Jest: babel-jest plugin & babel 7 incompatibility

[alechp]

Do you want to request a _feature_ or report a _bug_?
Bug

What is the current behavior?
babel-7-jest does work for me.
babel-jest does _not_ work for me.

If the current behavior is a bug, please provide the steps to reproduce and
either a repl.it demo through https://repl.it/languages/jest or a minimal
repository on GitHub that we can yarn install and yarn test.

What is the expected behavior?
When I run test suite using babel-7-jest:

When I run test suite using babel-jest:

 TypeError: Cannot read property 'loose' of undefined (While processing preset: "/Users/alechp/Code/servexyz/repospace/cli/node_modules/@babel/preset-env/lib/index.js")

All that is required to make these tests pass is toggle the "transform" option in Jest config from "babel-jest" to "babel-7-jest" (note: I have both installed right now for easy swapping, but I have tried executing babel-jest after having removed babel-7-jest from dependencies and clearing cache)

Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.

Relevant dependencies, jest configuration and babel configuration

"devDependencies": {
    "@babel/core": "^7.0.0-beta.39",
    "@babel/node": "^7.0.0-beta.39",
    "@babel/preset-env": "^7.0.0-beta.39",
    "babel-7-jest": "^21.3.3",
    "babel-jest": "^22.2.2",
    "jest": "^22.2.2"
  },
  "jest": {
    "verbose": true,
    "bail": false,
    "collectCoverage": false,
    "modulePathIgnorePatterns": ["sandbox", "node_modules"],
    "transform": {
      "^.+\\.jsx?$": "babel-jest"
    }
  },
  "babel": {
    "presets": [
      [
        "@babel/preset-env",
        {
          "targets": {
            "node": "9.3.0"
          }
        }
      ]
    ]
  }

[thymikee]

See the docs on using Jest with Babel 7: https://facebook.github.io/jest/docs/en/getting-started.html#using-babel

[alechp]

Package usage isn't up to date with repo

Getting Started * Jest

npm/babel-jest does not include this warning:

(To save you the click, there's no overflow on the MD block either; it truncates after @babel/core)

Note: If you are using babel version 7 you have to install babel-jest with
npm install --save-dev babel-jest babel-core@^7.0.0-0 @babel/core

---

This still doesn't resolve my issue, but sharing because it might create issues for others who are using old versions NPM instead of Yarn.

[thymikee]

Feel free to send a PR with the note. However we don't actively support npm 2.
Also, if the official installation doesn't work on you, send a repo link which shows that, along with tools version you use (e.g. npm).

[alechp]

Okay. Check this out: babel-jest-comparison

[SimenB]

@alechp you haven't installed babel-core@^7.0.0-0 which is in the linked documentation.

This diff makes your tests green:

diff --git i/babel-jest/package.json w/babel-jest/package.json
index 397a4eb..5965a04 100644
--- i/babel-jest/package.json
+++ w/babel-jest/package.json
@@ -9,6 +9,7 @@
     "@babel/core": "^7.0.0-beta.39",
     "@babel/node": "^7.0.0-beta.39",
     "@babel/preset-env": "^7.0.0-beta.39",
+    "babel-core": "^7.0.0-0",
     "babel-jest": "^22.2.2",
     "jest": "^22.2.2"
   },
diff --git i/babel-jest/yarn.lock w/babel-jest/yarn.lock
index fcb51ec..096bf57 100644
--- i/babel-jest/yarn.lock
+++ w/babel-jest/yarn.lock
@@ -664,6 +664,10 @@ babel-core@^6.0.0, babel-core@^6.26.0:
     slash "^1.0.0"
     source-map "^0.5.6"

+babel-core@^7.0.0-0:
+  version "7.0.0-bridge.0"
+  resolved "https://registry.yarnpkg.com/babel-core/-/babel-core-7.0.0-bridge.0.tgz#95a492ddd90f9b4e9a4a1da14eb335b87b634ece"
+
 babel-generator@^6.18.0, babel-generator@^6.26.0:
   version "6.26.1"
   resolved "https://registry.yarnpkg.com/babel-generator/-/babel-generator-6.26.1.tgz#1844408d3b8f0d35a404ea7ac180f087a601bd90"

[alechp]

@SimenB I have to install both @babel/core & babel-core ?

[rickhanlonii]

Correct, see https://github.com/facebook/jest/pull/4557

Notice that babel-core and @babel/core are in both the package usage and the repo

[alechp]

I see. Thanks for clarifying, @rickhanlonii

I'll stick with babel-7-jest in the meantime.

[xlijun]

On Windows
npm install --save-dev babel-jest babel-core@^7.0.0-0 @babel/core
fails. Have to use babel-core@^7.0.0-bridge.0 instead.

[wmertens]

So I installed babel-core@bridge and I still get babel-core from jest-config and jest-runtime:

$ npm ls babel-core
[email protected] /path/proj
├── [email protected]
└─┬ [email protected]
  ├─┬ [email protected]
  │ └─┬ [email protected]
  │   └─┬ [email protected]
  │     └── [email protected]
  └─┬ [email protected]
    └── [email protected]

maybe -config and -runtime should declare babel-core as a peerDependency?

[DanielJoyce]

Same issue. Jest is leading to mixed babel version installs.

[DBosley]

Not sure why this issue was closed, but here's an open issue for the same problem: #6913