')
             os.mkdir(src)
-            open(os.path.join(src, 'spam'), 'wb').close()
+            create_file(os.path.join(src, 'spam'))
             _winapi.CreateJunction(src, dst)
             self.assertRaises(OSError, shutil.rmtree, dst)
             shutil.rmtree(dst, ignore_errors=True)
@@ -704,9 +703,9 @@ def test_copytree_simple(self):
         dst_dir = os.path.join(self.mkdtemp(), 'destination')
         self.addCleanup(shutil.rmtree, src_dir)
         self.addCleanup(shutil.rmtree, os.path.dirname(dst_dir))
-        write_file((src_dir, 'test.txt'), '123')
+        create_file((src_dir, 'test.txt'), '123')
         os.mkdir(os.path.join(src_dir, 'test_dir'))
-        write_file((src_dir, 'test_dir', 'test.txt'), '456')
+        create_file((src_dir, 'test_dir', 'test.txt'), '456')
 
         shutil.copytree(src_dir, dst_dir)
         self.assertTrue(os.path.isfile(os.path.join(dst_dir, 'test.txt')))
@@ -724,11 +723,11 @@ def test_copytree_dirs_exist_ok(self):
         self.addCleanup(shutil.rmtree, src_dir)
         self.addCleanup(shutil.rmtree, dst_dir)
 
-        write_file((src_dir, 'nonexisting.txt'), '123')
+        create_file((src_dir, 'nonexisting.txt'), '123')
         os.mkdir(os.path.join(src_dir, 'existing_dir'))
         os.mkdir(os.path.join(dst_dir, 'existing_dir'))
-        write_file((dst_dir, 'existing_dir', 'existing.txt'), 'will be replaced')
-        write_file((src_dir, 'existing_dir', 'existing.txt'), 'has been replaced')
+        create_file((dst_dir, 'existing_dir', 'existing.txt'), 'will be replaced')
+        create_file((src_dir, 'existing_dir', 'existing.txt'), 'has been replaced')
 
         shutil.copytree(src_dir, dst_dir, dirs_exist_ok=True)
         self.assertTrue(os.path.isfile(os.path.join(dst_dir, 'nonexisting.txt')))
@@ -751,7 +750,7 @@ def test_copytree_symlinks(self):
         sub_dir = os.path.join(src_dir, 'sub')
         os.mkdir(src_dir)
         os.mkdir(sub_dir)
-        write_file((src_dir, 'file.txt'), 'foo')
+        create_file((src_dir, 'file.txt'), 'foo')
         src_link = os.path.join(sub_dir, 'link')
         dst_link = os.path.join(dst_dir, 'sub/link')
         os.symlink(os.path.join(src_dir, 'file.txt'),
@@ -782,16 +781,16 @@ def test_copytree_with_exclude(self):
         src_dir = self.mkdtemp()
         try:
             dst_dir = join(self.mkdtemp(), 'destination')
-            write_file((src_dir, 'test.txt'), '123')
-            write_file((src_dir, 'test.tmp'), '123')
+            create_file((src_dir, 'test.txt'), '123')
+            create_file((src_dir, 'test.tmp'), '123')
             os.mkdir(join(src_dir, 'test_dir'))
-            write_file((src_dir, 'test_dir', 'test.txt'), '456')
+            create_file((src_dir, 'test_dir', 'test.txt'), '456')
             os.mkdir(join(src_dir, 'test_dir2'))
-            write_file((src_dir, 'test_dir2', 'test.txt'), '456')
+            create_file((src_dir, 'test_dir2', 'test.txt'), '456')
             os.mkdir(join(src_dir, 'test_dir2', 'subdir'))
             os.mkdir(join(src_dir, 'test_dir2', 'subdir2'))
-            write_file((src_dir, 'test_dir2', 'subdir', 'test.txt'), '456')
-            write_file((src_dir, 'test_dir2', 'subdir2', 'test.py'), '456')
+            create_file((src_dir, 'test_dir2', 'subdir', 'test.txt'), '456')
+            create_file((src_dir, 'test_dir2', 'subdir2', 'test.py'), '456')
 
             # testing glob-like patterns
             try:
@@ -850,7 +849,7 @@ def test_copytree_arg_types_of_ignore(self):
         os.mkdir(join(src_dir))
         os.mkdir(join(src_dir, 'test_dir'))
         os.mkdir(os.path.join(src_dir, 'test_dir', 'subdir'))
-        write_file((src_dir, 'test_dir', 'subdir', 'test.txt'), '456')
+        create_file((src_dir, 'test_dir', 'subdir', 'test.txt'), '456')
 
         invokations = []
 
@@ -890,9 +889,9 @@ def test_copytree_retains_permissions(self):
         self.addCleanup(shutil.rmtree, tmp_dir)
 
         os.chmod(src_dir, 0o777)
-        write_file((src_dir, 'permissive.txt'), '123')
+        create_file((src_dir, 'permissive.txt'), '123')
         os.chmod(os.path.join(src_dir, 'permissive.txt'), 0o777)
-        write_file((src_dir, 'restrictive.txt'), '456')
+        create_file((src_dir, 'restrictive.txt'), '456')
         os.chmod(os.path.join(src_dir, 'restrictive.txt'), 0o600)
         restrictive_subdir = tempfile.mkdtemp(dir=src_dir)
         self.addCleanup(os_helper.rmtree, restrictive_subdir)
@@ -935,8 +934,7 @@ def custom_cpfun(a, b):
         flag = []
         src = self.mkdtemp()
         dst = tempfile.mktemp(dir=self.mkdtemp())
-        with open(os.path.join(src, 'foo'), 'w', encoding='utf-8') as f:
-            f.close()
+        create_file(os.path.join(src, 'foo'))
         shutil.copytree(src, dst, copy_function=custom_cpfun)
         self.assertEqual(len(flag), 1)
 
