mapping_tests.py 文件源码

def test_fromkeys(self):
        TestMappingProtocol.test_fromkeys(self)
        class mydict(self.type2test):
            def __new__(cls):
                return collections.UserDict()
        ud = mydict.fromkeys('ab')
        self.assertEqual(ud, {'a':None, 'b':None})
        self.assertIsInstance(ud, collections.UserDict)