Issue #26146: marshal.loads() now uses the empty frozenset singleton

1 files changed, 7 insertions, 0 deletions

diff --git a/Lib/test/test_marshal.py b/Lib/test/test_marshal.py
index c7def9a599..b378ffea00 100644
--- a/Lib/test/test_marshal.py
+++ b/Lib/test/test_marshal.py
@@ -135,6 +135,13 @@ class ContainerTestCase(unittest.TestCase, HelperMixin):
         for constructor in (set, frozenset):
             self.helper(constructor(self.d.keys()))
 
+    @support.cpython_only
+    def test_empty_frozenset_singleton(self):
+        # marshal.loads() must reuse the empty frozenset singleton
+        obj = frozenset()
+        obj2 = marshal.loads(marshal.dumps(obj))
+        self.assertIs(obj2, obj)
+
 
 class BufferTestCase(unittest.TestCase, HelperMixin):