Fix unresolvable promises

[vasinkd]

Situation:
We use ConversationHandler with run_async decorator and an entry_point function returns None

Result:
We stuck within conversation state (None, Promise) since Promise returns None and None means we do not update conversation state.

Solution:
If Promise returns None AND old state is None - exit Conversation Handler.

Caveats:
May be not suitable if a programmer uses None as a valid state in Conversation states dict. But why would anyone do that?

[jh0ker]

Good catch, thanks for your contribution!

This also seems to be the behavior for when a synchronous entry point handler returns None, although this is never explicitly documented. Perhaps it would be a good idea to do so.

It would also be great if you could add a unit test that tests for this bug, so we won't have any regressions in the future. It should probably look similar to this test.

Edit: I don't think the caveat you mentioned is real, pretty sure it is already not possible to use None for states

[jh0ker]

Needs a test and documentation

[jsmnbom]

@vasinkd is test and docs something you would like to do an attempt at?

[vasinkd]

Totally forgot about this. @jsmnbom , thanks for a reminder!

Ok, I'll add tests, no problemo.
What about documentation? Should I mention this behavior in ConversationHandler class description?

[jsmnbom]

Thanks a lot :D
In terms of docs I was mostly referring to @jh0ker's comment about

This also seems to be the behavior for when a synchronous entry point handler returns None, although this is never explicitly documented. Perhaps it would be a good idea to do so.

So a note in the ConversationHandler class docstring about this behaviour (both sync and async) sounds good yea :)

[vasinkd]

Done. Sorry for the delay!
Better late than never :)

[Eldinnie]

Test for this instance passed. Can we merge for V12 @jsmnbom ?

[jsmnbom]

I see what you mean. Yea let's merge it :)

[Eldinnie]

CI is running, should be able to be merged in v12

[Eldinnie]

Merged V12 after making small adjustment there regarding conversationhandler. If CI agrees we can merge.

not reviewed since last changes