TDD with the Single-Responsibility Principle

Let’s start with what I think is one of the most important principles in the SOLID principles. Are you familiar with god classes or objects – where one class can do almost everything? A single class for login, registration, displaying registered users, and so on? If there are two developers working on the same god class, can you already imagine how challenging that can be? And what happens after you deploy it to production and then an issue is found in the part where you display a list of registered users? You will have to change or fix that god class, but now the same class for login and registration has been modified and these processes may be compromised too. You run a bigger risk of introducing regressions to your login and registration functionalities by just trying to fix the list of registered users. You fix one feature, and there’s a greater risk of breaking other features.

This is where the SRP will start...