gh-124722: Fix leak in `test_detach_materialized_dict_no_memory` (GH-124769)

Lib/test/test_class.py

@@ -1,7 +1,7 @@
 "Test the functionality of Python classes implementing operators."
 
 import unittest
-import test.support
+from test.support import cpython_only, import_helper, script_helper
 
 testmeths = [
 
@@ -933,8 +933,15 @@ class TestInlineValues(unittest.TestCase):
         C.a = X()
         C.a = X()
 
+    @cpython_only
     def test_detach_materialized_dict_no_memory(self):
+        # Skip test if _testcapi is not available:
+        import_helper.import_module('_testcapi')
+
+        code = """if 1:
+            import test.support
             import _testcapi
+
             class A:
                 def __init__(self):
                     self.a = 1
@@ -944,9 +951,18 @@ class TestInlineValues(unittest.TestCase):
             with test.support.catch_unraisable_exception() as ex:
                 _testcapi.set_nomemory(0, 1)
                 del a
-            self.assertEqual(ex.unraisable.exc_type, MemoryError)
-        with self.assertRaises(KeyError):
+                assert ex.unraisable.exc_type is MemoryError
+            try:
                 d["a"]
+            except KeyError:
+                pass
+            else:
+                assert False, "KeyError not raised"
+        """
+        rc, out, err = script_helper.assert_python_ok("-c", code)
+        self.assertEqual(rc, 0)
+        self.assertFalse(out, msg=out.decode('utf-8'))
+        self.assertFalse(err, msg=err.decode('utf-8'))
 
 if __name__ == '__main__':
     unittest.main()