Create Unit Tests for the Controller and Interceptor

Implement unit tests for other NestJS components

A NestJS application contains many components. In this lesson, we’ll discuss unit testing for different NestJS components. We’ll delve into implementing unit tests for a controller and an interceptor with hands-on examples.

What components should be unit tested in NestJS?

When writing unit tests for a NestJS application, it’s generally advisable to focus on testing components that contain business logic or significantly impact the application’s functionality.

Below is the list of components that should be tested, as well as those that might not require unit tests.

Components to test

• Controllers: They handle incoming requests, and it’s crucial to test them to verify if they respond correctly to different scenarios, handle validation, and interact appropriately with services.

• Services: They contain the application’s business logic and are often the heart of the NestJS application. Testing service methods, including edge cases and error handling, is essential to validate their behavior.

• Interceptors: They can modify the request/response globally. Testing ensures they work as intended and don’t introduce unintended side effects.

• Guards: They control access to ...