Test suite failed to run, Jest encountered an unexpected token

[JaapSingh]

Hey everyone,

I recently imported the @FluentUI\react-charting module into my UX code so I could create a sparkline chart, and everything compiles and renders correctly.

However, I added a snapshot test and when I tried to generate a snapshot via "yarn test -u", I get the following error:

● 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".     
Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/en/ecmascript-modules for how to enable it.
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.     

You'll find more details and examples of these config options in the docs:https://jestjs.io/docs/en/configuration.html     
Details:     C:\...\src\Extension\Client\ReactViews\node_modules\@fluentui\react-charting\node_modules\d3-scale\src\index.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){export {
                                                                                             ^^^^^^     SyntaxError: Unexpected token 'export'       at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1350:14)
      at Object.<anonymous> (node_modules/@fluentui/react-charting/lib-commonjs/src/utilities/utilities.ts:3:1) Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        140.531 s
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

I did some research and I think it might be because Node.js cannot handle ES6 modules, and the way to get around this is to ensure that we compile files in the node_modules. I then confirmed that transformIgnorePatterns: ["node_modules/(?!@fluentui)"] is present in my jest.config.js file

Does anyone have any ideas as to what I can try to get these snapshot tests to work?

[AtishayMsft]

@JaapSingh Looks like you are having troubles using the v4 for d3-scale which is an ES6 module.
Can you try adding a moduleNameMapper in your jest.config.js file like it has been done in the charting package. https://github.com/microsoft/fluentui/blob/master/packages/react-charting/jest.config.js