43

I am trying to write a javascript test in intellij for which I need to import some dependancies and I want to use ES6 style import statements but getting error

/usr/local/bin/node /workspace/rr-sample/node_modules/mocha/bin/_mocha
--ui bdd --reporter "/Users/me/Library/Application Support/IntelliJIdea2019.1/NodeJS/js/mocha-intellij/lib/mochaIntellijReporter.js"
tests/*.test.js /workspace/rr-sample/tests/App.test.js:3
import chai from 'chai'
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at wrapSafe (internal/modules/cjs/loader.js:1043:16)
    at Module._compile (internal/modules/cjs/loader.js:1091:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1160:10)
    at Module.load (internal/modules/cjs/loader.js:976:32)
    at Function.Module._load (internal/modules/cjs/loader.js:884:14)
    at Module.require (internal/modules/cjs/loader.js:1016:19)
    at require (internal/modules/cjs/helpers.js:69:18)
    at /workspace/rr-sample/node_modules/mocha/lib/mocha.js:334:36
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (/workspace/rr-sample/node_modules/mocha/lib/mocha.js:331:14)
    at Mocha.run (/workspace/rr-sample/node_modules/mocha/lib/mocha.js:809:10)
    at Object.exports.singleRun (/workspace/rr-sample/node_modules/mocha/lib/cli/run-helpers.js:108:16)
    at exports.runMocha (/workspace/rr-sample/node_modules/mocha/lib/cli/run-helpers.js:142:13)
    at Object.exports.handler (/workspace/rr-sample/node_modules/mocha/lib/cli/run.js:292:3)
    at Object.runCommand (/workspace/rr-sample/node_modules/yargs/lib/command.js:242:26)
    at Object.parseArgs [as _parseArgs] (/workspace/rr-sample/node_modules/yargs/yargs.js:1087:28)
    at Object.parse (/workspace/rr-sample/node_modules/yargs/yargs.js:566:25)
    at Object.exports.main (/workspace/rr-sample/node_modules/mocha/lib/cli/cli.js:68:6)
    at Object.<anonymous> (/workspace/rr-sample/node_modules/mocha/bin/_mocha:10:23)
    at Module._compile (internal/modules/cjs/loader.js:1121:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1160:10)
    at Module.load (internal/modules/cjs/loader.js:976:32)
    at Function.Module._load (internal/modules/cjs/loader.js:884:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:67:12)
    at internal/main/run_main_module.js:17:47

What exactly is the issue? I found this link (and others) http://xahlee.info/js/js_import_export.html which tells you how to fix this error but in another context which doesn't help me, and it doesn't explain what the problem is.

In case it is helpful here is the code I am using.

//const chai = require("chai");
import chai from 'chai'

const React = require("react");
const expect = chai.expect;

describe('how it works first-time test', () => {
  it('checks equality', () => {

    const val = false;
    expect(val).to.be.false;
  });

});
vsync
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driftwood
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    _“it doesn't explain what the problem is”_ — it does explicitly say _“If your code uses `import` or `export`, then it must be loaded as module.”_ along the part where it says that you must use `type="module"`. Have you seen [Intellij Idea Ecmascript Harmony modules syntax](https://stackoverflow.com/q/21609025/4642212)? – Sebastian Simon Nov 26 '19 at 02:19

6 Answers6

27

The easiest way to run Mocha tests written in ES6 is compiling them on-the-fly using Mocha --require @babel/register option (see https://github.com/mochajs/mocha/wiki/compilers-deprecation#what-should-i-use-instead-then). Of course, you need to make sure to install the corresponding modules and set up the .babelrc accordingly

package.json:

"dependencies": {
  "@babel/cli": "^7.7.4",
  "@babel/core": "^7.7.4",
  "@babel/preset-env": "^7.7.4",
  "@babel/register": "^7.7.4",
...
}

.babelrc:

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

enter image description here

See also https://dev.to/bnorbertjs/my-nodejs-setup-mocha--chai-babel7-es6-43ei

lena
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23

I had the same problem when updating one of my ts libraries to es6 modules instead of commonjs. After the change in the tsconfig.json my npm run test produced the mentioned error.

import chai from 'chai'
^^^^^^
SyntaxError: Cannot use import statement outside a module

I solved it without babel by adding an own tsconfig file just for testing.

tsconfig.testing.json

{
  "compilerOptions": {
      "module": "commonjs",
      "target": "es6"
  },
  "include": ["**/*.spec.ts"]
}

To run the tests via script in package.json

"test": "cross-env TS_NODE_PROJECT=\"tsconfig.testing.json\" mocha -r ts-node/register src/**/*.spec.ts",

(cross-env to set the env variable os independent)

andymel
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    Note that `cross-env` is in maintenance mode – pixel Feb 15 '21 at 08:36
  • @pixel, can you please add how this is relevant, thank you – andymel Feb 15 '21 at 09:02
  • some people might want to stick to up to date / actively maintained libs - my comment was intended for those people – pixel Feb 15 '21 at 10:16
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    Maintenance mode basically means no new features will be added, just bugfixes if necessary. It stays relevant for the usecase above. See more info and find alternatives at https://github.com/kentcdodds/cross-env/issues/257 – andymel Feb 15 '21 at 10:55
  • Did it not work without the tsconfig change? I just had the same issue and this script corrected it without any additional changes: "test": "mocha -r ts-node src/**/*.test.ts" – bmd Apr 28 '21 at 20:10
  • cross-env is only needed if you're running Windows. – java-addict301 Sep 09 '21 at 02:54
  • cross-env can be a solution if ANYONE, working on the project, is running windows – andymel Nov 14 '22 at 09:14
9

I was able to get this working by adding a .mocharc.yaml file at the source of my project with the following:

require: '@babel/register'

source: https://github.com/mochajs/mocha-examples/tree/master/packages/babel

Devin Clark
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  • This was enough for me to be able to run in webstorm by right clicking on `it` and `describe` – blak3r Oct 05 '21 at 01:00
  • This solved issue of `import` but now having another issue of test coverage dropped from 97% to 10% – Ashish Kamble Jun 15 '22 at 07:08
  • @Ashish Kamble If you don't import any file you'll have full coverage. It's like if you don't write any code you won't have any bugs – Viraj Singh Sep 08 '22 at 12:16
2

The cause of my issue was - an old version of Mocha, in fact any <6.0.0, even when the 'require: @babel/register' was configured. I updated Mocha to 9.0.0, I also updated Babel libraries to the latest and the problem was solved.

As it is also suggested in the Mocha docs, use config file, like '.mocharc.js', where you have to declare required Babel dependancy like in this example:

.mocharc.js

module.exports = {
  ...
  require: '@babel/register',
  ...
}

package.json

{
  ...
  "devDependencies": {
    "@babel/core": "^7.9.0",
    "@babel/preset-env": "^7.3.4",
    "@babel/preset-react": "7.18.6",
    "@babel/register": "^7.9.0"
    ...
    "mocha": "^9.0.0",
  }
}
technik
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0

According to the doc:

https://nodejs.org/api/esm.html#esm_code_import_code_statements

So you have to ensure execute the script as an es module.

e.g. Execute the script using babel-node instead of Nodejs to enable the es6 or newer.

Pengson
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0

enter image description here

For me, I was not able to run it via inline debug option in intellj. So I set extra mocha option and this solved the issue.

--compilers js:babel-core/register

Also, to run via terminal

npx mocha  --compilers js:babel-core/register
NIKHIL C M
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