Improving Testability of Handlers v2

[NateBarnes]

Ok, here's v2 of the work to improve the testability of handlers. This extracts the Outbound functions of the chat backend into a behaviour, then implements that behavior into a SlackOutbound module. This allows us to create a Spy of this Behaviour to capture outbound replies. I've updated the internal tests of the handler helpers, and then added a few tests for some of the internal handlers to reflect the new style. I've also created some macros to make it easier for people to implement the most common flows in by using Alice.Handlers.Case.

I also updated alice_roller in a separate branch so you can see what tests look like in a third party handler as well: https://github.com/NateBarnes/alice_roller/blob/testing-refactor/test/alice/handlers/roller_test.exs

I believe this should resolve #47 . Let me know what y'all think though

[adamzaninovich]

I love how this turned out! Can't wait to use it to actually test all these handlers with zero coverage!

Here are a few things I saw.

[adamzaninovich]

You might want to run the formatter, but other than that it looks good to me.

[NateBarnes]

Ok, formatter has been run, ran credo while I was at it, and wrote a bunch of documentation for the new modules and methods.

[adamzaninovich]

Looks great!

[tielur]

❤️