Add documentation on how to test methods that return promises, linked…

[kobbikobb]

Issue #1898 is stale and talks about missing documentation for promises. Is this something we would like?

I can change the code to use dependency injection if we think more developers would use that. If we want that we need to decide constructor or property injection... :)

Purpose (TL;DR) - mandatory

How to verify - mandatory

1. Check out this branch
2. npm install

Checklist for author

• npm run lint passes
• References to standard library functions are cached.

[coveralls]

Pull Request Test Coverage Report for Build 2918

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.186%

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Totals
Change from base Build 2911:	0.0%
Covered Lines:	1660
Relevant Lines:	1729

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💛 - Coveralls

[fatso83]

Coincidentally, I looked into all of these issues yesterday and actually followed up on this! Weird timing :)

@orlangure already made a significant effort on this in #1931, which have unfortunately stalled for some time, but I think I'm merging this within a week. I'd rather have this build-upon that work, if that is fine with you? I'll ensure it doesn't drag on any longer than it needs to. Working beats perfect any day :)

So, if you could just set this aside for a week, I'd just copy-paste the additions into the (soon to be) existing article.

[fatso83]

OK, #1931 has been merged. Could you see if you have stuff that is uncovered in https://github.com/sinonjs/sinon/blob/master/docs/_howto/lolex-async-promises.md and copy it in?

[kobbikobb]

@fatso83 my examples are realistic and show how to test simple async code with stubs and different arguments.

Lolex is intended for more complex scenarios, f.x. setTimeout, setInterval...

I think some developers might benefit in some opinionated and simple ways of testing async code.
The developers I work with thought you needed to call a done callback but that is not the case and they tend to not to test async code because they think it is too complicated.

I am open to anything if we want to move it, change it or combine this with other documentation.
You might think this is too general for our documentation and maybe it is.

What do you think? :D

[fatso83]

Right now, it's a demo of Mocha's API, along with some examples on doing async tests - which happen to use Promises. I think this is fine, but it's covering a bit of different ground than we were originally thinking of with #1898. I think your doc is basically the complement to your previous addition: https://github.com/sinonjs/sinon/blob/master/docs/_howto/stub-dependency.md.

Maybe it would fit better there, as a section on how to stub out dependencies that are async? It could have your existing stuff, but possibly also an example on doing the same for classic callback passing async code.

[kobbikobb]

@fatso83 Good idea, I was thinking the same thing. I added them together and improved some texts.

The thing that is now bothering me is that the examples: simple and asynchronous are not working on the same codebase(one is more real like...). Maybe it does not matter.

What do you think, any feedback?

[mroderick]

I don't think the echo file was really necessary here ...