2 files changed, 82 insertions, 0 deletions
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 92520b09bb..47c500bcdd 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -232,6 +232,51 @@ class TestChainMap(unittest.TestCase):
         for k, v in dict(a=1, B=20, C=30, z=100).items():             # check get
             self.assertEqual(d.get(k, 100), v)
 
+    def test_union_operators(self):
+        cm1 = ChainMap(dict(a=1, b=2), dict(c=3, d=4))
+        cm2 = ChainMap(dict(a=10, e=5), dict(b=20, d=4))
+        cm3 = cm1.copy()
+        d = dict(a=10, c=30)
+        pairs = [('c', 3), ('p',0)]
+
+        tmp = cm1 | cm2 # testing between chainmaps
+        self.assertEqual(tmp.maps, [cm1.maps[0] | dict(cm2), *cm1.maps[1:]])
+        cm1 |= cm2
+        self.assertEqual(tmp, cm1)
+
+        tmp = cm2 | d # testing between chainmap and mapping
+        self.assertEqual(tmp.maps, [cm2.maps[0] | d, *cm2.maps[1:]])
+        self.assertEqual((d | cm2).maps, [d | dict(cm2)])
+        cm2 |= d
+        self.assertEqual(tmp, cm2)
+
+        # testing behavior between chainmap and iterable key-value pairs
+        with self.assertRaises(TypeError):
+            cm3 | pairs
+        cm3 |= pairs
+        self.assertEqual(cm3.maps, [cm3.maps[0] | dict(pairs), *cm3.maps[1:]])
+
+        # testing proper return types for ChainMap and it's subclasses
+        class Subclass(ChainMap):
+            pass
+
+        class SubclassRor(ChainMap):
+            def __ror__(self, other):
+                return super().__ror__(other)
+
+        tmp = ChainMap() | ChainMap()
+        self.assertIs(type(tmp), ChainMap)
+        self.assertIs(type(tmp.maps[0]), dict)
+        tmp = ChainMap() | Subclass()
+        self.assertIs(type(tmp), ChainMap)
+        self.assertIs(type(tmp.maps[0]), dict)
+        tmp = Subclass() | ChainMap()
+        self.assertIs(type(tmp), Subclass)
+        self.assertIs(type(tmp.maps[0]), dict)
+        tmp = ChainMap() | SubclassRor()
+        self.assertIs(type(tmp), SubclassRor)
+        self.assertIs(type(tmp.maps[0]), dict)
+
 
 ################################################################################
 ### Named Tuples
diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index 63c725527d..250ed40b20 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -1624,6 +1624,43 @@ class MappingTestCase(TestBase):
         self.assertEqual(len(d), 1)
         self.assertEqual(list(d.keys()), [o2])
 
+    def test_weak_keyed_union_operators(self):
+        o1 = C()
+        o2 = C()
+        o3 = C()
+        wkd1 = weakref.WeakKeyDictionary({o1: 1, o2: 2})
+        wkd2 = weakref.WeakKeyDictionary({o3: 3, o1: 4})
+        wkd3 = wkd1.copy()
+        d1 = {o2: '5', o3: '6'}
+        pairs = [(o2, 7), (o3, 8)]
+
+        tmp1 = wkd1 | wkd2 # Between two WeakKeyDictionaries
+        self.assertEqual(dict(tmp1), dict(wkd1) | dict(wkd2))
+        self.assertIs(type(tmp1), weakref.WeakKeyDictionary)
+        wkd1 |= wkd2
+        self.assertEqual(wkd1, tmp1)
+
+        tmp2 = wkd2 | d1 # Between WeakKeyDictionary and mapping
+        self.assertEqual(dict(tmp2), dict(wkd2) | d1)
+        self.assertIs(type(tmp2), weakref.WeakKeyDictionary)
+        wkd2 |= d1
+        self.assertEqual(wkd2, tmp2)
+
+        tmp3 = wkd3.copy() # Between WeakKeyDictionary and iterable key, value
+        tmp3 |= pairs
+        self.assertEqual(dict(tmp3), dict(wkd3) | dict(pairs))
+        self.assertIs(type(tmp3), weakref.WeakKeyDictionary)
+
+        tmp4 = d1 | wkd3 # Testing .__ror__
+        self.assertEqual(dict(tmp4), d1 | dict(wkd3))
+        self.assertIs(type(tmp4), weakref.WeakKeyDictionary)
+
+        del o1
+        self.assertNotIn(4, tmp1.values())
+        self.assertNotIn(4, tmp2.values())
+        self.assertNotIn(1, tmp3.values())
+        self.assertNotIn(1, tmp4.values())
+
     def test_weak_valued_delitem(self):
         d = weakref.WeakValueDictionary()
         o1 = Object('1')