check local class namespace before reaching for cells (closes #17853)

1 files changed, 13 insertions, 0 deletions

diff --git a/Lib/test/test_scope.py b/Lib/test/test_scope.py
index 129a18aade..f4ed2442c6 100644
--- a/Lib/test/test_scope.py
+++ b/Lib/test/test_scope.py
@@ -714,6 +714,19 @@ class ScopeTests(unittest.TestCase):
             global a
 
 
+    def testClassNamespaceOverridesClosure(self):
+        # See #17853.
+        x = 42
+        class X:
+            locals()["x"] = 43
+            y = x
+        self.assertEqual(X.y, 43)
+        class X:
+            locals()["x"] = 43
+            del x
+        self.assertFalse(hasattr(X, "x"))
+        self.assertEqual(x, 42)
+
 
 def test_main():
     run_unittest(ScopeTests)