Nodejs 7.2 async/await

[gbahamondezc]

I'm using NodeJS 7 + gulp-istanbul for my test coverage and i'm getting Unexpected identifier with a async method of a class.

    class SomeClass {
        async someMethod() {
            return await  somePromise();
        }
    }

Is this issue related direct with Istanbul?
If so, there's some way to support this case?

[BrandonZacharie]

I get a bunch or errors that look like

Transformation error; return original code
{ Error: Line 22: Unexpected token =>
    at constructError (node_modules/esprima/esprima.js:2407:21)
    at createError (node_modules/esprima/esprima.js:2426:17)
    at unexpectedTokenError (node_modules/esprima/esprima.js:2500:13)
    at throwUnexpectedToken (node_modules/esprima/esprima.js:2505:15)
    at consumeSemicolon (node_modules/esprima/esprima.js:2620:13)
    ...

Maybe esprima needs to be upgraded or patched.

[sabakugaara]

@gbahamondezc, istanbul shuold be ^1.0.0 and try this:

node --harmony ./node_modules/.bin/istanbul cover ./node_modules/.bin/_mocha -- tests/*

[kevinludwig]

@sabakugaara the most recent version of istanbul is 0.4.5; do you mean gulp-istanbul >= 1.0.0? Also as far as I can tell, the problem is that the parser being used is esprima, and it does not yet support async/await it only claims to support ES2016. So I think the answer here is that esprima needs to support ES2017 and then istanbul needs to be upgraded to a compliant version of esprima, and then gulp-istanbul needs to be bumped to take that new version of istanbul. If you'd like to verify for yourself that this is the case, you can look at the esprima online parser, just type in a simple do nothing async function and it will complain: http://esprima.org/demo/parse.html.

[sabakugaara]

@kevinludwig try this: istanbul 1.1-alpha

[kevinludwig]

npm ERR! No compatible version found: [email protected]
npm ERR! Valid install targets:
npm ERR! 1.1.1, 1.1.0, 1.0.0, 0.10.4, 0.10.3, 0.10.2, 0.10.1, 0.10.0, 0.9.0, 0.8.1, 0.8.0, 0.7.0, 0.6.0, 0.5.0, 0.4.0, 0.3.1, 0.3.0, 0.2.2, 0.2.1, 0.2.0, 0.1.1, 0.1.0

[sabakugaara]

maybe gulp-istanbul should update dependencies https://github.com/SBoudrias/gulp-istanbul/blob/master/package.json#L32

[kevinludwig]

don't think that helps. Latest version of istanbul is 0.4.5 and the version specified by gulp-istanbul is ^0.4.0 so it will end up pulling down 0.4.5. The problem is that istanbul has a dependency on esprima and esprima doesn't yet seem to support async/await.

[kevinludwig]

for what its worth, I tried upgrading esprima to 4.0.0-dev (the istanbul dependency) which is currently whats on master in github (for esprima), and the problem persists.

[kevinludwig]

Welp, node 7.6 landed and async/await is no longer behind a harmony flag, but I still can't get coverage for async/await.

[patrikx3]

yep, async/await is not working :( i think it is the last important language update for a while.

[thetutlage]

Install 1.1.0-alpha.1 from npm and it works. Just did a minute ago

npm i --save-dev [email protected]

[patrikx3]

works! thanks!

[magicdawn]

use npm i istanbul@next --save-dev, not @latest

[gbahamondezc]

Works, perfect with alpha version.

[kevinludwig]

what would you recommend as the way to get gulp-istanbul working? I have this vague feeling that if I make a PR to that repo saying "just use the alpha version of istanbul" I will get rejected.

[kevinludwig]

also if I just do cd node_modules/gulp-istanbul && npm install istanbul@next, then run a npm test for my project, it blows up inside of gulp-istanbul code, this is the complaint:

    var instrumenter = new opts.instrumenter(fileOpts);
                       ^
TypeError: opts.instrumenter is not a constructor

So did the interface change for istanbul in a way that would break gulp-istanbul?

[kevinludwig]

It's trying to do new istanbul.Instrumenter(fileOpts) just to make that a bit more clear.

[kevinludwig]

@gotwarlost
So I've realized that the API has pretty drastically changed between 0.4.5 and 1.1.0-alpha.1, which is why gulp-istanbul is not a trivial version bump upgrade. I'd be willing to give it a shot changing gulp-istanbul to work with istanbul@next but the docs don't seem to be updated at last on the README for the 1.1.0-alpha.1 tag. What are the chances that the README will be updated any time soon to reflect the new API?

[ovaar]

Is there any improvements on this issue?

[electerious]

From the readme:

Deprecation Notice: this version of istanbul is deprecated, we will not be landing pull requests or releasing new versions. But don't worry, the Istanbul 2.0 API is now available and is being actively developed in the new istanbuljs organization.

async/await is supported by default in the new version: https://github.com/istanbuljs/istanbuljs

Took me a while to realize that there's a difference between istanbul and istanbuljs on npm.

[bforbis]

A few questions:

Is istanbul v1.1.0-alpha.1 going to be released as a standard release? I understand that this package is considered deprecated in favor of what is available at https://istanbul.js.org using nyc, but it seems like upgrading to nyc is not necessarily trivial. To get async/await support using nyc, you have to involve babel. Now that async/await is part of the LTS release of node, I'd rather not involve babel into my project if I can avoid it.

[kevinludwig]

Nyc does not require banel with latest node. Its vastly simpler than the gulp plugin.

[bforbis]

Oh, looks like I misunderstood the istanbul website which wasn't clear on whether babel-plugin-istanbul was required. @kevinludwig is correct, this is not required.

[bennycode]

I also had problems using async and await calls in my jasmine tests. Updated istanbul from "0.4.5" to "1.1.0-alpha.1" and it works now like a charm! ✨

Here is my npm "coverage" script:

"coverage": "rimraf coverage && cross-env NODE_ENV=test istanbul cover --report html ./node_modules/jasmine/bin/jasmine.js"