Jest and NestJS
Explore how to create a unit test using Jest.
Write unit test using Jest
In this lesson, we’ll explore the fundamentals of writing unit tests for NestJS applications using the Jest testing framework. Jest is a popular testing framework that provides a robust, developer-friendly environment for creating and executing tests.
Jest overview
Jest is a widely adopted JavaScript testing framework that stands out for its simplicity, speed, and developer-friendly features. Developed by Meta, Jest is designed to facilitate the testing of JavaScript applications, making it an excellent choice for various projects, including NestJS applications.
Jest comes bundled with built-in functionalities—such as test runners, assertion libraries, and mocking capabilities—streamlining the testing process for developers. Its easy-to-understand syntax and thorough documentation make it easier to learn and use.
NestJS itself does not mandate a specific unit testing framework. However, NestJS applications are often tested using Jest because Jest is the default testing framework recommended by the NestJS documentation. When we generate a new NestJS project using the official NestJS CLI, it includes a default Jest setup for testing. The generated project comes with sample unit tests that are preconfigured for Jest.
Benefits
Below are several advantages and features of Jest:
Zero config: Jest is designed to provide a great out-of-the-box experience, and it comes with sensible defaults that work for a wide range of projects. When we run Jest in a project that follows certain conventions, it automatically detects and runs tests without needing a separate configuration file.
Efficient: Jest excels in speed as its tests run concurrently, significantly reducing the overall test execution time.
Built-in code coverage: Jest comes with built-in code coverage support, providing a valuable metric for CI-based delivery ...