chpio / babel-plugin-transform-async-to-bluebird Goto Github PK

Since async/await is transformed in to coroutine, you get an error when you await something that is not a promise, see: http://bluebirdjs.com/docs/error-explanations.html#error-a-value-was-yielded-that-could-not-be-treated-as-a-promise

For example

(async () => {
  await 1;
})();

should work without problems, as it does with the standard babel async-to-generator transform

Maybe it needs to transform await x to yield Promise.resolve(x)

I've experienced a strange bug while trying to use this plugin. I believe it is caused by the wrapping of async class methods twice (seems to stop the coroutine from running).

Here is a sample code snippet that reproduces the bug:

class Test {
  async go () {
    console.log('start:go')
    await Promise.resolve('test')
    console.log('end:go')
  }
}

const runGo = () => {
  return (new Test()).go()
}

;(async () => {
  console.log('start:all')
  await runGo()
  console.log('end:all')
})()

If you transpile this using the bluebird preset (which relies on this plugin) and the transform-es2015-modules-commonjs plugin, the resultant code is this:

'use strict';

var _bluebird = require('bluebird');

class Test {
  *go() {
    return (0, _bluebird.coroutine)(function* () {
      console.log('start:go');
      yield (0, _bluebird.resolve)((0, _bluebird.resolve)('test'));
      console.log('end:go');
    })();
  }
}

const runGo = () => {
  return new Test().go();
};

(0, _bluebird.coroutine)(function* () {
  console.log('start:all');
  yield (0, _bluebird.resolve)(runGo());
  console.log('end:all');
})();

Running this showing the promise never running:

start:all
end:all

If I simply remove the * from the go class method in the transpiled output (and therefore just undo its generatorness - and let it return the coroutine generator instead), this issue goes away and the result is:

start:all
start:go
end:go
end:all

Are there any plans to release a beta version of this plugin that works with babel 7?