jest.config.js

// IMPORTANT: https://www.typescriptlang.org/tsconfig#esModuleInterop
// "esModuleInterop" should be set to TRUE in tsconfig.json

module.exports = {
  globals: {
    "ts-jest": {
      // Tell ts-jest about our typescript config.
      // You can specify a path to your tsconfig.json file,
      // but since we're compiling specifically for node here,
      // this works too.
      tsConfig: {
        target: "es2019",
      },
    },
  },
  // Transforms tell jest how to process our non-javascript files.
  // Here we're using babel for .js and .jsx files, and ts-jest for
  // .ts and .tsx files.  You *can* just use babel-jest for both, if
  // you already have babel set up to compile typescript files.
  transform: {
    // This one will require babel config and additional babel deps.
    // "^.+\\.jsx?$": "babel-jest",
    "^.+\\.tsx?$": "ts-jest",
  },
  // In webpack projects, we often allow importing things like css files or jpg
  // files, and let a webpack loader plugin take care of loading these resources.
  // In a unit test, though, we're running in node.js which doesn't know how
  // to import these, so this tells jest what to do for these.
  moduleNameMapper: {
    // Resolve .css and similar files to identity-obj-proxy instead.
    ".+\\.(css|styl|less|sass|scss)$": `identity-obj-proxy`,
    // Resolve .jpg and similar files to __mocks__/file-mock.js
    ".+\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": `<rootDir>/src/__mocks__/file-mock.ts`,
  },
  // Tells Jest what folders to ignore for tests
  // testPathIgnorePatterns: [`node_modules`, `\\.cache`],

  // IMPORTANT: it's vital to have exactly "setupFilesAfterEnv"
  setupFilesAfterEnv: ["<rootDir>/src/setupTests.ts"],
};