Summary

In this chapter, we’ve gone through the SOLID principles one by one. We used our tests to kickstart the development of our solution code so that we can use them as examples for implementing the SOLID principles in real life.

We have covered the SRP, which helped us make a PHP class’s responsibility or capability more focused. The OCP helped us avoid the need for touching or modifying a class in some instances when we want to change its behavior. The LSP helped us be stricter about the behavior of an interface, making it easier for us to switch concrete objects implementing that interface without breaking the parent class’s behavior. The ISP helped us make the responsibility of an interface more focused – classes that implement this interface will no longer have empty methods just because they were declared by the interface. The DIP helped us quickly test our ToyCarCreator class even without creating a concrete implementation of its dependencies...