SyntaxError: Cannot use import statement outside a module

[caesaneer]

When you use ECMAScript Modules in Node (v13.6.0 for me) combined with Jest, the following error occurs:

SyntaxError: Cannot use import statement outside a module

      at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:537:17)
      at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)

Here is the test code I am trying to execute.

import { checks } from '../../../../src/utils/index.js'

describe('Array type check', () => {
    test('to return false when not an array', () => {
        expect(checks.array('string')).toEqual(false)
    })
})

I suspect the issue is Jest is not configured to run Node code using "type: module" (ECMAScript Modules).

[ziishaned]

I resolved the issue by doing the following:

yarn add ts-jest -D

then in your jest.config.js file put following:

module.exports = {
  transform: {
    '^.+\\.ts?$': 'ts-jest',
  },
};

[SimenB]

Correct, ESM is not supported. You can track #4842. In the meantime, you need to transpile to cjs (using babel, typescript, etc)

EDIT: Since this issue is still getting traffic, please see https://jestjs.io/docs/en/ecmascript-modules

[smpeters]

A more complete set of steps is:

1. npm i --save-dev jest babel-jest @babel/preset-env
2. add the follow to the module.exports in your jest.config.js

transform: {
    "^.+\\.jsx?$": "babel-jest"
  },

3. create a babel.config.json file with the following

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

After this, I was able to get files with imports working just fine.

I had the same problem when I started to used babel... But later, I had a solution... I haven't had the problem anymore so far... Currently, Node v12.14.1, "@babel/node": "^7.8.4", I use babel-node and nodemon to execute (node is fine as well..)

package.json:
"start": "nodemon --exec babel-node server.js "debug": "babel-node debug server.js" !!note: server.js is my entry file, you can use yours.

launch.json:
When you debug, you also need to config your launch.json file "runtimeExecutable": "${workspaceRoot}/node_modules/.bin/babel-node" !!note: plus runtimeExecutable into the configuration.

Of course, with babel-node, you also normally need and edit another file, such as babel.config.js/.babelrc file

[genechan]

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

Awsome workaround!!

FYI for some people, if you are using a .babelrc the changes didn't work for me. I had to delete my .babelrc it and just use the suggested babel.config.json

[davetron5000]

@smpeters solution worked for me, but I want to see if I can explain exactly why it worked, because TBH I have no idea what those steps actually do (but thank you @smpeters for posting them!)

1. Jest has a transform option that takes an object where the keys are regular expressions of filenames to match and their values are how to transform them.
2. Jest calls these values a "path to transformer". I have no idea what this exactly means, but my best guess is that since we had to install the babel-jest module, "babel-jest" is a path to that module. So I guess if the module were called babel-jest-hooray then the "path to transformer" would be the string "babel-jest-hooray".
3. So what is the babel-jest module? Seems like it exists to use Babel to transform jest files, i.e. to solve this exact problem. If my supposition above is correct, then this is what it is: https://github.com/facebook/jest/blob/master/packages/babel-jest/src/index.ts#L163
4. OK, cool. So what is babel? It is a JavaScript Compiler (but so is Webpack? I dunno, let's go with it). It does the work. babel-jest is a glue between Babel—which doesn't know about Jest—and Jest.
5. To make babel work you need to configure it. It comes with presets, but these are not actually pre-set. You have to set them. Thus the @babel/preset-env module is installed.
6. What is the @babel/preset-env module? It is "a smart preset that allows you to use the latest JavaScript without needing to micromanage which syntax transforms", which basically means it sets all the defaults you want to do normal and unsurprising things. Nice!
7. So how does babel know how to use this? You have to tell it by creating that babel config file. That's where the "preset" configuration option comes in.

Whew!

[changyeamoon]

@smpeters I'm getting a ReferenceError: regeneratorRuntime is not defined and it points to a async await function as the culprit.

Any ideas about this?