bpo-31107: Fix copyreg mangled slot names calculation. (#2989)

1 files changed, 10 insertions, 0 deletions

diff --git a/Lib/test/test_copyreg.py b/Lib/test/test_copyreg.py
index 52e887cb36..e3f1cd81aa 100644
--- a/Lib/test/test_copyreg.py
+++ b/Lib/test/test_copyreg.py
@@ -16,6 +16,12 @@ class WithWeakref(object):
 class WithPrivate(object):
     __slots__ = ('__spam',)
 
+class _WithLeadingUnderscoreAndPrivate(object):
+    __slots__ = ('__spam',)
+
+class ___(object):
+    __slots__ = ('__spam',)
+
 class WithSingleString(object):
     __slots__ = 'spam'
 
@@ -104,6 +110,10 @@ class CopyRegTestCase(unittest.TestCase):
         self.assertEqual(copyreg._slotnames(WithWeakref), [])
         expected = ['_WithPrivate__spam']
         self.assertEqual(copyreg._slotnames(WithPrivate), expected)
+        expected = ['_WithLeadingUnderscoreAndPrivate__spam']
+        self.assertEqual(copyreg._slotnames(_WithLeadingUnderscoreAndPrivate),
+                         expected)
+        self.assertEqual(copyreg._slotnames(___), ['__spam'])
         self.assertEqual(copyreg._slotnames(WithSingleString), ['spam'])
         expected = ['eggs', 'spam']
         expected.sort()