Unit Testing for the signUp Method of AuthService

In this lesson, we’ll write our first tests for our virtual library. We’ll address the following scenarios:

• Handling email conflicts: We ensure the signUp method throws a ConflictException when an email is already in use.

• Dealing with unexpected errors: Check how the signUp method responds to unforeseen issues.

• Successful user registration: Ensure that the signUp function successfully hashes the password and saves the new user to the database.

Test: Handling email conflicts

• Objective: Ensure the signUp function correctly handles cases where a user tries to sign up with an email already in use.

Key points to test:

• The function throws a ConflictException when an email is already in use.

When a user attempts to sign up with an email already in our virtual library, userRepository.save responds with a unique violation error identified by the code 23505.

Let’s focus on line 32 in auth.service.ts, where we’ll simulate this behavior of userRepository.save. Let’s see how to do that: