Issue #20639: calling Path.with_suffix('') allows removing the suffix again.

Patch by July Tikhonov.

1 files changed, 3 insertions, 4 deletions

diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index c1ec07a..48b7031 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -759,11 +759,10 @@ class PurePath(object):
     def with_suffix(self, suffix):
         """Return a new path with the file suffix changed (or added, if none)."""
         # XXX if suffix is None, should the current suffix be removed?
-        drv, root, parts = self._flavour.parse_parts((suffix,))
-        if drv or root or len(parts) != 1:
+        f = self._flavour
+        if f.sep in suffix or f.altsep and f.altsep in suffix:
             raise ValueError("Invalid suffix %r" % (suffix))
-        suffix = parts[0]
-        if not suffix.startswith('.'):
+        if suffix and not suffix.startswith('.') or suffix == '.':
             raise ValueError("Invalid suffix %r" % (suffix))
         name = self.name
         if not name: