jest.config.js

module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  roots: ['<rootDir>/src'],
  testPathIgnorePatterns: ['<rootDir>/dist/', '<rootDir>/node_modules/'],
  transform: {
    '^.+\\.(ts|tsx)$': 'ts-jest',
  },
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
  // https://github.com/zeit/next.js/issues/8663#issue-490553899
  globals: {
    // we must specify a custom tsconfig for tests because we need the typescript transform
    // to transform jsx into js rather than leaving it jsx such as the next build requires. you
    // can see this setting in tsconfig.jest.json -> "jsx": "react"
    'ts-jest': {
      tsconfig: '<rootDir>/tsconfig.json',
    },
  },
  moduleNameMapper: {
    '\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$':
      '<rootDir>/__mocks__/fileMock.js',
    '\\.(css|less)$': '<rootDir>/__mocks__/styleMock.js',
  },
};