Handle config function return promise of config object array

[chenesan]

For #76 .
I've changed a little how startFarm and webpackWorker get config and added a test for config function return promise of config object array.
After the change, there are some tests get failed. And I'm not sure how to handle them. @pago @efegurkan I need some advices about them:

webpackWorker.spec.js

• webpackWorker › arguments › multi config options › should fail if expectedConfigLength > 1 in case of single config
• webpackWorker › arguments › multi config options › should fail if expectedConfigLength dont match with config.length

This two all expect Promise.reject will be called when call webpackWorker function. Before this change they will be called immediately. But since we have to get the config array after promise resolved,
I move the config length checking part into the then part, so they will not be called immediately and we cannot check the mock synchronously. I have tried checking calls asynchronously in test (webpackWorker.then(...)) but it seems that webpackWorker will not finish until jest test time out.

index.spec.js

• index.js › run › error callback › should log and reject with error
• index.js › run › then callback › should filter non-truthy and return results
• index.js › run › shutdownCallback › should call end and remove callback

The above three snapshot tests will lose one line "[WEBPACK] Building 1 target" since we have to move the console.log into promise(again now we have to resolve config function promise before we know its length). Not sure if it's ok to pass those snapshot tests.

[paales]

@chenesan Any updates on this?

[chenesan]

I may try to take a look again this week.

[coveralls]

Coverage decreased (-3.4%) to 83.524% when pulling 8d7df7b on chenesan:resolve-config-func-return-promise-of-array into 66da53e on trivago:master.

[chenesan]

@pago I just fixed the tests and it's ok to review it :-) You could also test it by manually create a minimal config file which is a function return promise of config array and run ./bin/run:

/* webpack.config.js */
var path = require('path');
module.exports = () => Promise.resolve([{
    entry: './pageA.js',
    output: {
        path: path.resolve(__dirname, './dist'),
        filename: 'pageA.bundle.js'
    }
}, {
    entry: './pageB.js',
    output: {
        path: path.resolve(__dirname, './dist'),
        filename: 'pageB.bundle.js'
    }
}]);

[pago]

Looks very good to me. Thank you for the time you put into building this feature!

@byara could you please also take a look? Then we can proceed with merging and releasing this feature. :)

[byara]

Thank you @chenesan, good work 👍
@pago It looks good to me :)

[chenesan]

Hi @pago and @byara sorry for pinging, anything I could do to help proceeding?

[pago]

Hi @chenesan , I'm sorry I didn't manage to take care of this before my vacation. I'll release it in a moment.

[pago]

Released as 2.4.0