@@ -971,9 +969,9 @@ def test_copytree_named_pipe(self):
     def test_copytree_special_func(self):
         src_dir = self.mkdtemp()
         dst_dir = os.path.join(self.mkdtemp(), 'destination')
-        write_file((src_dir, 'test.txt'), '123')
+        create_file((src_dir, 'test.txt'), '123')
         os.mkdir(os.path.join(src_dir, 'test_dir'))
-        write_file((src_dir, 'test_dir', 'test.txt'), '456')
+        create_file((src_dir, 'test_dir', 'test.txt'), '456')
 
         copied = []
         def _copy(src, dst):
@@ -986,7 +984,7 @@ def _copy(src, dst):
     def test_copytree_dangling_symlinks(self):
         src_dir = self.mkdtemp()
         valid_file = os.path.join(src_dir, 'test.txt')
-        write_file(valid_file, 'abc')
+        create_file(valid_file, 'abc')
         dir_a = os.path.join(src_dir, 'dir_a')
         os.mkdir(dir_a)
         for d in src_dir, dir_a:
@@ -1014,8 +1012,7 @@ def test_copytree_symlink_dir(self):
         src_dir = self.mkdtemp()
         dst_dir = os.path.join(self.mkdtemp(), 'destination')
         os.mkdir(os.path.join(src_dir, 'real_dir'))
-        with open(os.path.join(src_dir, 'real_dir', 'test.txt'), 'wb'):
-            pass
+        create_file(os.path.join(src_dir, 'real_dir', 'test.txt'))
         os.symlink(os.path.join(src_dir, 'real_dir'),
                    os.path.join(src_dir, 'link_to_dir'),
                    target_is_directory=True)
@@ -1035,7 +1032,7 @@ def test_copytree_return_value(self):
         dst_dir = src_dir + "dest"
         self.addCleanup(shutil.rmtree, dst_dir, True)
         src = os.path.join(src_dir, 'foo')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         rv = shutil.copytree(src_dir, dst_dir)
         self.assertEqual(['foo'], os.listdir(rv))
 
@@ -1047,7 +1044,7 @@ def test_copytree_subdirectory(self):
         dst_dir = os.path.join(src_dir, "somevendor", "1.0")
         os.makedirs(src_dir)
         src = os.path.join(src_dir, 'pol')
-        write_file(src, 'pol')
+        create_file(src, 'pol')
         rv = shutil.copytree(src_dir, dst_dir)
         self.assertEqual(['pol'], os.listdir(rv))
 
@@ -1062,8 +1059,8 @@ def test_copymode_follow_symlinks(self):
         dst = os.path.join(tmp_dir, 'bar')
         src_link = os.path.join(tmp_dir, 'baz')
         dst_link = os.path.join(tmp_dir, 'quux')
-        write_file(src, 'foo')
-        write_file(dst, 'foo')
+        create_file(src, 'foo')
+        create_file(dst, 'foo')
         os.symlink(src, src_link)
         os.symlink(dst, dst_link)
         os.chmod(src, stat.S_IRWXU|stat.S_IRWXG)
@@ -1095,8 +1092,8 @@ def test_copymode_symlink_to_symlink(self):
         dst = os.path.join(tmp_dir, 'bar')
         src_link = os.path.join(tmp_dir, 'baz')
         dst_link = os.path.join(tmp_dir, 'quux')
-        write_file(src, 'foo')
-        write_file(dst, 'foo')
+        create_file(src, 'foo')
+        create_file(dst, 'foo')
         os.symlink(src, src_link)
         os.symlink(dst, dst_link)
         os.chmod(src, stat.S_IRWXU|stat.S_IRWXG)
@@ -1126,8 +1123,8 @@ def test_copymode_symlink_to_symlink_wo_lchmod(self):
         dst = os.path.join(tmp_dir, 'bar')
         src_link = os.path.join(tmp_dir, 'baz')
         dst_link = os.path.join(tmp_dir, 'quux')
-        write_file(src, 'foo')
-        write_file(dst, 'foo')
+        create_file(src, 'foo')
+        create_file(dst, 'foo')
         os.symlink(src, src_link)
         os.symlink(dst, dst_link)
         shutil.copymode(src_link, dst_link, follow_symlinks=False)  # silent fail
@@ -1141,11 +1138,11 @@ def test_copystat_symlinks(self):
         dst = os.path.join(tmp_dir, 'bar')
         src_link = os.path.join(tmp_dir, 'baz')
         dst_link = os.path.join(tmp_dir, 'qux')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         src_stat = os.stat(src)
         os.utime(src, (src_stat.st_atime,
                        src_stat.st_mtime - 42.0))  # ensure different mtimes
-        write_file(dst, 'bar')
+        create_file(dst, 'bar')
         self.assertNotEqual(os.stat(src).st_mtime, os.stat(dst).st_mtime)
         os.symlink(src, src_link)
         os.symlink(dst, dst_link)
@@ -1185,8 +1182,8 @@ def test_copystat_handles_harmless_chflags_errors(self):
         tmpdir = self.mkdtemp()
         file1 = os.path.join(tmpdir, 'file1')
         file2 = os.path.join(tmpdir, 'file2')
-        write_file(file1, 'xxx')
-        write_file(file2, 'xxx')
+        create_file(file1, 'xxx')
+        create_file(file2, 'xxx')
 
         def make_chflags_raiser(err):
             ex = OSError()
@@ -1212,9 +1209,9 @@ def _chflags_raiser(path, flags, *, follow_symlinks=True):
     def test_copyxattr(self):
         tmp_dir = self.mkdtemp()
         src = os.path.join(tmp_dir, 'foo')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         dst = os.path.join(tmp_dir, 'bar')
-        write_file(dst, 'bar')
+        create_file(dst, 'bar')
 
