Babel 7 setup 'was loaded with "6.26.3"'

🐛 Bug Report

The setup suggested in the documentation doesn’t seem to work and triggers the following error message:

$ jest
 FAIL  ./hi.test.js
  ● Test suite failed to run

    Requires Babel "^7.0.0-0", but was loaded with "6.26.3". If you are sure you have a compatible version of @babel/core, it is likely that something in your build process is loading the wrong version. Inspect the stack trace of this error to look for the first entry that doesn't mention "@babel/core" or "babel-core" to see what is calling Babel. (While processing preset: "/Users/verekia/Local/Code/minimal-jest-babel-7/node_modules/@babel/preset-env/lib/index.js")

      at throwVersionError (node_modules/@babel/helper-plugin-utils/lib/index.js:65:11)
          at Array.map (<anonymous>)

(inline): Requires Babel “^7.0.0-0”, but was loaded with “6.26.3”. If you are sure you have a compatible version of @babel/core, it is likely that something in your build process is loading the wrong version. Inspect the stack trace of this error to look for the first entry that doesn’t mention “@babel/core” or “babel-core” to see what is calling Babel. (While processing preset: “/Users/verekia/Local/Code/minimal-jest-babel-7/node_modules/@babel/preset-env/lib/index.js”)

To Reproduce

The package.json used is the following:

{
  "name": "minimal-jest-babel-7",
  "version": "1.0.0",
  "license": "MIT",
  "scripts": {
    "start": "babel-node consumer.js",
    "test": "jest"
  },
  "babel": {
    "presets": [
      "@babel/preset-env"
    ]
  },
  "devDependencies": {
    "@babel/core": "^7.0.0-beta.52",
    "@babel/node": "^7.0.0-beta.52",
    "@babel/preset-env": "^7.0.0-beta.52",
    "babel-core": "^7.0.0-0",
    "jest": "^23.3.0"
  }
}

Expected behavior

Running jest should be able to run the test, which includes an import statement. The babel-node command of the minimal repo executes the import successfully.

Link to repl or repo (highly encouraged)

Here is a minimal repo: https://github.com/verekia/minimal-jest-babel-7

Run npx envinfo --preset jest

Paste the results here:

  System:
    OS: macOS High Sierra 10.13.5
    CPU: x64 Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz
  Binaries:
    Node: 10.1.0 - /usr/local/bin/node
    Yarn: 1.7.0 - ~/.yarn/bin/yarn
    npm: 5.6.0 - /usr/local/bin/npm
  npmPackages:
    jest: ^23.3.0 => 23.3.0 

[SimenB]

The docs says to install babel-jest 'babel-core@^7.0.0-0' @babel/core regenerator-runtime (https://jestjs.io/docs/en/getting-started#using-babel). Doing that (adding babel-jest) makes your reproduction pass.

(note that regenerator runtime is not needed, I honestly don’t remember in which cases it is)

[ruslanxdev]

I fix this problem with them.

npm i -D jest babel-jest babel-core@^7.0.0-bridge.0 @babel/core regenerator-runtime

// babel.config.js
'use strict';

module.exports = {
  presets: [
    '@babel/preset-env',
    '@babel/preset-react'
  ],
  plugins: [
    '@babel/plugin-transform-modules-commonjs',
    '@babel/plugin-transform-object-assign',
    '@babel/plugin-proposal-class-properties',
    '@babel/plugin-proposal-object-rest-spread'
  ]
};

// jest.config.js
'use strict';

module.exports = {
    transform: {
        '^.+\\.jsx$': 'babel-jest',
        '^.+\\.js$': 'babel-jest'
    }
};