Jest adoption guide: Overview, examples, and alternatives

Jest is a widely used JavaScript testing library developed by Facebook (now Meta) for unit and integration testing across various frameworks like React, Angular, and Node.js. Initially created for testing React components, Jest offers rich functionality such as mocking, assertion, code coverage, and exception context, making it suitable for both frontend and backend JavaScript projects. The library's architecture involves multiple packages for executing tests, with the Jest CLI tool orchestrating the process. Jest's features include extensive configuration options, snapshot testing, and interactive watch mode, which detects and runs tests related to code edits. Despite limitations such as slower execution speed compared to Mocha and experimental support for ECMAScript Modules, Jest remains a popular choice due to its built-in capabilities, ease of setup, and support from a large open-source community. It also integrates well with other libraries like Enzyme for React component testing, making it versatile for various testing scenarios.