def METHOD_NAME(self):
    """test TaskMsgTree enabling at runtime (v1.7)"""
    class HotEH2(EventHandler):
        def ev_read(self, worker):
            worker.task.set_default("stdout_msgtree", True)
            worker.task.shell("echo foo bar2") # default EH
    task = task_self()
    task.set_default("stdout_msgtree", False)
    self.assertEqual(task.default("stdout_msgtree"), False)
    worker = task.shell("echo foo bar", handler=HotEH2())
    task.resume()
    # only second message has been recorded
    for buf, keys in task.iter_buffers():
        self.assertEqual(buf, "foo bar2")