Growing Object-Oriented Software, Guided by Tests (Rough Cuts)

Description

This is a working draft of a pre-release book. It is available before the published date as part of the Rough Cuts service.

Foreword by Kent Beck

"The authors of this book have led a revolution in the craft of programming by controlling the environment in which software grows.” --Ward Cunningham

“At last, a book suffused with code that exposes the deep symbiosis between TDD and OOD. This one's a keeper.” --Robert C. Martin

“If you want to be an expert in the state of the art in TDD, you need to understand the ideas in this book.”--Michael Feathers

Test-Driven Development (TDD) is now an established technique for delivering better software faster. TDD is based on a simple idea: Write tests for your code before you write the code itself. However, this "simple" idea takes skill and judgment to do well. Now there's a practical guide to TDD that takes you beyond the basic concepts. Drawing on a decade of experience building real-world systems, two TDD pioneers show how to let tests guide your development and “grow” software that is coherent, reliable, and maintainable.

Steve Freeman and Nat Pryce describe the processes they use, the design principles they strive to achieve, and some of the tools that help them get the job done. Through an extended worked example, you’ll learn how TDD works at multiple levels, using tests to drive the features and the object-oriented structure of the code, and using Mock Objects to discover and then describe relationships between objects. Along the way, the book systematically addresses challenges that development teams encounter with TDD--from integrating TDD into your processes to testing your most difficult features. Coverage includes

•   Implementing TDD effectively: getting started, and maintaining your momentum

    throughout the project

•   Creating cleaner, more expressive, more sustainable code

•   Using tests to stay relentlessly focused on sustaining quality

•   Understanding how TDD, Mock Objects, and Object-Oriented Design come together

    in the context of a real software development project

•   Using Mock Objects to guide object-oriented designs

•   Succeeding where TDD is difficult: managing complex test data, and testing persistence

    and concurrency

Sample Content

Table of Contents

Foreword     xv

Preface     xvii

Acknowledgments     xxi

About the Authors     xxiii

PART I: INTRODUCTION     1

Chapter 1: What Is the Point of Test-Driven Development?     3

Software Development as a Learning Process     3

Feedback Is the Fundamental Tool     4

Practices That Support Change     5

Test-Driven Development in a Nutshell     6

The Bigger Picture     7

Testing End-to-End     8

Levels of Testing     9

External and Internal Quality     10

Chapter 2: Test-Driven Development with Objects     13

A Web of Objects     13

Values and Objects     13

Follow the Messages     14

Tell, Don’t Ask     17

But Sometimes Ask     17

Unit-Testing the Collaborating Objects     18

Support for TDD with Mock     19

Chapter 3: An Introduction to the Tools     21

Stop Me If You’ve Heard This One Before     21

A Minimal Introduction to JUnit 4     21

Hamcrest Matchers and assertThat()     24

jMock2: Mock Objects     25

PART II: THE PROCESS OF TEST-DRIVEN DEVELOPMENT     29

Chapter 4: Kick-Starting the Test-Driven Cycle     31

Introduction     31

First, Test a Walking Skeleton     32

Deciding the Shape of the Walking Skeleton     33

Build Sources of Feedback     35

Expose Uncertainty Early     36

Chapter 5: Maintaining the Test-Driven Cycle     39

Introduction     39

Start Each Feature with an Acceptance Test     39

Separate Tests That Measure Progress from Those That Catch Regressions     40

Start Testing with the Simplest Success Case     41

Write the Test That You’d Want to Read     42

Watch the Test Fail     42

Develop from the Inputs to the Outputs     43

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