Babel7 Jest unexpected token export

Question

I am having issues in running jest tests in my project with Babel7. Tests used to transpile perfectly with babel6. It also compiles perfectly with webpack with Babel7 but fails to run tests with jest due to a transpilation error. What am I doing wrong?

react/node_modules/generic-redux-root/index.js:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){export * from './source/CreateReduxRoot';
                                                                                         ^^^^^^

SyntaxError: Unexpected token export

my jest config

{
"unmockedModulePathPatterns": [
  "<rootDir>/node_modules/react",
  "<rootDir>/node_modules/react-dom",
  "<rootDir>/node_modules/react-addons-test-utils",
  "<rootDir>/node_modules/fbjs",
  "enzyme"
],
"roots": [
  "<rootDir>/__tests__"
],
"transformIgnorePatterns": [
  "node_modules/(^generic-)/i", //a module matching this is throwing an error
  "node_modules/react-infinite-scroller"
],
"setupFiles": [
  "./jestsetup.js"
],
"snapshotSerializers": [
  "enzyme-to-json/serializer"
],
"testResultsProcessor": "./jestTrxProcessor",
"verbose": true

}

My .babelrc

{
"presets": [
    [
        "@babel/preset-env",
        {
            "targets": {
                "ie": 11
            },
            "useBuiltIns": "usage"
        }
    ],
    "@babel/preset-react"
],
"plugins": [
    "@babel/plugin-transform-runtime",
    "@babel/plugin-syntax-dynamic-import",
    "@babel/plugin-syntax-import-meta",
    "@babel/plugin-proposal-class-properties",
    "@babel/plugin-proposal-json-strings",
    [
        "@babel/plugin-proposal-decorators",
        {
            "legacy": true
        }
    ],
    "@babel/plugin-proposal-function-sent",
    "@babel/plugin-proposal-export-namespace-from",
    "@babel/plugin-proposal-numeric-separator",
    "@babel/plugin-proposal-throw-expressions",
    "@babel/plugin-proposal-object-rest-spread",
    "@babel/plugin-transform-object-assign"
]

}

What am I doing wrong?

Answer 1

This is happening because Babel 7 no longer loads your .babelrc automatically. There is a new concept of root config which should be located in the root of your project and the file must be named babel.config.js and export an object.

So to give you some steps to follow:

1. rename your .babelrc to babel.config.js and make sure you use module.exports = {...}
2. run jest --clearCache to clear Jest internal cache (which costed me a few hours of banging my head against the wall)
3. At this point your babel config should be loaded correctly by Jest