jest.config.ts

import nextJest from 'next/jest.js';

import type { Config } from '@jest/types';

const createJestConfig = nextJest({
  // Provide the path to your Next.js app to load next.config.js and .env files in your test environment
  dir: './',
});

// Add any custom config to be passed to Jest
const config: Config.InitialProjectOptions = {
  // Use SWC for transformations
  transform: {
    '^.+\\.(t|j)sx?$': [
      '@swc/jest',
      {
        jsc: {
          parser: {
            syntax: 'typescript',
            tsx: true,
            decorators: true,
          },
          transform: {
            react: {
              runtime: 'automatic',
            },
          },
          target: 'es2021',
        },
      },
    ] as [string, any],
  },

  // Add more setup options before each test is run
  setupFilesAfterEnv: ['<rootDir>/jest.setup.ts'],

  // Test environment
  testEnvironment: 'jest-environment-jsdom',

  // Module name mapper for path aliases
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
    '\\.(css|less|scss|sass)$': 'identity-obj-proxy',
  },

  // Coverage configuration
  collectCoverageFrom: [
    'src/**/*.{ts,tsx}',
    'app/**/*.{ts,tsx}',
    '!src/**/*.d.ts',
    '!src/**/__tests__/**',
    '!src/**/*.test.{ts,tsx}',
    '!src/**/*.spec.{ts,tsx}',
  ],

  // Test path ignore patterns
  testPathIgnorePatterns: [
    '<rootDir>/.next/',
    '<rootDir>/node_modules/',
    '<rootDir>/build/',
    '<rootDir>/out/',
  ],

  // Module file extensions
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json'],

  // Transform ignore patterns - empty array for ESM support
  transformIgnorePatterns: [],

  // Roots
  roots: ['<rootDir>'],

  // Test match patterns
  testMatch: ['**/__tests__/**/*.(ts|tsx|js)', '**/*.(test|spec).(ts|tsx|js)'],

  // Verbose output (not available in InitialProjectOptions, use CLI flag instead)
};

// createJestConfig is exported this way to ensure that next/jest can load the Next.js config which is async
export default createJestConfig(config);