A well-functioning login system should provide a seamless experience for valid users while maintaining strong security measures against incorrect login attempts. Issues such as unclear error messages, improper redirects, or session handling problems can negatively impact usability and security.

Testing different scenarios, including valid logins, incorrect credentials, and session expirations, helps identify potential weaknesses.

To validate authentication, the login process is tested with correct and incorrect credentials. A successful login should redirect the user to the appropriate section, displaying personalized content. Incorrect attempts should trigger clear error messages without exposing sensitive information.

Proper session handling, logout functionality, and security measures such as account lockout after multiple failures are also checked to ensure a robust authentication system.