🍽 Downstream apps can't reliably test async listeners

[tteltrab]

Description

Trying to manage testing of a bolt app and running into some issues with reliably handling async - request handlers are resolving before messages have been handled. Wrote up a couple of test cases and opened a PR here to show them failing: #337

We have business logic in async handlers (pretty common pattern?) and ideally we'd be able to handle the response when it comes from that async pattern. Example PR shows three failing cases.

What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• testing related
• discussion

Requirements (place an x in each of the [ ])

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.

[stevengill]

Thanks for the issue and PR @tteltrab. I'll bring this to the attention of a colleague.

[stevengill]

@aoberoi Any chance you can check this one out when you have some spare cycles?

[aoberoi]

Left a comment in the PR linked above which outlines some approaches we could use to fix the issue.

[aoberoi]

With the release of Bolt for JS v2, you can now test listeners more reliably.

We've demonstrated a pattern for this in Bolt's own tests, using the FakeReceiver class. Once you initialize an App with that receiver, you can call await fakeReceiver.sendEvent(somePayload) and the following line of code will execute after all the listeners have had a chance to process the event. No more arbitrary delays!