jest.config.js

const config = {
  // The root of your source code, typically /src
  // `<rootDir>` is a token Jest substitutes
  roots: ["<rootDir>/src"],

  // Jest transformations -- this adds support for TypeScript
  // using ts-jest
  transform: {
    "^.+\\.tsx?$": "ts-jest",
  },

  // Runs special logic, such as adds special
  // extended assertions to Jest
  setupFilesAfterEnv: ["@testing-library/jest-dom/extend-expect"],

  // Test spec file resolution pattern
  // Matches parent folder `__tests__` and filename
  // should contain `test` or `spec`.
  testRegex: "(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$",

  // Module file extensions for importing
  moduleFileExtensions: ["ts", "tsx", "js", "jsx", "json", "node"],

  // run tests in the browser environment
  testEnvironment: "jsdom",

  // map non-code files to mocks
  moduleNameMapper: {
    "\\.(css|less|sass|scss)$": "<rootDir>/src/__mocks__/styleMock.js",
    "\\.(gif|ttf|eot|svg)$": "<rootDir>/src/__mocks__/fileMock.js",
  },
};

export default config;