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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Build robust Scala applications by implementing the fundamentals of test-driven development in your workflow
About This Book
- Get a deep understanding of various testing concepts such as test-driven development (TDD) and BDD
- Efficient usage of the built-in Scala features such as ScalaTest, specs2, and Scala check
- Change your approach towards problem solving by thinking about the boundaries of the problem and its definition rather than focusing on the solution
Who This Book Is For
This book is for Scala developers who are looking to write better quality and easily maintainable code. No previous knowledge of TDD/BDD is required.
What You Will Learn
- Understand the basics of TDD and its significance
- Refactoring tests to build APIs in order to increase test coverage
- How to leverage the inbuilt Scala testing modules like ScalaTest, specs2 and Scala Check
- Writing test fixtures and apply the concepts of BDD
- How to divide tests to run at different points in continuous delivery cycle
- Benefits of refactoring and how it affects the final quality of code produced
- Understanding of SBT based build environment and how to use it to run tests
- The fundamentals of mocking and stubbing in Scala and how to use it efficiently
In Detail
Test-driven development (TDD) produces high-quality applications in less time than is possible with traditional methods. Due to the systematic nature of TDD, the application is tested in individual units as well as cumulatively, right from the design stage, to ensure optimum performance and reduced debugging costs.
This step-by-step guide shows you how to use the principles of TDD and built-in Scala testing modules to write clean and fully tested Scala code and give your workflow the change it needs to let you create better applications than ever before.
After an introduction to TDD, you will learn the basics of ScalaTest, one of the most flexible and most popular testing tools around for Scala, by building your first fully test-driven application. Building on from that you will learn about the ScalaTest API and how to refactor code to produce high-quality applications.
We'll teach you the concepts of BDD (Behavior-driven development) and you'll see how to add functional tests to the existing suite of tests. You'll be introduced to the concepts of Mocks and Stubs and will learn to increase test coverage using properties.
With a concluding chapter on miscellaneous tools, this book will enable you to write better quality code that is easily maintainable and watch your apps change for the better.
Style and approach
This step-by-step guide explains the significance of TDD in Scala through various practical examples. You will learn to write a complete test-driven application throughout the course of the book.
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Seitenzahl: 187
Veröffentlichungsjahr: 2016
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Table of Contents
Scala Test-Driven Development
Scala Test-Driven Development
Copyright © 2016 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: October 2016
Production reference: 1211016
Published by Packt Publishing Ltd.
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ISBN 978-1-78646-467-5
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Credits
Author
Gaurav Sood
Copy Editors
Charlotte Carneiro
Safis Editing
Reviewer
Román García
Project Coordinator
Sheejal Shah
Commissioning Editor
Kunal Parikh
Proofreader
Safis Editing
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Indexer
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Content Development Editor
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About the Author
Gaurav Sood is a Scala and XQuery consultant who consults through his own company Omkaar Technologies Limited. He started playing with computers at a very early age and eventually went onto complete his post-graduate degree in computer sciences.
After working for an Indian software service house for a couple of years, he decided to start his own consultancy business. Since then, his company has provided services to a few Tier 1 Investment banks, the government of the United Kingdom, and publishing houses. He has gained an irrefutable reputation and distinction in the industry. Gaurav has previously worked with HSBC, Deutsche Bank, Reed Elsevier, Lexis Nexis, John Wiley & Sons, HMRC, and Associated News, amongst other smaller names in the industry.
When he is not consulting or writing, Gaurav can be seen making a fuss of his family. He likes spending time with his beautiful wife and two sons. He also loves volunteering for charity fund raising through sponsored runs. Gaurav also runs a small charitable trust in Shimla, India (New Life), which helps provide education to under-privileged children.
Acknowledgments
I would like to start by thanking God for the courage and determination to write this book. There are many people I would like to express my gratitude to, for helping me with this book. These people have seen me through this book, provided support, offered comments, proofread my work, and been a critic when I needed one.
I want to thank my family for being my strength, my parents, Satish and Brij, wife, Khushboo, and two little boys, Johan and Jairus, who have been my strength. They have supported and encouraged me in spite of all the time it took me away from them. It was a lingering and arduous voyage for them. I would also like to thank my in-laws, Hardeep and Kawaljit, along with my siblings and friends for encouraging me to consider writing this book. They have always believed in me.
I would also like to thank Packt Publishing, their extremely helpful editorial staff and technical reviewers for enabling me to publish this book and encouraging me every step of the way. I would also like to thank Artima Inc, for their permission to refer to their work.
Special thanks once again to my lovely wife Khushboo. Without you, this book wouldn’t have been possible.
Last but not the least: I beg forgiveness to all those who have been with me over the years and whose names I have failed to mention.
About the Reviewer
Román García has been a self-taught software engineer for the last two decades, and is currently CTO at Fravega.com, one of the biggest retail companies in Argentina where he resides. Previously, he worked as a software architect for Despegar.com, ZonaJobs.com, DeRemate.com, and others. An avid cowboy programmer, he is passionate about software development, clean code, test-driven development, and madly in love with the Scala programming language.
