bpo-25803: Avoid incorrect errors raised by Path.mkdir(exist_ok=True) (#805)

when the OS gives priority to errors such as EACCES over EEXIST.

1 files changed, 5 insertions, 0 deletions

diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index 88a93e5802..3ff9726d43 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -1776,6 +1776,11 @@ class _BasePathTest(object):
         self.assertTrue(p.exists())
         self.assertEqual(p.stat().st_ctime, st_ctime_first)
 
+    def test_mkdir_exist_ok_root(self):
+        # Issue #25803: A drive root could raise PermissionError on Windows
+        self.cls('/').resolve().mkdir(exist_ok=True)
+        self.cls('/').resolve().mkdir(parents=True, exist_ok=True)
+
     @only_nt    # XXX: not sure how to test this on POSIX
     def test_mkdir_with_unknown_drive(self):
         for d in 'ZYXWVUTSRQPONMLKJIHGFEDCBA':