pythonGH-89812: Improve test for pathlib.Path.stat() (pythonGH-106064)

Make assertions about the `st_mode`, `st_ino` and `st_dev` attributes of
the stat results from two files and a directory, rather than checking if
`chmod()` affects `st_mode` (which is already tested elsewhere).

Lib/test/test_pathlib.py

@@ -2145,15 +2145,25 @@ def test_resolve_dot(self):
  # Non-strict
  self.assertEqual(r.resolve(strict=False), p / '3' / '4')
 
- @os_helper.skip_unless_working_chmod
  def test_stat(self):
- p = self.cls(BASE) / 'fileA'
- st = p.stat()
- self.assertEqual(p.stat(), st)
- # Change file mode by flipping write bit.
- p.chmod(st.st_mode ^ 0o222)
- self.addCleanup(p.chmod, st.st_mode)
- self.assertNotEqual(p.stat(), st)
+ statA = self.cls(BASE).joinpath('fileA').stat()
+ statB = self.cls(BASE).joinpath('dirB', 'fileB').stat()
+ statC = self.cls(BASE).joinpath('dirC').stat()
+ # st_mode: files are the same, directory differs.
+ self.assertIsInstance(statA.st_mode, int)
+ self.assertEqual(statA.st_mode, statB.st_mode)
+ self.assertNotEqual(statA.st_mode, statC.st_mode)
+ self.assertNotEqual(statB.st_mode, statC.st_mode)
+ # st_ino: all different,
+ self.assertIsInstance(statA.st_ino, int)
+ self.assertNotEqual(statA.st_ino, statB.st_ino)
+ self.assertNotEqual(statA.st_ino, statC.st_ino)
+ self.assertNotEqual(statB.st_ino, statC.st_ino)
+ # st_dev: all the same.
+ self.assertIsInstance(statA.st_dev, int)
+ self.assertEqual(statA.st_dev, statB.st_dev)
+ self.assertEqual(statA.st_dev, statC.st_dev)
+ # other attributes not used by pathlib.
 
  def test_stat_no_follow_symlinks(self):
  if not self.can_symlink: