The probably use an existing, well tested tool for user authentication (why reinvent the wheel?), or have comprehensive coverage for it already. There's no reas

The probably use an existing, well tested tool for user authentication (why reinvent the wheel?), or have comprehensive coverage for it already. There's no reason for tests for logging in to be slow either way. And after all, it's a social media app, it doesn't have to run perfectly all the time.