def METHOD_NAME(self):
    args = ("a", "b", "c", "d", "e")
    for n in range(6):
        e = BlockingIOError(*args[:n])
        with self.assertRaises(AttributeError):
            e.characters_written
    e = BlockingIOError("a", "b", 3)
    self.assertEqual(e.characters_written, 3)
    e.characters_written = 5
    self.assertEqual(e.characters_written, 5)