         # no xattr == no problem
         shutil._copyxattr(src, dst)
@@ -1228,7 +1225,7 @@ def test_copyxattr(self):
                 os.getxattr(dst, 'user.foo'))
         # check errors don't affect other attrs
         os.remove(dst)
-        write_file(dst, 'bar')
+        create_file(dst, 'bar')
         os_error = OSError(errno.EPERM, 'EPERM')
 
         def _raise_on_user_foo(fname, attr, val, **kwargs):
@@ -1258,15 +1255,15 @@ def _raise_on_src(fname, *, follow_symlinks=True):
         # test that shutil.copystat copies xattrs
         src = os.path.join(tmp_dir, 'the_original')
         srcro = os.path.join(tmp_dir, 'the_original_ro')
-        write_file(src, src)
-        write_file(srcro, srcro)
+        create_file(src, src)
+        create_file(srcro, srcro)
         os.setxattr(src, 'user.the_value', b'fiddly')
         os.setxattr(srcro, 'user.the_value', b'fiddly')
         os.chmod(srcro, 0o444)
         dst = os.path.join(tmp_dir, 'the_copy')
         dstro = os.path.join(tmp_dir, 'the_copy_ro')
-        write_file(dst, dst)
-        write_file(dstro, dstro)
+        create_file(dst, dst)
+        create_file(dstro, dstro)
         shutil.copystat(src, dst)
         shutil.copystat(srcro, dstro)
         self.assertEqual(os.getxattr(dst, 'user.the_value'), b'fiddly')
@@ -1282,13 +1279,13 @@ def test_copyxattr_symlinks(self):
         tmp_dir = self.mkdtemp()
         src = os.path.join(tmp_dir, 'foo')
         src_link = os.path.join(tmp_dir, 'baz')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         os.symlink(src, src_link)
         os.setxattr(src, 'trusted.foo', b'42')
         os.setxattr(src_link, 'trusted.foo', b'43', follow_symlinks=False)
         dst = os.path.join(tmp_dir, 'bar')
         dst_link = os.path.join(tmp_dir, 'qux')
-        write_file(dst, 'bar')
+        create_file(dst, 'bar')
         os.symlink(dst, dst_link)
         shutil._copyxattr(src_link, dst_link, follow_symlinks=False)
         self.assertEqual(os.getxattr(dst_link, 'trusted.foo', follow_symlinks=False), b'43')
@@ -1301,7 +1298,7 @@ def test_copyxattr_symlinks(self):
     def _copy_file(self, method):
         fname = 'test.txt'
         tmpdir = self.mkdtemp()
-        write_file((tmpdir, fname), 'xxx')
+        create_file((tmpdir, fname), 'xxx')
         file1 = os.path.join(tmpdir, fname)
         tmpdir2 = self.mkdtemp()
         method(file1, tmpdir2)
@@ -1320,7 +1317,7 @@ def test_copy_symlinks(self):
         src = os.path.join(tmp_dir, 'foo')
         dst = os.path.join(tmp_dir, 'bar')
         src_link = os.path.join(tmp_dir, 'baz')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         os.symlink(src, src_link)
         if hasattr(os, 'lchmod'):
             os.lchmod(src_link, stat.S_IRWXU | stat.S_IRWXO)
@@ -1362,7 +1359,7 @@ def test_copy2_symlinks(self):
         src = os.path.join(tmp_dir, 'foo')
         dst = os.path.join(tmp_dir, 'bar')
         src_link = os.path.join(tmp_dir, 'baz')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         os.symlink(src, src_link)
         if hasattr(os, 'lchmod'):
             os.lchmod(src_link, stat.S_IRWXU | stat.S_IRWXO)
@@ -1396,7 +1393,7 @@ def test_copy2_xattr(self):
         tmp_dir = self.mkdtemp()
         src = os.path.join(tmp_dir, 'foo')
         dst = os.path.join(tmp_dir, 'bar')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         os.setxattr(src, 'user.foo', b'42')
         shutil.copy2(src, dst)
         self.assertEqual(
@@ -1410,7 +1407,7 @@ def test_copy_return_value(self):
             src_dir = self.mkdtemp()
             dst_dir = self.mkdtemp()
             src = os.path.join(src_dir, 'foo')
-            write_file(src, 'foo')
+            create_file(src, 'foo')
             rv = fn(src, dst_dir)
             self.assertEqual(rv, os.path.join(dst_dir, 'foo'))
             rv = fn(src, os.path.join(dst_dir, 'bar'))
@@ -1427,7 +1424,7 @@ def _test_copy_dir(self, copy_func):
         src_file = os.path.join(src_dir, 'foo')
         dir2 = self.mkdtemp()
         dst = os.path.join(src_dir, 'does_not_exist/')
-        write_file(src_file, 'foo')
+        create_file(src_file, 'foo')
         if sys.platform == "win32":
             err = PermissionError
         else:
@@ -1447,7 +1444,7 @@ def test_copyfile_symlinks(self):
         dst = os.path.join(tmp_dir, 'dst')
         dst_link = os.path.join(tmp_dir, 'dst_link')
         link = os.path.join(tmp_dir, 'link')
-        write_file(src, 'foo')
+        create_file(src, 'foo')
         os.symlink(src, link)
         # don't follow
         shutil.copyfile(link, dst_link, follow_symlinks=False)
@@ -1464,8 +1461,7 @@ def test_dont_copy_file_onto_link_to_itself(self):
         src = os.path.join(TESTFN, 'cheese')
         dst = os.path.join(TESTFN, 'shop')
         try:
-            with open(src, 'w', encoding='utf-8') as f:
-                f.write('cheddar')
+            create_file(src, 'cheddar')
             try:
                 os.link(src, dst)
             except PermissionError as e:
@@ -1484,8 +1480,7 @@ def test_dont_copy_file_onto_symlink_to_itself(self):
         src = os.path.join(TESTFN, 'cheese')
         dst = os.path.join(TESTFN, 'shop')
         try:
-            with open(src, 'w', encoding='utf-8') as f:
-                f.write('cheddar')
+            create_file(src, 'cheddar')
             # Using `src` here would mean we end up with a symlink pointing
             # to TESTFN/TESTFN/cheese, while it should point at
             # TESTFN/cheese.
@@ -1520,7 +1515,7 @@ def test_copyfile_return_value(self):
         dst_dir = self.mkdtemp()
         dst_file = os.path.join(dst_dir, 'bar')
         src_file = os.path.join(src_dir, 'foo')
-        write_file(src_file, 'foo')
+        create_file(src_file, 'foo')
         rv = shutil.copyfile(src_file, dst_file)
         self.assertTrue(os.path.exists(rv))
         self.assertEqual(read_file(src_file), read_file(dst_file))
@@ -1530,7 +1525,7 @@ def test_copyfile_same_file(self):
         # are the same.
         src_dir = self.mkdtemp()
         src_file = os.path.join(src_dir, 'foo')
-        write_file(src_file, 'foo')
+        create_file(src_file, 'foo')
         self.assertRaises(SameFileError, shutil.copyfile, src_file, src_file)
         # But Error should work too, to stay backward compatible.
         self.assertRaises(Error, shutil.copyfile, src_file, src_file)
@@ -1547,7 +1542,7 @@ def test_copyfile_nonexistent_dir(self):
         src_dir = self.mkdtemp()
         src_file = os.path.join(src_dir, 'foo')
         dst = os.path.join(src_dir, 'does_not_exist/')
-        write_file(src_file, 'foo')
+        create_file(src_file, 'foo')
         self.assertRaises(FileNotFoundError, shutil.copyfile, src_file, dst)
 
