Summary

In this chapter, we discussed code smells and anti-patterns. The right design principles can help keep your code focused and minimal and slow the rate at which it naturally accumulates complexity. This helps keep your code in good form and resist accumulating technical debt.

The most common maxim for quality programming is SOLID, following the Single Responsibility Principle (SRP), making code open for extension while being closed to modification, the Liskov Substitution Principle (LSP) advocating for low coupling with polymorphic code, the interface segregation principle focused on several smaller interfaces over one larger interface, and the Dependency Inversion Principle (DIP) which talks about reducing coupling by having classes take in the things they need from outside of the class.

Now that we’ve established how to write SOLID code, we’ll explore some advanced testing techniques that can help test code built using these principles.