Testing Authentication Services

This lesson will explore unit testing, an essential part of building reliable software.

After developing book management and user authentication features in our virtual library, it’s time to learn how to apply unit testing to our application.

This lesson will set up an appropriate testing environment for the AuthService and write a basic test to ensure everything works correctly.

Why unit testing?

Unit testing is an essential step in software development, involving each application part’s isolation and detailed examination. It’s necessary for services like the AuthService.

By thoroughly testing this service, we can ensure our virtual library’s authentication process is secure and works as intended.

Writing unit testing helps us maintain high-quality code. It’s also a proactive measure for detecting issues early in the development cycle. This early detection can save significant time and resources, preventing small bugs from becoming major problems.

Setting up the basic test structure

NestJS leverages Jest, a widely used JavaScript testing framework, to handle its testing needs. One of the advantages of using Jest with NestJS is that it’s already integrated, eliminating the need for separate installations. Jest recognizes test files by their .spec.ts or .test.ts suffixes.

Step 1: Writing our first test

The first step in our testing journey is to write a basic test in the auth.service.spec.ts file. This test will introduce Jest’s fundamental methods and establish a foundation for more complex tests.