bpo-36144: Implement defaultdict union (GH-18729)
For PEP 585 (this isn't in the PEP but is an obvious follow-up).
diff --git a/Lib/test/test_defaultdict.py b/Lib/test/test_defaultdict.py
index b9f1fb9..b48c649 100644
--- a/Lib/test/test_defaultdict.py
+++ b/Lib/test/test_defaultdict.py
@@ -183,5 +183,43 @@
o = pickle.loads(s)
self.assertEqual(d, o)
+ def test_union(self):
+ i = defaultdict(int, {1: 1, 2: 2})
+ s = defaultdict(str, {0: "zero", 1: "one"})
+
+ i_s = i | s
+ self.assertIs(i_s.default_factory, int)
+ self.assertDictEqual(i_s, {1: "one", 2: 2, 0: "zero"})
+ self.assertEqual(list(i_s), [1, 2, 0])
+
+ s_i = s | i
+ self.assertIs(s_i.default_factory, str)
+ self.assertDictEqual(s_i, {0: "zero", 1: 1, 2: 2})
+ self.assertEqual(list(s_i), [0, 1, 2])
+
+ i_ds = i | dict(s)
+ self.assertIs(i_ds.default_factory, int)
+ self.assertDictEqual(i_ds, {1: "one", 2: 2, 0: "zero"})
+ self.assertEqual(list(i_ds), [1, 2, 0])
+
+ ds_i = dict(s) | i
+ self.assertIs(ds_i.default_factory, int)
+ self.assertDictEqual(ds_i, {0: "zero", 1: 1, 2: 2})
+ self.assertEqual(list(ds_i), [0, 1, 2])
+
+ with self.assertRaises(TypeError):
+ i | list(s.items())
+ with self.assertRaises(TypeError):
+ list(s.items()) | i
+
+ # We inherit a fine |= from dict, so just a few sanity checks here:
+ i |= list(s.items())
+ self.assertIs(i.default_factory, int)
+ self.assertDictEqual(i, {1: "one", 2: 2, 0: "zero"})
+ self.assertEqual(list(i), [1, 2, 0])
+
+ with self.assertRaises(TypeError):
+ i |= None
+
if __name__ == "__main__":
unittest.main()