     def test_copyfile_copy_dir(self):
@@ -1558,7 +1553,7 @@ def test_copyfile_copy_dir(self):
         src_file = os.path.join(src_dir, 'foo')
         dir2 = self.mkdtemp()
         dst = os.path.join(src_dir, 'does_not_exist/')
-        write_file(src_file, 'foo')
+        create_file(src_file, 'foo')
         if sys.platform == "win32":
             err = PermissionError
         else:
@@ -1584,13 +1579,13 @@ def _create_files(self, base_dir='dist'):
         root_dir = self.mkdtemp()
         dist = os.path.join(root_dir, base_dir)
         os.makedirs(dist, exist_ok=True)
-        write_file((dist, 'file1'), 'xxx')
-        write_file((dist, 'file2'), 'xxx')
+        create_file((dist, 'file1'), 'xxx')
+        create_file((dist, 'file2'), 'xxx')
         os.mkdir(os.path.join(dist, 'sub'))
-        write_file((dist, 'sub', 'file3'), 'xxx')
+        create_file((dist, 'sub', 'file3'), 'xxx')
         os.mkdir(os.path.join(dist, 'sub2'))
         if base_dir:
-            write_file((root_dir, 'outer'), 'xxx')
+            create_file((root_dir, 'outer'), 'xxx')
         return root_dir, base_dir
 
     @support.requires_zlib()
@@ -2170,7 +2165,7 @@ def test_disk_usage(self):
     def test_chown(self):
         dirname = self.mkdtemp()
         filename = tempfile.mktemp(dir=dirname)
-        write_file(filename, 'testing chown function')
+        create_file(filename, 'testing chown function')
 
         with self.assertRaises(ValueError):
             shutil.chown(filename)
@@ -2231,37 +2226,41 @@ def check_chown(path, uid=None, gid=None):
 class TestWhich(BaseTest, unittest.TestCase):
 
     def setUp(self):
-        self.temp_dir = self.mkdtemp(prefix="Tmp")
+        temp_dir = self.mkdtemp(prefix="Tmp")
+        base_dir = os.path.join(temp_dir, TESTFN + '-basedir')
+        os.mkdir(base_dir)
+        self.dir = os.path.join(base_dir, TESTFN + '-dir')
+        os.mkdir(self.dir)
+        self.other_dir = os.path.join(base_dir, TESTFN + '-dir2')
+        os.mkdir(self.other_dir)
         # Give the temp_file an ".exe" suffix for all.
         # It's needed on Windows and not harmful on other platforms.
-        self.temp_file = tempfile.NamedTemporaryFile(dir=self.temp_dir,
-                                                     prefix="Tmp",
-                                                     suffix=".Exe")
-        os.chmod(self.temp_file.name, stat.S_IXUSR)
-        self.addCleanup(self.temp_file.close)
-        self.dir, self.file = os.path.split(self.temp_file.name)
+        self.file = TESTFN + '.Exe'
+        self.filepath = os.path.join(self.dir, self.file)
+        self.create_file(self.filepath)
         self.env_path = self.dir
         self.curdir = os.curdir
         self.ext = ".EXE"
 
-    def to_text_type(self, s):
-        '''
-        In this class we're testing with str, so convert s to a str
-        '''
-        if isinstance(s, bytes):
-            return s.decode()
-        return s
+    to_text_type = staticmethod(os.fsdecode)
+
+    def create_file(self, path):
+        create_file(path)
+        os.chmod(path, 0o755)
+
+    def assertNormEqual(self, actual, expected):
+        self.assertEqual(os.path.normcase(actual), os.path.normcase(expected))
 
     def test_basic(self):
         # Given an EXE in a directory, it should be returned.
         rv = shutil.which(self.file, path=self.dir)
-        self.assertEqual(rv, self.temp_file.name)
+        self.assertEqual(rv, self.filepath)
 
     def test_absolute_cmd(self):
         # When given the fully qualified path to an executable that exists,
         # it should be returned.
-        rv = shutil.which(self.temp_file.name, path=self.temp_dir)
-        self.assertEqual(rv, self.temp_file.name)
+        rv = shutil.which(self.filepath, path=self.other_dir)
+        self.assertEqual(rv, self.filepath)
 
