gistfile1.txt

class TestHardPDAQCrash(TestLiveControlWithPDAQ):
    def test(self):
        assert 'OK' == livecmd("config set -i default")
	assert 'OK' == livecmd("altconfigs add -i alt1")
        assert 'OK' == livecmd("start daq")
	# Simulate hard crash of pDAQ:
        self.toy.close()

        # Lexical closure to collect complete set of log messages:
	def message_updater():
            msgs = []
            def update_msgs():
                msgs.extend(drain_queue(self.sink))
            def messages_received_so_far():
		update_msgs()
                return msgs
            return messages_received_so_far

        allmsgs = message_updater()

        def correct_recovery_failure_messages_generated():
            all = allmsgs()
	    moni = [x["payload"] for x in all if x["cmd"] == "moni"]
            logs = [x["value"] for x in moni if x["varname"] == "log"]
            recovery_fail_msgs = filter(
                lambda x: "failed and did not generate any events" in x,
                logs)
            failed_configs = [re.findall("config (\S+) failed", m)[0]
                              for m in recovery_fail_msgs]
            return failed_configs == (["default" for _ in range(4)] +
                                      ["alt1" for _ in range(4)])

	misc.wait_until(correct_recovery_failure_messages_generated)

Why not turn

def message_updater():
    msgs = []
    def update_msgs():
        msgs.extend(drain_queue(self.sink))
    def messages_received_so_far():
        update_msgs()
        return msgs
    return messages_received_so_far
allmsgs = message_updater()

into

_msgs = []
def allmsgs():
    _msgs.extend(drain_queue(self.sink))
    return _msgs

Python has weird scoping rules for variables within functions, so I didn't try it that way at the beginning -- trying it now, though

You are right , that works -- even better, thanks! Code reviews FTW. I can't remember under what conditions I've been screwed by function-local variables before, but it's definitely quirky in python.

I've done something like the following before

def allmsgs():
    allmsgs._msgs.extend(drain_queue(self.sink))
    return allmsgs._msgs
allmsgs._msgs = []

This is very clearly complecting functions and data. It works though and appears to be what you want.