bpo-40890: Add `mapping` property to dict views (GH-20749)
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 5c08810..9ff8b7d 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -105,6 +105,26 @@
self.assertRaises(TypeError, d.items, None)
self.assertEqual(repr(dict(a=1).items()), "dict_items([('a', 1)])")
+ def test_views_mapping(self):
+ mappingproxy = type(type.__dict__)
+ class Dict(dict):
+ pass
+ for cls in [dict, Dict]:
+ d = cls()
+ m1 = d.keys().mapping
+ m2 = d.values().mapping
+ m3 = d.items().mapping
+
+ for m in [m1, m2, m3]:
+ self.assertIsInstance(m, mappingproxy)
+ self.assertEqual(m, d)
+
+ d["foo"] = "bar"
+
+ for m in [m1, m2, m3]:
+ self.assertIsInstance(m, mappingproxy)
+ self.assertEqual(m, d)
+
def test_contains(self):
d = {}
self.assertNotIn('a', d)