Mocha 6, Babel 7, ES6: SyntaxError: Unexpected token export

Question

I'm trying to create a simple npm package based on another called 'sidebar-v2' (https://github.com/Turbo87/sidebar-v2)

For that reason, I've tried to update the JS code to ES6, however when I try to test if the updates are ok, the mocha raises an exception, that I send below:

> @rmmariano/[email protected] test /home/inpe/Documents/datainfo/npm_packages/ol-sb
> mocha --require @babel/register

/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/ol/control.js:5
export {default as Attribution} from './control/Attribution.js';
^^^^^^

SyntaxError: Unexpected token export
    at new Script (vm.js:85:7)
    at createScript (vm.js:266:10)
    at Object.runInThisContext (vm.js:314:10)
    at Module._compile (internal/modules/cjs/loader.js:698:28)
    at Module._compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:99:24)
    at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Object.newLoader [as .js] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Module.require (internal/modules/cjs/loader.js:667:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at Object.<anonymous> (/home/inpe/Documents/datainfo/npm_packages/ol-sb/src/ol3-sidebar.js:1:1)
    at Module._compile (internal/modules/cjs/loader.js:738:30)
    at Module._compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:99:24)
    at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Object.newLoader [as .js] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Module.require (internal/modules/cjs/loader.js:667:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at Object.<anonymous> (/home/inpe/Documents/datainfo/npm_packages/ol-sb/src/index.js:1:1)
    at Module._compile (internal/modules/cjs/loader.js:738:30)
    at Module._compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:99:24)
    at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Object.newLoader [as .js] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Module.require (internal/modules/cjs/loader.js:667:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at Object.<anonymous> (/home/inpe/Documents/datainfo/npm_packages/ol-sb/test/test.js:4:1)
    at Module._compile (internal/modules/cjs/loader.js:738:30)
    at Module._compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:99:24)
    at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Object.newLoader [as .js] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Module.require (internal/modules/cjs/loader.js:667:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at /home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:327:36
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:324:14)
    at Mocha.run (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:801:10)
    at Object.exports.singleRun (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run-helpers.js:207:16)
    at exports.runMocha (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run-helpers.js:300:13)
    at Object.exports.handler.argv [as handler] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run.js:296:3)
    at Object.runCommand (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/lib/command.js:238:44)
    at Object.parseArgs [as _parseArgs] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:1089:24)
    at Object.parse (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:566:25)
    at Object.exports.main (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/cli.js:62:6)
    at Object.<anonymous> (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/bin/_mocha:10:23)
    at Module._compile (internal/modules/cjs/loader.js:738:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:801:12)
    at internal/main/run_main_module.js:21:11
npm ERR! Test failed.  See above for more details.

I've already tried to follow the answer of other questions on StackOverflow, such as:

• Babel unexpected token import when running mocha tests

• Unexpected token import, can not set up ES6 in my JS project with Mocha, Chai and Sinon

But no one of them worked to me, unfortunately.

When I try to update my .babelrc to:

{
    "presets": ["@babel/preset-env", "es2015"]
}

The error changes to:

> @rmmariano/[email protected] test /home/inpe/Documents/datainfo/npm_packages/ol-sb
> mocha --require @babel/register

/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:1148
      else throw err
           ^

Error: Cannot find module 'babel-preset-es2015' from '/home/inpe/Documents/datainfo/npm_packages/ol-sb'
    at Function.module.exports [as sync] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/resolve/lib/sync.js:58:15)
    at resolveStandardizedName (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/files/plugins.js:101:31)
    at resolvePreset (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/files/plugins.js:58:10)
    at loadPreset (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/files/plugins.js:77:20)
    at createDescriptor (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:154:9)
    at items.map (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:109:50)
    at Array.map (<anonymous>)
    at createDescriptors (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:109:29)
    at createPresetDescriptors (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:101:10)
    at presets (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:47:19)
    at mergeChainOpts (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-chain.js:320:26)
    at /home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-chain.js:283:7
    at buildRootChain (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-chain.js:120:22)
    at loadPrivatePartialConfig (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/partial.js:85:55)
    at loadFullConfig (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/full.js:43:39)
    at loadOptions (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/index.js:27:36)
    at OptionManager.init (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/index.js:231:36)
    at compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/register/lib/node.js:61:42)
    at compileHook (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/register/lib/node.js:102:12)
    at Module._compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:93:29)
    at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Object.newLoader [as .js] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Module.require (internal/modules/cjs/loader.js:667:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at /home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:327:36
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:324:14)
    at Mocha.run (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:801:10)
    at Object.exports.singleRun (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run-helpers.js:207:16)
    at exports.runMocha (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run-helpers.js:300:13)
    at Object.exports.handler.argv [as handler] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run.js:296:3)
    at Object.runCommand (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/lib/command.js:238:44)
    at Object.parseArgs [as _parseArgs] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:1089:24)
    at Object.parse (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:566:25)
    at Object.exports.main (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/cli.js:62:6)
    at Object.<anonymous> (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/bin/_mocha:10:23)
    at Module._compile (internal/modules/cjs/loader.js:738:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:801:12)
    at internal/main/run_main_module.js:21:11
npm ERR! Test failed.  See above for more details.