     def test_relative_cmd(self):
         # When given the relative path with a directory part to an executable
@@ -2269,7 +2268,7 @@ def test_relative_cmd(self):
         base_dir, tail_dir = os.path.split(self.dir)
         relpath = os.path.join(tail_dir, self.file)
         with os_helper.change_cwd(path=base_dir):
-            rv = shutil.which(relpath, path=self.temp_dir)
+            rv = shutil.which(relpath, path=self.other_dir)
             self.assertEqual(rv, relpath)
         # But it shouldn't be searched in PATH directories (issue #16957).
         with os_helper.change_cwd(path=self.dir):
@@ -2280,9 +2279,8 @@ def test_relative_cmd(self):
                          "test is for non win32")
     def test_cwd_non_win32(self):
         # Issue #16957
-        base_dir = os.path.dirname(self.dir)
         with os_helper.change_cwd(path=self.dir):
-            rv = shutil.which(self.file, path=base_dir)
+            rv = shutil.which(self.file, path=self.other_dir)
             # non-win32: shouldn't match in the current directory.
             self.assertIsNone(rv)
 
@@ -2292,57 +2290,32 @@ def test_cwd_win32(self):
         base_dir = os.path.dirname(self.dir)
         with os_helper.change_cwd(path=self.dir):
             with unittest.mock.patch('shutil._win_path_needs_curdir', return_value=True):
-                rv = shutil.which(self.file, path=base_dir)
+                rv = shutil.which(self.file, path=self.other_dir)
                 # Current directory implicitly on PATH
                 self.assertEqual(rv, os.path.join(self.curdir, self.file))
             with unittest.mock.patch('shutil._win_path_needs_curdir', return_value=False):
-                rv = shutil.which(self.file, path=base_dir)
+                rv = shutil.which(self.file, path=self.other_dir)
                 # Current directory not on PATH
                 self.assertIsNone(rv)
 
     @unittest.skipUnless(sys.platform == "win32",
                          "test is for win32")
     def test_cwd_win32_added_before_all_other_path(self):
-        base_dir = pathlib.Path(os.fsdecode(self.dir))
-
-        elsewhere_in_path_dir = base_dir / 'dir1'
-        elsewhere_in_path_dir.mkdir()
-        match_elsewhere_in_path = elsewhere_in_path_dir / 'hello.exe'
-        match_elsewhere_in_path.touch()
-
-        exe_in_cwd = base_dir / 'hello.exe'
-        exe_in_cwd.touch()
-
-        with os_helper.change_cwd(path=base_dir):
-            with unittest.mock.patch('shutil._win_path_needs_curdir', return_value=True):
-                rv = shutil.which('hello.exe', path=elsewhere_in_path_dir)
-
-            self.assertEqual(os.path.abspath(rv), os.path.abspath(exe_in_cwd))
-
-    @unittest.skipUnless(sys.platform == "win32",
-                         "test is for win32")
-    def test_pathext_match_before_path_full_match(self):
-        base_dir = pathlib.Path(os.fsdecode(self.dir))
-        dir1 = base_dir / 'dir1'
-        dir2 = base_dir / 'dir2'
-        dir1.mkdir()
-        dir2.mkdir()
-
-        pathext_match = dir1 / 'hello.com.exe'
-        path_match = dir2 / 'hello.com'
-        pathext_match.touch()
-        path_match.touch()
-
-        test_path = os.pathsep.join([str(dir1), str(dir2)])
-        assert os.path.basename(shutil.which(
-            'hello.com', path=test_path, mode = os.F_OK
-        )).lower() == 'hello.com.exe'
+        other_file_path = os.path.join(self.other_dir, self.file)
+        self.create_file(other_file_path)
+        with unittest.mock.patch('shutil._win_path_needs_curdir', return_value=True):
+            with os_helper.change_cwd(path=self.dir):
+                rv = shutil.which(self.file, path=self.other_dir)
+                self.assertEqual(rv, os.path.join(self.curdir, self.file))
+            with os_helper.change_cwd(path=self.other_dir):
+                rv = shutil.which(self.file, path=self.dir)
+                self.assertEqual(rv, os.path.join(self.curdir, self.file))
 
     @os_helper.skip_if_dac_override
     def test_non_matching_mode(self):
         # Set the file read-only and ask for writeable files.
-        os.chmod(self.temp_file.name, stat.S_IREAD)
-        if os.access(self.temp_file.name, os.W_OK):
+        os.chmod(self.filepath, stat.S_IREAD)
+        if os.access(self.filepath, os.W_OK):
             self.skipTest("can't set the file read-only")
         rv = shutil.which(self.file, path=self.dir, mode=os.W_OK)
         self.assertIsNone(rv)
@@ -2364,13 +2337,13 @@ def test_pathext_checking(self):
         # Ask for the file without the ".exe" extension, then ensure that
         # it gets found properly with the extension.
         rv = shutil.which(self.file[:-4], path=self.dir)
-        self.assertEqual(rv, self.temp_file.name[:-4] + self.ext)
+        self.assertEqual(rv, self.filepath[:-4] + self.ext)
 
     def test_environ_path(self):
         with os_helper.EnvironmentVarGuard() as env:
             env['PATH'] = self.env_path
             rv = shutil.which(self.file)
-            self.assertEqual(rv, self.temp_file.name)
+            self.assertEqual(rv, self.filepath)
 
     def test_environ_path_empty(self):
         # PATH='': no match
@@ -2384,12 +2357,9 @@ def test_environ_path_empty(self):
                 self.assertIsNone(rv)
 
     def test_environ_path_cwd(self):
-        expected_cwd = os.path.basename(self.temp_file.name)
+        expected_cwd = self.file
         if sys.platform == "win32":
-            curdir = os.curdir
-            if isinstance(expected_cwd, bytes):
-                curdir = os.fsencode(curdir)
-            expected_cwd = os.path.join(curdir, expected_cwd)
+            expected_cwd = os.path.join(self.curdir, expected_cwd)
 
