Jest Configuration Overview 📜

Jest is a popular JavaScript testing framework that provides a zero-configuration setup out of the box. However, customizing its behavior often requires tweaking the jest.config.js file. Here's a guide to help you understand and modify Jest configurations effectively.

Key Configuration Options 📝

• testMatch: Specifies which files Jest should treat as test files.
  ✅ Default: **/*.(spec|test).js?(on)

• testEnvironment: Sets the environment for tests.
  🚀 Common options: jsdom, node, react-native

• setupFiles: Runs files at the beginning of each test.
  📁 Example: ['./setupTests.js']

• moduleNameMapper: Maps module names to file paths.
  🔗 Useful for mocking modules like ^\.(svg|css|styl|less|sass|scss)$

Configuration File Location 📁

• Create a file named jest.config.js in the root of your project.
• For TypeScript projects, use jest.config.ts instead.

How to Use 🧪

1. Basic Setup

   module.exports = {
     testMatch: ['**/*.(spec|test).js?(on)'],
     testEnvironment: 'node',
   };
   

2. Advanced Customization
   Explore more options → /en/docs/jest/configuration
   📚 This link guides you through environment-specific configurations.

Tips 🔍

• Use jest --config to specify a custom config file.
• Always test your configuration changes with npm test.

💡 Image keyword: `jest_config` (representing the configuration file)