Growing Object-Oriented Software, Guided by Tests

Chapter 6. Object-Oriented Style

Always design a thing by considering it in its next larger context—a chair in a room, a room in a house, a house in an environment, an environment in a city plan.

—Eliel Saarinen

Introduction

So far in Part II, we’ve talked about how to get started with the development process and how to keep going. Now we want to take a more detailed look at our design goals and our use of TDD, and in particular mock objects, to guide the structure of our code.

We value code that is easy to maintain over code that is easy to write.¹ Implementing a feature in the most direct way can damage the maintainability of the system, for example by making the code difficult to understand or by introducing hidden dependencies between components. ...