How to use Jest to test functions using crypto or window.msCrypto

When running unit tests with Jest in react the window.crypto API is causing problems. I haven’t found a way to incorporate crypto in Jest without installing other packages which is something I can’t do. So without using another npm package is there a way to test functions that use: crypto.getRandomValues() in them that doesn’t crash Jest? Any links, advice, or tips are appreciated

Answer

Use the following code to set up the crypto property globally. It will allow Jest to access

• window.crypto in the browser environment
• global.crypto in non-browsers environments. (Node/Typescript scripts).

It uses the globalThis which is now available on most of the latest browsers as well as Node.js 12+

const crypto = require('crypto');

Object.defineProperty(globalThis, 'crypto', {
  value: {
    getRandomValues: arr => crypto.randomBytes(arr.length)
  }
});