I’d like to thank my parents for all their support during the early years, when I found my passion for programming, and, last but not least, to my loving wife, Elisabeth, and my two kids, Manuela and Joaquin, for all the love they brought to my life.
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Preface
Test-Driven Development (TDD) goes hand-in-hand with Agile practices, which is gradually becoming the undisputed standard process or delivering quality software on time. The TDD process originated from the need to better understand and refine the requirements for a system.
Scala has gradually, despite all apprehensions, made a niche for itself as the language of choice for delivering modern versatile systems and microservices. It is slowly and steadily replacing the conventional object-oriented models with more robust and immutable functional constructs. The popularity of Scala emanates from the fact that it provides a bridge for developers to make a transition from the object-oriented to the functional world.
Scala, like all other languages, can allow developers to get so engrossed in its intricacies and magic that the real purpose of the application can easily get lost in over-engineering. Therefore, TDD is required to keep the application code tightly tied to the requirements.
What this book covers
Chapter 1, Hello, TDD!, contains a brief introduction of TDD and Agile process. We discussed the benefits of TDD and how and why it needs to be used.
Chapter 2, First Test-Driven Application, creates our very first working application using TDD. The purpose of this chapter is to provide a quick win and give a taste of what lies ahead.
Chapter 3, Clean Code Using ScalaTest, discusses some of the principles of clean code and delves into the ScalaTest framework.
Chapter 4, Refactor Mercilessly, discusses various refactoring techniques and their benefits. The idea is to build a gradual appreciation of the refactoring process.
Chapter 5, Another Level of Testing, discusses the concepts of functional testing and behaviour-driven development.
Chapter 6, Mock Objects and Stubs, takes an in-depth look into the mocking frameworks that can be used with ScalaTest and Specs2 to enable mocking out the dependencies during testing.
Chapter 7, Property-Based Testing, discusses the techniques of writing tests that are driven from inputs provided in the form of tabular data or that is randomly generated.
Chapter 8, Scala TDD with Specs2, looks at an alternative testing framework for test-driving Scala code. We also compare ScalaTest and Specs2 so the reader can make an informed choice.
Chapter 9, Miscellaneous and Emerging Trends in Scala TDD, explores some new techniques, features, and processes that may soon become incorporated into the mainstream application development process.
What you need for this book
The following software is recommended for use with this book:
Who this book is for
This book is for Scala developers who are looking to write better quality and easily maintainable code. No previous knowledge of TDD/BDD is required.
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Chapter 1. Hello, TDD!
Let's begin this chapter with a brief introduction to Test-Driven Development (or TDD, as it's colloquially known), covering some of its basic concepts. The main goal of this chapter is to give you an appreciation of TDD practices and for you to ascertain what technological niche it fulfills.
This chapter will explore:
What is TDD?
TDD is the practice of writing your tests before writing any application code.
TDD is a practice that is most frequently and strongly advocated by Agile practitioners and theorists. It is one of the major pillars of the Agile methodology. There have been various studies over the years and many white papers published, which clearly state that the use of TDD has resulted in a more successful and robust application code.
TDD consists of the following iterative steps:
This process is also referred to as Red-Green-Refactor-Repeat.
TDD became more prevalent with the use of the Agile software development process, though it can be used as easily with any of the Agile development process's predecessors, such as Waterfall, Iterative, and so on.
At the height of the software revolution in the 1990s, it became evident that the draconian processes and practices developed mostly in the 1980s were slow, officious, likely to fail, and rigid. The Agile development process was created at the Snowbird ski resort in the Wasatch Mountains of Utah. Here, 17 industry thought-leaders met to discuss the problems of the development processes being used with the common goal of creating an adaptive development process that has people at its core rather than requirements. This resulted in the Agile manifesto:
Though TDD is not specifically mentioned in the Agile manifesto (http://agilemanifesto.org), it has become a standard methodology used with Agile. Saying this, you can still use Agile without using TDD.
Why TDD?
The need for TDD arises from the fact that there can be constant changes to the application code. This becomes more of a problem when we are using the Agile development process, as it is inherently an iterative development process.
Here are some of the advantages, which underpin the need for TDD:
Changing our approach to problem solving
Everything we have discussed thus far makes perfect sense in theory, but we need to look at what needs to change in our approach to problem solving if we are to practice the TDD ethos.
I will be more biased towards "me", and will discuss how I made the transition into "TDD land". When I was first asked to build an application using test-driven principles my natural reaction was to doubt every aspect of it. My client at that time had hired a reputable external Agile enablement company to hand-hold developers to learn these new age shenanigans.
My first few questions were "Is it not more time consuming?", "Isn't it QA's job to test?", "Why do we need to test-drive even a very trivial bit of code?", and many more (mostly whiney) questions.
