test_struct.py 文件源码

def test_unpack_from(self):
        test_string = b'abcd01234'
        fmt = '4s'
        s = struct.Struct(fmt)
        for cls in (bytes, bytearray):
            data = cls(test_string)
            self.assertEqual(s.unpack_from(data), (b'abcd',))
            self.assertEqual(s.unpack_from(data, 2), (b'cd01',))
            self.assertEqual(s.unpack_from(data, 4), (b'0123',))
            for i in range(6):
                self.assertEqual(s.unpack_from(data, i), (data[i:i+4],))
            for i in range(6, len(test_string) + 1):
                self.assertRaises(struct.error, s.unpack_from, data, i)
        for cls in (bytes, bytearray):
            data = cls(test_string)
            self.assertEqual(struct.unpack_from(fmt, data), (b'abcd',))
            self.assertEqual(struct.unpack_from(fmt, data, 2), (b'cd01',))
            self.assertEqual(struct.unpack_from(fmt, data, 4), (b'0123',))
            for i in range(6):
                self.assertEqual(struct.unpack_from(fmt, data, i), (data[i:i+4],))
            for i in range(6, len(test_string) + 1):
                self.assertRaises(struct.error, struct.unpack_from, fmt, data, i)