         # PATH=':': explicitly looks in the current directory
         with os_helper.EnvironmentVarGuard() as env:
@@ -2414,14 +2384,14 @@ def test_environ_path_missing(self):
                                      create=True), \
                  support.swap_attr(os, 'defpath', self.dir):
                 rv = shutil.which(self.file)
-            self.assertEqual(rv, self.temp_file.name)
+            self.assertEqual(rv, self.filepath)
 
             # with confstr
             with unittest.mock.patch('os.confstr', return_value=self.dir, \
                                      create=True), \
                  support.swap_attr(os, 'defpath', ''):
                 rv = shutil.which(self.file)
-            self.assertEqual(rv, self.temp_file.name)
+            self.assertEqual(rv, self.filepath)
 
     def test_empty_path(self):
         base_dir = os.path.dirname(self.dir)
@@ -2439,50 +2409,88 @@ def test_empty_path_no_PATH(self):
 
     @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
     def test_pathext(self):
-        ext = self.to_text_type(".xyz")
-        temp_filexyz = tempfile.NamedTemporaryFile(dir=self.temp_dir,
-                                                   prefix=self.to_text_type("Tmp2"), suffix=ext)
-        os.chmod(temp_filexyz.name, stat.S_IXUSR)
-        self.addCleanup(temp_filexyz.close)
-
-        # strip path and extension
-        program = os.path.basename(temp_filexyz.name)
-        program = os.path.splitext(program)[0]
-
+        ext = '.xyz'
+        cmd = self.to_text_type(TESTFN2)
+        cmdext = cmd + self.to_text_type(ext)
+        filepath = os.path.join(self.dir, cmdext)
+        self.create_file(filepath)
         with os_helper.EnvironmentVarGuard() as env:
-            env['PATHEXT'] = ext if isinstance(ext, str) else ext.decode()
-            rv = shutil.which(program, path=self.temp_dir)
-            self.assertEqual(rv, temp_filexyz.name)
+            env['PATHEXT'] = ext
+            self.assertEqual(shutil.which(cmd, path=self.dir), filepath)
+            self.assertEqual(shutil.which(cmdext, path=self.dir), filepath)
 
     # Issue 40592: See https://bugs.python.org/issue40592
     @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
     def test_pathext_with_empty_str(self):
-        ext = self.to_text_type(".xyz")
-        temp_filexyz = tempfile.NamedTemporaryFile(dir=self.temp_dir,
-                                                   prefix=self.to_text_type("Tmp2"), suffix=ext)
-        self.addCleanup(temp_filexyz.close)
+        ext = '.xyz'
+        cmd = self.to_text_type(TESTFN2)
+        cmdext = cmd + self.to_text_type(ext)
+        filepath = os.path.join(self.dir, cmdext)
+        self.create_file(filepath)
+        with os_helper.EnvironmentVarGuard() as env:
+            env['PATHEXT'] = ext + ';'  # note the ;
+            self.assertEqual(shutil.which(cmd, path=self.dir), filepath)
+            self.assertEqual(shutil.which(cmdext, path=self.dir), filepath)
 
-        # strip path and extension
-        program = os.path.basename(temp_filexyz.name)
-        program = os.path.splitext(program)[0]
+    @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
+    def test_pathext_with_multidot_extension(self):
+        ext = '.foo.bar'
+        cmd = self.to_text_type(TESTFN2)
+        cmdext = cmd + self.to_text_type(ext)
+        filepath = os.path.join(self.dir, cmdext)
+        self.create_file(filepath)
+        with os_helper.EnvironmentVarGuard() as env:
+            env['PATHEXT'] = ext
+            self.assertEqual(shutil.which(cmd, path=self.dir), filepath)
+            self.assertEqual(shutil.which(cmdext, path=self.dir), filepath)
 
+    @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
+    def test_pathext_with_null_extension(self):
+        cmd = self.to_text_type(TESTFN2)
+        cmddot = cmd + self.to_text_type('.')
+        filepath = os.path.join(self.dir, cmd)
+        self.create_file(filepath)
         with os_helper.EnvironmentVarGuard() as env:
-            env['PATHEXT'] = f"{ext if isinstance(ext, str) else ext.decode()};"  # note the ;
-            rv = shutil.which(program, path=self.temp_dir)
-            self.assertEqual(rv, temp_filexyz.name)
+            env['PATHEXT'] = '.xyz'
+            self.assertIsNone(shutil.which(cmd, path=self.dir))
+            self.assertIsNone(shutil.which(cmddot, path=self.dir))
+            env['PATHEXT'] = '.xyz;.'  # note the .
+            self.assertEqual(shutil.which(cmd, path=self.dir), filepath)
+            self.assertEqual(shutil.which(cmddot, path=self.dir),
+                             filepath + self.to_text_type('.'))
+            env['PATHEXT'] = '.xyz;..'  # multiple dots
+            self.assertEqual(shutil.which(cmd, path=self.dir), filepath)
+            self.assertEqual(shutil.which(cmddot, path=self.dir),
+                             filepath + self.to_text_type('.'))
+
+    @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
+    def test_pathext_extension_ends_with_dot(self):
+        ext = '.xyz'
+        cmd = self.to_text_type(TESTFN2)
+        cmdext = cmd + self.to_text_type(ext)
+        dot = self.to_text_type('.')
+        filepath = os.path.join(self.dir, cmdext)
+        self.create_file(filepath)
+        with os_helper.EnvironmentVarGuard() as env:
+            env['PATHEXT'] = ext + '.'
+            self.assertEqual(shutil.which(cmd, path=self.dir), filepath)  # cmd.exe hangs here
+            self.assertEqual(shutil.which(cmdext, path=self.dir), filepath)
+            self.assertIsNone(shutil.which(cmd + dot, path=self.dir))
+            self.assertIsNone(shutil.which(cmdext + dot, path=self.dir))
 