package.json

{
  ...
  "scripts": {
    "start": "nodemon --exec babel-node ./src/index.js",
    "test": "./node_modules/.bin/mocha --require @babel/register"
  },
  "devDependencies": {
    "@babel/cli": "^7.2.3",
    "@babel/core": "^7.3.4",
    "@babel/node": "^7.2.2",
    "@babel/preset-env": "^7.3.4",
    "@babel/register": "^7.0.0",
    "chai": "^4.2.0",
    "mocha": "^6.0.2",
    "nodemon": "^1.18.10"
  },
  "dependencies": {
    "ol": "^5.3.1"
  }
}

.babelrc

{
    "presets": ["@babel/preset-env"]
}

Could someone help me?

Source code can be found here: https://github.com/rmmariano/ol-sb

Edit 1:

I've tried to update my .babelrc to:

{
    "presets": ["@babel/preset-env", "es2015"]
}

And to install the package:

npm install -S babel-preset-es2015

But the following error starts to appear when I run "npm test":

> @rmmariano/[email protected] test /home/inpe/Documents/datainfo/npm_packages/ol-sb
> mocha --require @babel/register

/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:1148
      else throw err
           ^

Error: Plugin/Preset files are not allowed to export objects, only functions. In /home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/babel-preset-es2015/lib/index.js
    at createDescriptor (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:178:11)
    at items.map (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:109:50)
    at Array.map (<anonymous>)
    at createDescriptors (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:109:29)
    at createPresetDescriptors (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:101:10)
    at presets (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-descriptors.js:47:19)
    at mergeChainOpts (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-chain.js:320:26)
    at /home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-chain.js:283:7
    at buildRootChain (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/config-chain.js:120:22)
    at loadPrivatePartialConfig (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/partial.js:85:55)
    at loadFullConfig (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/full.js:43:39)
    at loadOptions (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/config/index.js:27:36)
    at OptionManager.init (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/core/lib/index.js:231:36)
    at compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/register/lib/node.js:61:42)
    at compileHook (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/@babel/register/lib/node.js:102:12)
    at Module._compile (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:93:29)
    at Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Object.newLoader [as .js] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Module.require (internal/modules/cjs/loader.js:667:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at /home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:327:36
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:324:14)
    at Mocha.run (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/mocha.js:801:10)
    at Object.exports.singleRun (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run-helpers.js:207:16)
    at exports.runMocha (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run-helpers.js:300:13)
    at Object.exports.handler.argv [as handler] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/run.js:296:3)
    at Object.runCommand (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/lib/command.js:238:44)
    at Object.parseArgs [as _parseArgs] (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:1089:24)
    at Object.parse (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:566:25)
    at Object.exports.main (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/lib/cli/cli.js:62:6)
    at Object.<anonymous> (/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/mocha/bin/_mocha:10:23)
    at Module._compile (internal/modules/cjs/loader.js:738:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:749:10)
    at Module.load (internal/modules/cjs/loader.js:630:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:570:12)
    at Function.Module._load (internal/modules/cjs/loader.js:562:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:801:12)
    at internal/main/run_main_module.js:21:11
npm ERR! Test failed.  See above for more details.

Edit 2:

I've tried to update my .babelrc to:

{
    "presets": ["@babel/preset-env", "@babel/preset-es2015"]
}

And to install the package:

npm install -S @babel/preset-es2015

But the following error starts to appear when I run "npm test":

> @rmmariano/[email protected] test /home/inpe/Documents/datainfo/npm_packages/ol-sb
> mocha --require @babel/register

/home/inpe/Documents/datainfo/npm_packages/ol-sb/node_modules/yargs/yargs.js:1148
      else throw err
           ^

Error: Cannot find module '@babel/preset-es2015' from '/home/inpe/Documents/datainfo/npm_packages/ol-sb'

Answer 1

Short solution. I had a similar problem with imports and exports.

Also, Babel did not work well with mocha version 7.2.0 and npm version 6.14.4. So I solved the problem using esm version 3.2.25.

npm install --save-dev esm 

My package.json is using this:

"scripts": {
  "test": "mocha -r esm --exit"
}