Book Image

Test-Driven Java Development, Second Edition - Second Edition

By : Viktor Farcic, Alex Garcia
Book Image

Test-Driven Java Development, Second Edition - Second Edition

By: Viktor Farcic, Alex Garcia

Overview of this book

Test-driven development (TDD) is a development approach that relies on a test-first procedure that emphasizes writing a test before writing the necessary code, and then refactoring the code to optimize it.The value of performing TDD with Java, one of the longest established programming languages, is to improve the productivity of programmers and the maintainability and performance of code, and develop a deeper understanding of the language and how to employ it effectively. Starting with the basics of TDD and understanding why its adoption is beneficial, this book will take you from the first steps of TDD with Java until you are confident enough to embrace the practice in your day-to-day routine.You'll be guided through setting up tools, frameworks, and the environment you need, and we will dive right into hands-on exercises with the goal of mastering one practice, tool, or framework at a time. You'll learn about the Red-Green-Refactor procedure, how to write unit tests, and how to use them as executable documentation.With this book, you'll also discover how to design simple and easily maintainable code, work with mocks, utilize behavior-driven development, refactor old legacy code, and release a half-finished feature to production with feature toggles.You will finish this book with a deep understanding of the test-driven development methodology and the confidence to apply it to application programming with Java.
Table of Contents (18 chapters)
Title Page
Packt Upsell
Contributors
Preface
9
Refactoring Legacy Code – Making It Young Again
Index

The Red-Green-Refactor process


The Red-Green-Refactor process is the most important part of TDD. It is the main pillar, without which no other aspect of TDD will work.

The name comes from the states our code is in within the cycle. When in the red state, code does not work; when in the green state, everything is working as expected, but not necessarily in the best possible way. Refactor is the phase when we know that features are well covered with tests and thus gives us the confidence to change it and make it better.

Writing a test

Every new feature starts with a test. The main objective of this test is to focus on requirements and code design before writing the code. A test is a form of an executable documentation and can be used later on to get an understanding of what the code does or what are the intentions behind it.

At this point, we are in the red state since the execution of tests fails. There is a discrepancy between what tests expect from the code and what the implementation code...