jest.config.js

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: './'
});

const customJestConfig = {
  collectCoverage: true,
  // on node 14.x coverage provider v8 offers good speed and more or less good report
  coverageProvider: 'v8',
  collectCoverageFrom: [
    '**/*.{js,jsx,ts,tsx}',
    '!**/*.d.ts',
    '!**/node_modules/**',
    '!<rootDir>/out/**',
    '!<rootDir>/.next/**',
    '!<rootDir>/*.config.js',
    '!<rootDir>/coverage/**'
  ],
  moduleNameMapper: {
    // Handle CSS imports (with CSS modules)
    // https://jestjs.io/docs/webpack#mocking-css-modules
    '^.+\\.module\\.(css|sass|scss)$': 'identity-obj-proxy',

    // workaround to support non esmodule compiled package:
    // jest-module name mapping will actually roll up packages
    // with name transforms, even if they are accessed the same way
    uiDotEnv: ['<rootDir>/node_modules/@uidotdev/usehooks'],
    nanoid: ['<rootDir>/node_modules/nanoid'],

    // Handle CSS imports (without CSS modules)
    '^.+\\.(css|sass|scss)$': '<rootDir>/__mocks__/styleMock.js',

    // Handle image imports
    // https://jestjs.io/docs/webpack#handling-static-assets
    '^.+\\.(png|jpg|jpeg|gif|webp|avif|ico|bmp|svg)$/i': `<rootDir>/__mocks__/fileMock.js`,

    // Handle module aliases
    '^@/(.*)$': '<rootDir>/src/$1'
  },
  setupFilesAfterEnv: ['@testing-library/jest-dom'],
  // Add more setup options before each test is run
  // setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
  testPathIgnorePatterns: ['<rootDir>/.next/'],
  transformIgnorePatterns: [
    '<rootDir>/node_modules/((!@uidotdev/usehooks)|(!nanoid))'
  ],
  testEnvironment: 'jest-environment-jsdom',
  transform: {
    // Use babel-jest to transpile tests with the next/babel preset
    // https://jestjs.io/docs/configuration#transform-objectstring-pathtotransformer--pathtotransformer-object
    '^.+\\.(js|jsx|ts|tsx)$': ['babel-jest', { presets: ['next/babel'] }]
  }
};

module.exports = async () => ({
  ...(await createJestConfig(customJestConfig)())
});