Method test_union_operators

Lib/test/test_collections.py:266–310

(self)

        self.assertEqual(d.maps, [{'b': 20, 'c': 30}, {'a': 1, 'b': 2}])

    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
        tmp = cm3.copy()
        cm3 |= pairs
        self.assertEqual(cm3.maps, [tmp.maps[0] | dict(pairs), *tmp.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)


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