jest (babel) fails if using ES6 imports

Environment

devDependencies:

"@haul-bundler/babel-preset-react-native": "^0.13.2",
"@haul-bundler/cli": "^0.13.1",
"@haul-bundler/preset-0.60": "^0.13.0",
"jest": "^24.9.0",

Node v12.4.0

Description

After changing babel.config.js preset @haul-bundler/babel-preset-react-native jest tests don’t support import syntax anymore. If switching back to metro-react-native-babel-preset jest works again.

Trying to figure out what setting is triggering this, but not expert in babel configuration.

Getting errors such as

    import fetch, { Headers } from 'node-fetch';
           ^^^^^

    SyntaxError: Unexpected identifier

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

[zamotany]

@jounii Looks a bit hacky, you can alternatively try this:

env: {
  test: {
    plugins: [['@babel/plugin-transform-modules-commonjs', { allowTopLevelThis: true }]]
  }
}

It should work for every file if it’s being run by Jest, which sets process.env.NODE_ENV to test.

[zamotany]

In next release of @haul-bundler/babel-preset-react-native CommonJS transform will be added automatically in when NODE_ENV === 'test', like above.