Transpilation Errors Using Modern Test

[bmoellers]

So I am running in to an issue that some of the modules at my company are not commonJS supported by Jest but modern using imports instead of require. However when I run these through modern test this results in an unexpected token.

● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • 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/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /Users/BMoellers/code/monorepo/node_modules/@abc/web-common-i18n/lib/index.js:5
    import I18nTranslations from './I18nTranslations';
    ^^^^^^

    SyntaxError: Cannot use import statement outside a module

    > 1 | import initI18n, { time, date, number, numberWithAbbr } from '@abc/web-common-i18n';
        | ^
      2 | import stringInterpolator from './localization/stringInterpolator';
      3 | import { getLocale } from './localization/translatedStrings';
      4 |

      at Runtime.createScriptFromCode (../../node_modules/jest-config/node_modules/jest-runtime/build/index.js:1505:14)
      at Object.require (src/lib/i18n/createI18n.ts:1:1)
      at Object.require (src/lib/i18n/__tests__/getServerRenderedTranslations.test.ts:3:1)

The most common solution is to run jest or react testing with --transformIgnorePatterns set to the module. However I don't see any support for this with modern test. I tried a jest.config.js file and a babel.config.js file to try and get anything to change but nothing has happened.

If I add testing.transform = 'ts-jest' it causes more errors in the tsx files during the react render so that is not going to help. I cannot quickly create a test reproduction at this time because I cannot share company code. Any ideas on how to fix this?

[bmoellers]

So you can add options to jest in modern.config.js.

So:

    jest: {
      transformIgnorePatterns: ['node_modules/(?!(@modern-js|@abc)/)'],
    },

This works just fine. I missed that in the docs but found it.

So this all works for me so question answered.