Tests fail with async

Not completely sure this is an issue of this repo, could be a jest's one. I'm reporting it here because it could be a configuration problem.

Description

Running npm test fails when using async/await.

Expected behavior

The test runs

Actual behavior

I receive an error:

  ● Test suite failed to run

    /src/merchants.js: Expected type "Expression" with option {}
      
      at Object.t.(anonymous function) [as assertExpression] (node_modules/babel-types/lib/index.js:362:13)
      at Array.forEach (native)

Environment

Run these commands in the project folder and fill in their results:

npm ls react-scripts: v0.8.1
node -v: v6.9.1
npm -v: v3.10.8
Operating system: Fedora 24
Browser and version: --

Reproducible Demo

Just a new "cra" project, with an async/await function tested.

I have a demonstration here, just git clone, npm install and npm test.

The problem seems to be caused by some interaction between the return value of an awaited function and destructuring it.

E.g.:

const getId = async () => {
  const p = await dispatch(42)
  return p.id
}

works, while

const getId = async () => {
  const { id } = await dispatch(42)
  return id
}

or

const getId = async () => {
  const p = await dispatch(42)
  const { id } = p
  return id
}

don't work.

In facts, tapping into node_modules/babel-generator/lib/buffer.js and casting the argument str to a String, I get an error that looks like:

var p, null;return _regenerator2.default.wrap
       ^^^^

Did it work before?

Yes, we're migrating a project from v0.6.1 to the latest

I'm getting a lot of "strange" errors.

Another one, for example, is that while using immutable, this won't work anymore:

const { Record } = require("immutable")

const User = new Record({ id: NaN })
new User({ id: 42 })

while it worked before (and works now, same version).

and the error is:

TypeError: _definition2.default is not a constructor

I was able to fix all the errors by reintroducing babel-preset-latest in the test env, so it might be some misconfiguration of babel-preset-env?

Also removing { targets: { node: 'current' } }, without reintroducing babel-preset-latest seems to make the deed.

Can you try:

Keeping -env usage like in master
But also reverting Enable babel parameters/destructuring for all versions of Node #927

?

If you mean like this:

// ...

const plugins = [

// ...

    // Polyfills the runtime needed for async/await and generators
    [require.resolve('babel-plugin-transform-runtime'), {
      helpers: false,
      polyfill: false,
      regenerator: true,
      // Resolve the Babel runtime relative to the config.
      moduleName: path.dirname(require.resolve('babel-runtime/package'))
    }],
    // The following two plugins are currently necessary to get
    // babel-preset-env to work with rest/spread. More info here:
    // https://github.com/babel/babel-preset-env#caveats
    // https://github.com/babel/babel/issues/4074
    // const { a, ...z } = obj;
    require.resolve('babel-plugin-transform-es2015-destructuring'),
    // const fn = ({ a, ...otherProps }) => otherProps;
    require.resolve('babel-plugin-transform-es2015-parameters')
  ];

// ...

if (env === 'test') {
  module.exports = {
    presets: [
      // ES features necessary for user's Node version
      [require('babel-preset-env').default, {
        targets: {
          node: 'current',
        },
      }],

// ...

no, unfortunately it doesn't work (I always double-check it by reintroducing babel-preset-latest at the end)

@hzoo

@hzoo Any ideas?

The result I get from babel-preset-env is that I need:


check-es2015-constants: false
syntax-trailing-function-commas: true
transform-async-to-generator: true
transform-es2015-arrow-functions: false
transform-es2015-block-scoped-functions: false
transform-es2015-block-scoping: false
transform-es2015-classes: false
transform-es2015-computed-properties: false
transform-es2015-destructuring: false
transform-es2015-for-of: false
transform-es2015-function-name: false
transform-es2015-literals: false
transform-es2015-object-super: false
transform-es2015-parameters: false
transform-es2015-shorthand-properties: false
transform-es2015-spread: false
transform-es2015-sticky-regex: false
transform-es2015-template-literals: false
transform-es2015-typeof-symbol: false
transform-es2015-unicode-regex: false
transform-exponentiation-operator: true
transform-regenerator: false

I'll try to reintroduce them one by one..

Thanks for your help debugging this.

No worries ^_^

Apparently what I need are:

transform-es2015-arrow-functions

unknown Expression of type "ArrowFunctionExpression"

transform-es2015-destructuring

Expected type "Expression" with option {}

transform-es2015-parameters

var addIndex = function addIndex({ index, ...routes } = {}, base)
                                          ^^^
    SyntaxError: Unexpected token ...

so yeah, the two you were saying before, plus () => {}.

Although we use es6+ a lot, and we have approx 230 unit tests, I have to say that these could be only our needs, and others might need more plugins..

So these are likely Babel bugs about hidden plugin dependencies? Can you reduce each to an isolated Babel bug report?

Either that, or some bug in babel-plugin-env, I'm going to investigate further tomorrow.

In either case should I make a PR reverting to using babel-plugin-latest for the moment?

I won't be able to cut a release today anyway so might as well wait for more details (or investigate myself tomorrow if I get there first). Once we know more we'll decide and cut a release.

Seems reasonable

@EnoahNetzach

@EnoahNetzach I'll try and take a look at this later tonight as well

It seems that babel-plugin-transform-regenerator tries to assert that an ObjectPattern is of type Expression.

I think that definitely we should ask help from @kittens?

btw, this seems to be already issued on babel, maybe I'll continue the conversation there.

Is this issue underlying for all the problems listed here?

Not entirely sure, I checked only transform-es2015-destructuring for now

I'm closing this issue in favor to #1156

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EnoahNetzach commented on Dec 5, 2016

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Tests fail with `async` #1160