Book Image

Agile Technical Practices Distilled

By : Pedro M. Santos, Marco Consolaro, Alessandro Di Gioia
Book Image

Agile Technical Practices Distilled

By: Pedro M. Santos, Marco Consolaro, Alessandro Di Gioia

Overview of this book

The number of popular technical practices has grown exponentially in the last few years. Learning the common fundamental software development practices can help you become a better programmer. This book uses the term Agile as a wide umbrella and covers Agile principles and practices, as well as most methodologies associated with it. You’ll begin by discovering how driver-navigator, chess clock, and other techniques used in the pair programming approach introduce discipline while writing code. You’ll then learn to safely change the design of your code using refactoring. While learning these techniques, you’ll also explore various best practices to write efficient tests. The concluding chapters of the book delve deep into the SOLID principles - the five design principles that you can use to make your software more understandable, flexible and maintainable. By the end of the book, you will have discovered new ideas for improving your software design skills, the relationship within your team, and the way your business works.
Table of Contents (31 chapters)
Free Chapter
Section 1
Section 2
Section 3
Section 4
Chapter 21
License: CyberDojo

Parallel Change (Or Expand, Migrate, and Contract)

The technique of Parallel Change was an original idea of Joshua Kerievsky. It was explained in 2010, in a talk called The Limited Red Society. InfoQ, Joshua Kerievsky, The Limited Red Society:

Parallel Change, also known as expand, migrate, and contract, is a refactor pattern to implement breaking changes safely (staying in the green). It consists of three steps: expand, migrate, and contract.


Introduce new functionality by adding new code instead of changing existing code. If you are expanding a class or an interface, introduce new methods instead of changing existing ones. If the behavior from the outside is similar and only the implementation changes, duplicate existing tests and point them to the new code, leaving the existing tests untouched. Make sure tests for existing code are still working.

Implement new functionality starting from the tests, either...