Unexpected token 'export'

[websocket98765]

I encountered the same error that we saw on the sandbox again. This time when running a Jest test that shallow renders my main <App /> component using Enzyme:

It seems to be triggered by using import { useRouter } from 'react-router-ts';, since this line is pointed out in the error message. That's also about when we saw the error on the sandbox too, after it was updated to use that.

/node_modules/react-router-ts/dist/index.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest)
    {export * from "./basename";                 
     ^^^^^^
    SyntaxError: Unexpected token 'export'

    > 
    > 19 | import { useRouter } from 'react-router-ts';
    > 
    
    at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:537:17)
    at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)
    at Object.<anonymous> (src/components/App.jsx:19:1)

Possibly an issue with the build script not compiling the ./basename file?

Interestingly, my app runs fine. Only my tests causes the error.

[Lusito]

This library is shipped as es2015 modules. jest doesn't support this natively yet, see these topics for various workarounds:
nrwl/nx#812 (comment)
jestjs/jest#4842
jestjs/jest#2081

I've used the first one successfully. I.e. change your jest.config.js to this:

const esModules = ['react-router-ts'].join('|');
// ...
module.exports = {
  //...
    transformIgnorePatterns: [`/node_modules/(?!${esModules})`],
  // ...
};

I thought about providing an additional commonjs build to avoid these kind of issues in outdated tools, but I didn't get to do the research yet.

[websocket98765]

Thanks for the info. Hopefully Jest gets this updated eventually. I experimented with the suggestion & others, but it gets more complicated once other layers like create-react-app and react-app-rewired are involved, given both alter Babel and Jest behavior. Decided it's not a big deal and just skipping tests for my the App component to keep making progress.