Mocha@3 support

[a13o]

Based on the discussion in #206 this PR adds support for mocha v3.5.3.

The behavior of .only was modified to match the new behavior added in mocha 3.

Mocha 3 also introduces an overspecification exception if your test both returns a promise and uses the done hook. I removed this exception so overspecified tests will still work. It accomplishes this by effectively making every test async and ignoring the done hook.

[a13o]

I want to update the yarn.lock (even though the README says to use npm) but I keep getting this error. Anyone know how to get around this? I don't use yarn much.

yarn install v1.9.4
[1/5] Validating package.json...
[2/5] Resolving packages...
[3/5] Fetching packages...
error An unexpected error occurred: "http://ynpm-registry.corp.yahoo.com/@ember/test-helpers/-/test-helpers-0.7.18.tgz: connect ECONNREFUSED 68.142.238.39:80".

[rwjblue]

Likely the yarn lock accidentally checked in referring to a private registry (note the yahoo.com there).

[rwjblue]

I’m unsure how to force yarn to use a registry that isn’t what the yarn.lock has without just blowing away the yarn.lock...

[a13o]

Ahh, I see. I know it says not to at the top... but I edited yarn.lock to replace the yahoo registry entry with the one you get doing yarn add @ember/test-helpers@0.7.18 in a new project. Then I ran yarn. Seems like the diff makes sense. Only packages related to the mocha upgrade got bumped in the lockfile.

[Turbo87]

@a13o did you test these changes with a few projects? e.g. https://github.com/TryGhost/Ghost-Admin is a good open source project to test against

[a13o]

No, I'll start testing this with other projects using ember-mocha and report back. It's gonna take me some time to get to as my upcoming weekend is already full

[apellerano-pw]

I ran this branch today on a private repo with 6000+ tests across an app and an addon. I ran it on the suite both before and after we did the new testing api upgrade. Worked in all cases!

Let's keep documenting successes so we can build confidence in the PR or fix any issues found

[Turbo87]

that's good to hear, thanks @apellerano-pw!

[a13o]

Tested this on Ghost-Admin, it seems to break in tests with done hooks. Needs further investigation

[a13o]

I think my approach to squelching the overspecification error is wrong. It might have to go in the other direction and modify the wrapper function in the adapter to always return a promise, rather than always use a done hook. The done hook would then never actually be given to mocha and can be re-implemented in the adapter to resolve the promise that mocha was given. That means mocha never sees both a returned promise and done hook in the same test, and the error is squelched. And we can detect the arity of the test function before executing it whereas we have to execute it to find out if it returns a promise. So standardizing on the promise seems like the way to go.

It's gonna take a bigger rewrite than I thought. My time is limited to work on this but I'll keep pushing when I can and leaving updates here. The next step is I believe I can write test cases now for what we need.

I'm not sure what the long term plans are for this project; has the possibility of a major version bump and breaking change been discussed? If so I would rather yield to that than continue this approach of removing official mocha functionality in the name of backwards compatibility. Every day we stray further from mocha's light 😛

[Turbo87]

has the possibility of a major version bump and breaking change been discussed? If so I would rather yield to that than continue this approach of removing official mocha functionality in the name of backwards compatibility. Every day we stray further from mocha's light 😛

yeah, it had been discussed. but back then the new testing API was still very young and we decided to keep support for the old one for now. the new API has been around for some time now though, so maybe it's time to deprecate the old API. on the other hand ember-cli-mocha is still not updated to the new API yet... 😞