     # See GH-75586
     @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
     def test_pathext_applied_on_files_in_path(self):
+        ext = '.xyz'
+        cmd = self.to_text_type(TESTFN2)
+        cmdext = cmd + self.to_text_type(ext)
+        filepath = os.path.join(self.dir, cmdext)
+        self.create_file(filepath)
         with os_helper.EnvironmentVarGuard() as env:
-            env["PATH"] = self.temp_dir if isinstance(self.temp_dir, str) else self.temp_dir.decode()
-            env["PATHEXT"] = ".test"
-
-            test_path = os.path.join(self.temp_dir, self.to_text_type("test_program.test"))
-            open(test_path, 'w').close()
-            os.chmod(test_path, 0o755)
-
-            self.assertEqual(shutil.which(self.to_text_type("test_program")), test_path)
+            env["PATH"] = os.fsdecode(self.dir)
+            env["PATHEXT"] = ext
+            self.assertEqual(shutil.which(cmd), filepath)
+            self.assertEqual(shutil.which(cmdext), filepath)
 
     # See GH-75586
     @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
@@ -2498,49 +2506,107 @@ def test_win_path_needs_curdir(self):
             self.assertFalse(shutil._win_path_needs_curdir('dontcare', os.X_OK))
             need_curdir_mock.assert_called_once_with('dontcare')
 
-    # See GH-109590
     @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
-    def test_pathext_preferred_for_execute(self):
-        with os_helper.EnvironmentVarGuard() as env:
-            env["PATH"] = self.temp_dir if isinstance(self.temp_dir, str) else self.temp_dir.decode()
-            env["PATHEXT"] = ".test"
-
-            exe = os.path.join(self.temp_dir, self.to_text_type("test.exe"))
-            open(exe, 'w').close()
-            os.chmod(exe, 0o755)
+    def test_same_dir_with_pathext_extension(self):
+        cmd = self.file  # with .exe extension
+        # full match
+        self.assertNormEqual(shutil.which(cmd, path=self.dir), self.filepath)
+        self.assertNormEqual(shutil.which(cmd, path=self.dir, mode=os.F_OK),
+                             self.filepath)
+
+        cmd2 = cmd + self.to_text_type('.com')  # with .exe.com extension
+        other_file_path = os.path.join(self.dir, cmd2)
+        self.create_file(other_file_path)
+
+        # full match
+        self.assertNormEqual(shutil.which(cmd, path=self.dir), self.filepath)
+        self.assertNormEqual(shutil.which(cmd, path=self.dir, mode=os.F_OK),
+                             self.filepath)
+        self.assertNormEqual(shutil.which(cmd2, path=self.dir), other_file_path)
+        self.assertNormEqual(shutil.which(cmd2, path=self.dir, mode=os.F_OK),
+                             other_file_path)
 
-            # default behavior allows a direct match if nothing in PATHEXT matches
-            self.assertEqual(shutil.which(self.to_text_type("test.exe")), exe)
-
-            dot_test = os.path.join(self.temp_dir, self.to_text_type("test.exe.test"))
-            open(dot_test, 'w').close()
-            os.chmod(dot_test, 0o755)
-
-            # now we have a PATHEXT match, so it take precedence
-            self.assertEqual(shutil.which(self.to_text_type("test.exe")), dot_test)
-
-            # but if we don't use os.X_OK we don't change the order based off PATHEXT
-            # and therefore get the direct match.
-            self.assertEqual(shutil.which(self.to_text_type("test.exe"), mode=os.F_OK), exe)
-
-    # See GH-109590
     @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
-    def test_pathext_given_extension_preferred(self):
-        with os_helper.EnvironmentVarGuard() as env:
-            env["PATH"] = self.temp_dir if isinstance(self.temp_dir, str) else self.temp_dir.decode()
-            env["PATHEXT"] = ".exe2;.exe"
+    def test_same_dir_without_pathext_extension(self):
+        cmd = self.file[:-4]  # without .exe extension
+        # pathext match
+        self.assertNormEqual(shutil.which(cmd, path=self.dir), self.filepath)
+        self.assertNormEqual(shutil.which(cmd, path=self.dir, mode=os.F_OK),
+                             self.filepath)
+
+        # without extension
+        other_file_path = os.path.join(self.dir, cmd)
+        self.create_file(other_file_path)
+
+        # pathext match if mode contains X_OK
+        self.assertNormEqual(shutil.which(cmd, path=self.dir), self.filepath)
+        # full match
+        self.assertNormEqual(shutil.which(cmd, path=self.dir, mode=os.F_OK),
+                             other_file_path)
+        self.assertNormEqual(shutil.which(self.file, path=self.dir), self.filepath)
+        self.assertNormEqual(shutil.which(self.file, path=self.dir, mode=os.F_OK),
+                             self.filepath)
 
-            exe = os.path.join(self.temp_dir, self.to_text_type("test.exe"))
-            open(exe, 'w').close()
-            os.chmod(exe, 0o755)
-
-            exe2 = os.path.join(self.temp_dir, self.to_text_type("test.exe2"))
-            open(exe2, 'w').close()
-            os.chmod(exe2, 0o755)
+    @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
+    def test_dir_order_with_pathext_extension(self):
+        cmd = self.file  # with .exe extension
+        search_path = os.pathsep.join([os.fsdecode(self.other_dir),
+                                       os.fsdecode(self.dir)])
+        # full match in the second directory
+        self.assertNormEqual(shutil.which(cmd, path=search_path), self.filepath)
+        self.assertNormEqual(shutil.which(cmd, path=search_path, mode=os.F_OK),
+                             self.filepath)
+
+        cmd2 = cmd + self.to_text_type('.com')  # with .exe.com extension
+        other_file_path = os.path.join(self.other_dir, cmd2)
+        self.create_file(other_file_path)
+
+        # pathext match in the first directory
+        self.assertNormEqual(shutil.which(cmd, path=search_path), other_file_path)
+        self.assertNormEqual(shutil.which(cmd, path=search_path, mode=os.F_OK),
+                             other_file_path)
+        # full match in the first directory
+        self.assertNormEqual(shutil.which(cmd2, path=search_path), other_file_path)
+        self.assertNormEqual(shutil.which(cmd2, path=search_path, mode=os.F_OK),
+                             other_file_path)
+
+        # full match in the first directory
+        search_path = os.pathsep.join([os.fsdecode(self.dir),
+                                       os.fsdecode(self.other_dir)])
+        self.assertEqual(shutil.which(cmd, path=search_path), self.filepath)
+        self.assertEqual(shutil.which(cmd, path=search_path, mode=os.F_OK),
+                         self.filepath)
 
