Jest tests won't work without babel

Version

3.0.0-rc.10

Node and OS info

Node 10.7.0 / npm 6.3.0-next.0 / Windows 10

Steps to reproduce

1. Create new project with only Jest plugin selected
2. Run npm run test:unit

What is expected?

 PASS  tests/unit/HelloWorld.spec.js
  HelloWorld.vue
    √ renders props.msg when passed (22ms)

What is actually happening?

 FAIL  tests/unit/HelloWorld.spec.js
  ● Test suite failed to run

    Jest encountered an unexpected token

    This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.

    By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".
    Details:

    C:\node_workspace\test\tests\unit\HelloWorld.spec.js:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){import { shallowMount } from '@vue/test-utils';
                                                                                                ^

    SyntaxError: Unexpected token {

      at ScriptTransformer._transformAndBuildScript (node_modules/jest-runtime/build/script_transformer.js:403:17)

---

It works as expected if I install both Babel and Jest.

[ianchanning]

Many thanks @Mourdraug!

This finally solved my Jest + ES6 without babel problems (for an unrelated project), I’ll add my simplified solution to this.

I eventually understood by staring at commit 65d5d36d from the jestPlugin.spec.js, this adds the babel and a babel plugin as dependencies, not as devDependencies.

I have a completely unrelated project. But as is pointed out here Jest uses node so Jest needs to use babel even if your project doesn’t. So for a project which hasn’t installed babel yet, you still need to install babel, but as a regular dependency:

npm install babel-jest babel-plugin-transform-es2015-modules-commonjs

Then I modified my package.json to include:

  "babel": {
    "plugins": ["transform-es2015-modules-commonjs"]
  },

Now npm test runs without the import error. Here I don’t need a .babelrc file.

[Mourdraug]

My motivation for opting out babel is actually quite simple. I’d like to use ES6 without transpiling code to ES5 I don’t really use babel tho, so I’m not sure if it’s possible to configure it to handle imports and leave rest as is.