Test Error Due to Falso

[mtpultz1977]

I've got a new install of Angular 14.x using Jest 28.x based on the Angular-Jest-Preset with Node v14.x. The application tests were working until I started using Falso, and I'm not sure I understand the error. The files appear to CommonJS based on the last line of the error so it doesn't appear to be an ESM error. Does any know why this is happening and how to fix it?

    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/mtpultz/Projects/respondent/website/apps/admin/node_modules/uuid/dist/esm-browser/index.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export { default as v1 } from './v1.js';
                                                                                      ^^^^^^

    SyntaxError: Unexpected token 'export'

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1796:14)
      at Object.<anonymous> (node_modules/@ngneat/falso/index.cjs.js:6:12)

[NetanelBasal]

The error is from the uuid library

[mtpultz1977]

Looking through UUID package errors it seems like it uses ESM in Node v14, but reconfiguring Jest to use ESM using the Angular Jest Preset docs causes everything to fail and doesn't fix the issue. I'd downgrade to Node v12, but the Angular CLI doesn't support it anymore.

[tomalaforge]

Hi @NetanelBasal and @mtpultz1977,

What did you do to resolve this issue and make the test passes with falso on angular v14 and jest v28?

[mtpultz]

@tomalaforge @NetanelBasal I couldn't figure it out 😢. I thought it might be our Jest config like ES modules vs CommonJS, but still got the error and UUID says they support CommonJS. I tried installing different versions of UUID in our project as a devDependency, and stepping back the version of Falso, but no luck. It's our only Angular 14 project and the only one we can't use Falso.

[NetanelBasal]

Can someone send a link to a simple reproduction on Github, please?

[mtpultz]

Hi, I created a new Angular 14 project and added Jest v28. I added a single test to the AppComponent that imports and uses randText() from Falso, and if you run npm run test you'll get the UUID exception - https://github.com/mtpultz/uuid-issue

[NetanelBasal]

@mtpultz you can use:

  transformIgnorePatterns: [
    "node_modules/(?!uuid).+\\.js$"
  ],

[mtpultz1977]

I tried adding that to the transformIgnorePatterns and I still get the error with:

transformIgnorePatterns: [
  'node_modules/(?!.*\\.mjs$)',
  'node_modules/(?!uuid).+\\.js$',
],

[NetanelBasal]

Remove the first one

[mtpultz]

That definitely works, but do I not need the line I removed above? The jest-preset-angular docs seem to suggest that it is the exposed configuration.

"transformIgnorePatterns": instruct Jest to transform any .mjs files which come from node_modules.

const snapshotSerializers = require('../build/serializers');

module.exports = {
  globals: {
    'ts-jest': {
      tsconfig: '<rootDir>/tsconfig.spec.json',
      stringifyContentPathRegex: '\\.(html|svg)$',
    },
  },
  moduleFileExtensions: ['ts', 'html', 'js', 'json', 'mjs'],
  resolver: 'jest-preset-angular/build/resolvers/ng-jest-resolver.js',
  snapshotSerializers,
  testEnvironment: 'jsdom',
  transformIgnorePatterns: ['node_modules/(?!.*\\.mjs$)'],
  transform: {
    '^.+\\.(ts|js|mjs|html|svg)$': 'jest-preset-angular',
  },
};

[erichartline]

I was able to fix this by adding '^uuid$': 'uuid' to my Jest config's moduleNameWrapper using Jest 29.