mqtt: fix unexpected behaviour

[stintel]

Currently mqtt_response with the unexpected key set to true fails if no message is received. This is strange, was we don't expect a message, and should only fail if a message is received.

Formatted stage:
  mqtt_publish:
    payload: 10.10.10.10
    topic: inet6/add
  mqtt_response:
    payload: !anything ''
    timeout: 5
    topic: vallumd/will
    unexpected: true

Errors:
E   tavern.util.exceptions.TestFailError: Test 'add IPv4 IP to IPv6 ipset' failed:
    - Expected '<Tavern YAML sentinel for anything>' on topic 'vallumd/will' but no such message received

Fix this by suppressing the error MQTTResponse._await_response() and returning an empty dict if the unexpected key is set.

Signed-off-by: Stijn Tintel [email protected]

[michaelboulton]

Suggested change

	if self.expected.get("unexpected"):
	return {}
	else:
	self._adderr(
	"Expected '%s' on topic '%s' but no such message received",
	expected_payload,
	topic,
	)
	if not self.expected.get("unexpected"):
	self._adderr(
	"Expected '%s' on topic '%s' but no such message received",
	expected_payload,
	topic,
	)

Returning early will break the saving of variables from responses, this should do what is required

[stintel]

I believe I tried that at first and hit other errors. Let me retry.

[stintel]

Indeed: tavern.txt

[stintel]

My initial submission works, your suggestion including my extra attempts to fix it, doesn't. Any other ideas/suggestions?

[michaelboulton]

Sorry, I've been looking at the 'multiple mqtt responses' feature in Tavern 2.0 and wasn't thinking about there only being one mqtt response.

I think that what needs to be done is that my suggestion does need to be applied, but then also just after it checks if there were any errors (

tavern/tavern/_plugins/mqtt/response.py

Lines 190 to 197 in 540588f

	if self.errors:
	if warnings:
	self._adderr("\n".join(warnings))
	raise exceptions.TestFailError(
	"Test '{:s}' failed:\n{:s}".format(self.name, self._str_errors()),
	failures=self.errors,
	)

) it should do

if not msg:
    return {}

because there won't be any variables to save.

[stintel]

Made a slight alteration to your suggestion, seems to work like that. Let me know if that's OK for you?

[michaelboulton]

I think the CI has randomly broken again, will try to fix it

[stintel]

I think the CI has randomly broken again, will try to fix it

Thanks, no rush, I can pip install tavern from my branch which allows me to continue working on the CI I'm using it in!

[felixbohnus]

I also stumbled over this bug and tested the proposed solution with the local installation. I'm not sure about the processes: should I create a new pull request or should this pull request be updated?