microsoft-authentication-library-for-js: msal-react: only publishing as ESM breaks jest tests

hi, same issue on my project! @jansepke can you suggest me how i can mock the entire msal-react library in order to unblock the tests, please?

you can mock it like this: jest.mock('@azure/msal-react', () => ({ useMsal: jest.fn(), }));

EDIT: since I see a few downvotes I would like to explain that my suggestion is not a solution to the issue. I shows how @jansepke and I currently work around it by mocking the entire msal library until the issue is fixed. Keeping this workaround is not desirable.

I’m using create-react-app and I was able to resolve the Jest issue by adding the following into my package.json:

  "jest": {
    "transformIgnorePatterns": [
      "node_modules/(?!(@azure/msal-react)).*\\.js$"
    ]
  },

If you’re not using create-react-app you should be able to add this into your jest.config.js file.

Docs: https://jestjs.io/docs/configuration#transformignorepatterns-arraystring

The fix won’t work with Next.js which overwrites jest config.

1. compile with es-build to a vendor folder and check it in

npx esbuild @azure/msal-react --bundle --platform=node --sourcemap=inline --outfile=vendor/@azure/msal-react.js

1. update your jest config - map @azure/msal-react to your newly vendored module

const nextJest = require("next/jest");

const createJestConfig = nextJest({
  // Provide the path to your Next.js app to load next.config.js and .env files in your test environment
  dir: "./",
});

// Add any custom config to be passed to Jest
const customJestConfig = {
  setupFilesAfterEnv: ["<rootDir>/jest.setup.js"],
  testEnvironment: "jest-environment-jsdom",
  moduleNameMapper: {
    "@azure/msal-react": "<rootDir>/vendor/@azuremsal-react",
  },
};

// createJestConfig is exported this way to ensure that next/jest can load the Next.js config which is async
module.exports = createJestConfig(customJestConfig);

1. mock

jest.mock('@azure/msal-react', () => ({ useMsal: jest.fn(), }));

Does anyone have insights into why this problem is impacting my UAT pipeline while it doesn’t seem to have the same effect on my local machine? Also, is there a possible solution or workaround for this issue within a React project?

“Error [ERR_REQUIRE_ESM]: require() of ES Module /app/node_modules/@azure/msal-react/dist/index.js from /app/dist/server/assets/all.page.9a5890d9.js not supported.”