def METHOD_NAME(self, reddit):
    reddit.read_only = False
    message1 = next(reddit.inbox.messages(limit=1))
    assert isinstance(message1, SubredditMessage)
    message_fullname = message1.fullname
    message1.block()
    message2 = next(reddit.inbox.messages(limit=1))
    assert message2.fullname == message_fullname
    assert message2.subject == "[message from blocked subreddit]"
    message2.unblock_subreddit()
    message3 = next(reddit.inbox.messages(limit=1))
    assert message3.fullname == message_fullname
    assert message3.subject != "[message from blocked subreddit]"