test_collections.py 文件源码

def test_MutableMapping_subclass(self):
        # Test issue 9214
        mymap = UserDict()
        mymap['red'] = 5
        self.assertIsInstance(mymap.keys(), Set)
        self.assertIsInstance(mymap.keys(), KeysView)
        self.assertIsInstance(mymap.items(), Set)
        self.assertIsInstance(mymap.items(), ItemsView)

        mymap = UserDict()
        mymap['red'] = 5
        z = mymap.keys() | {'orange'}
        self.assertIsInstance(z, set)
        list(z)
        mymap['blue'] = 7               # Shouldn't affect 'z'
        self.assertEqual(sorted(z), ['orange', 'red'])

        mymap = UserDict()
        mymap['red'] = 5
        z = mymap.items() | {('orange', 3)}
        self.assertIsInstance(z, set)
        list(z)
        mymap['blue'] = 7               # Shouldn't affect 'z'
        self.assertEqual(sorted(z), [('orange', 3), ('red', 5)])