-            # even though .exe2 is preferred in PATHEXT, we matched directly to test.exe
-            self.assertEqual(shutil.which(self.to_text_type("test.exe")), exe)
-            self.assertEqual(shutil.which(self.to_text_type("test")), exe2)
+    @unittest.skipUnless(sys.platform == "win32", 'test specific to Windows')
+    def test_dir_order_without_pathext_extension(self):
+        cmd = self.file[:-4]  # without .exe extension
+        search_path = os.pathsep.join([os.fsdecode(self.other_dir),
+                                       os.fsdecode(self.dir)])
+        # pathext match in the second directory
+        self.assertNormEqual(shutil.which(cmd, path=search_path), self.filepath)
+        self.assertNormEqual(shutil.which(cmd, path=search_path, mode=os.F_OK),
+                             self.filepath)
+
+        # without extension
+        other_file_path = os.path.join(self.other_dir, cmd)
+        self.create_file(other_file_path)
+
+        # pathext match in the second directory
+        self.assertNormEqual(shutil.which(cmd, path=search_path), self.filepath)
+        # full match in the first directory
+        self.assertNormEqual(shutil.which(cmd, path=search_path, mode=os.F_OK),
+                             other_file_path)
+        # full match in the second directory
+        self.assertNormEqual(shutil.which(self.file, path=search_path), self.filepath)
+        self.assertNormEqual(shutil.which(self.file, path=search_path, mode=os.F_OK),
+                             self.filepath)
+
+        # pathext match in the first directory
+        search_path = os.pathsep.join([os.fsdecode(self.dir),
+                                       os.fsdecode(self.other_dir)])
+        self.assertNormEqual(shutil.which(cmd, path=search_path), self.filepath)
+        self.assertNormEqual(shutil.which(cmd, path=search_path, mode=os.F_OK),
+                             self.filepath)
 
 
 class TestWhichBytes(TestWhich):
@@ -2548,18 +2614,12 @@ def setUp(self):
         TestWhich.setUp(self)
         self.dir = os.fsencode(self.dir)
         self.file = os.fsencode(self.file)
-        self.temp_file.name = os.fsencode(self.temp_file.name)
-        self.temp_dir = os.fsencode(self.temp_dir)
+        self.filepath = os.fsencode(self.filepath)
+        self.other_dir = os.fsencode(self.other_dir)
         self.curdir = os.fsencode(self.curdir)
         self.ext = os.fsencode(self.ext)
 
-    def to_text_type(self, s):
-        '''
-        In this class we're testing with bytes, so convert s to a bytes
-        '''
-        if isinstance(s, str):
-            return s.encode()
-        return s
+    to_text_type = staticmethod(os.fsencode)
 
 
 class TestMove(BaseTest, unittest.TestCase):
@@ -2570,8 +2630,7 @@ def setUp(self):
         self.dst_dir = self.mkdtemp()
         self.src_file = os.path.join(self.src_dir, filename)
         self.dst_file = os.path.join(self.dst_dir, filename)
-        with open(self.src_file, "wb") as f:
-            f.write(b"spam")
+        create_file(self.src_file, b"spam")
 
     def _check_move_file(self, src, dst, real_dst):
         with open(src, "rb") as f:
@@ -2649,8 +2708,7 @@ def test_move_dir_altsep_to_dir(self):
 
     def test_existing_file_inside_dest_dir(self):
         # A file with the same name inside the destination dir already exists.
-        with open(self.dst_file, "wb"):
-            pass
+        create_file(self.dst_file)
         self.assertRaises(shutil.Error, shutil.move, self.src_file, self.dst_dir)
 
     def test_dont_move_dir_in_itself(self):
@@ -3065,8 +3123,7 @@ def test_empty_file(self):
         dstname = TESTFN + 'dst'
         self.addCleanup(lambda: os_helper.unlink(srcname))
         self.addCleanup(lambda: os_helper.unlink(dstname))
-        with open(srcname, "wb"):
-            pass
+        create_file(srcname)
 
         with open(srcname, "rb") as src:
             with open(dstname, "wb") as dst:
@@ -3189,7 +3246,7 @@ def test_blocksize_arg(self):
             self.assertEqual(blocksize, os.path.getsize(TESTFN))
             # ...unless we're dealing with a small file.
             os_helper.unlink(TESTFN2)
-            write_file(TESTFN2, b"hello", binary=True)
+            create_file(TESTFN2, b"hello")
             self.addCleanup(os_helper.unlink, TESTFN2 + '3')
             self.assertRaises(ZeroDivisionError,
                               shutil.copyfile, TESTFN2, TESTFN2 + '3')
diff --git a/Misc/NEWS.d/next/Library/2024-11-22-10-42-34.gh-issue-127035.UnbDlr.rst b/Misc/NEWS.d/next/Library/2024-11-22-10-42-34.gh-issue-127035.UnbDlr.rst
new file mode 100644
index 00000000000000..6bb7abfdd50040
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-11-22-10-42-34.gh-issue-127035.UnbDlr.rst
@@ -0,0 +1,4 @@
+Fix :mod:`shutil.which` on Windows. Now it looks at direct match if and only
+if the command ends with a PATHEXT extension or X_OK is not in mode. Support
+extensionless files if "." is in PATHEXT. Support PATHEXT extensions that end
+with a dot.