Pragmatic Unit Testing in Java 8 with JUnit

Chapter 8Refactoring to Cleaner Code

Our systems are bloated! You can pick almost any system at random and spot obvious bits of rampant duplication—whether it’s a hundred-line-long method that’s almost a complete replication from another class or a few lines of utility code repeated megaumpteen times throughout. The cost of such duplication is significant: every piece of code duplicated increases the cost to maintain it, as well as the risk in making a change. You want to minimize the amount of duplication in your system’s code.

The cost of understanding code is also significant. A change requiring ten minutes of effort in clear, well-structured code can require hours of effort in convoluted, muddy code. You want to maximize the clarity in ...