Add back test_realpath_unreadable_symlink_strict

This one passes on MacOS, and gives some test coverage for OSErrors
other than missing files.

Author: encukou

Lib/test/test_posixpath.py

@@ -795,6 +795,27 @@ def test_realpath_resolve_first(self, kwargs):
             safe_rmdir(ABSTFN + "/k")
             safe_rmdir(ABSTFN)
 
+    @os_helper.skip_unless_symlink
+    @skip_if_ABSTFN_contains_backslash
+    @unittest.skipIf(os.chmod not in os.supports_follow_symlinks, "Can't set symlink permissions")
+    @unittest.skipIf(sys.platform != "darwin", "only macOS requires read permission to readlink()")
+    @_parameterize({'strict': True}, {'strict': ALLOW_MISSING})
+    def test_realpath_unreadable_symlink_strict(self, kwargs):
+        try:
+            os.symlink(ABSTFN+"1", ABSTFN)
+            os.chmod(ABSTFN, 0o000, follow_symlinks=False)
+            with self.assertRaises(PermissionError):
+                realpath(ABSTFN, **kwargs)
+            with self.assertRaises(PermissionError):
+                realpath(ABSTFN + '/foo', **kwargs),
+            with self.assertRaises(PermissionError):
+                realpath(ABSTFN + '/../foo', **kwargs)
+            with self.assertRaises(PermissionError):
+                realpath(ABSTFN + '/foo/..', **kwargs)
+        finally:
+            os.chmod(ABSTFN, 0o755, follow_symlinks=False)
+            os.unlink(ABSTFN)
+
     @skip_if_ABSTFN_contains_backslash
     @os_helper.skip_unless_symlink
     def test_realpath_unreadable_directory(self):