test_codecs.py 文件源码

def test_open(self):
        self.addCleanup(support.unlink, support.TESTFN)
        for mode in ('w', 'r', 'r+', 'w+', 'a', 'a+'):
            with self.subTest(mode), \
                    codecs.open(support.TESTFN, mode, 'ascii') as file:
                self.assertIsInstance(file, codecs.StreamReaderWriter)