Steve Freeman, Nat Pryce

Growing Object-Oriented Software, Guided by Tests (eBook, ePUB)

• Format: ePub

Produktbeschreibung

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

---

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Produktdetails

• Verlag: Pearson ITP
• Seitenzahl: 384
• Altersempfehlung: ab 18 Jahre
• Erscheinungstermin: 12. Oktober 2009
• Englisch
• ISBN-13: 9780321699763
• Artikelnr.: 52849483

Autorenporträt

Steve Freeman is an independent consultant specializing in Agile software development. A founder member of the London Extreme Tuesday Club, he was chair of the first XPDay and is a frequent organizer and presenter at international conferences. Steve has worked in a variety of organizations, from writing shrink-wrap software for IBM, to prototyping for major research laboratories. Steve has a Ph.D. from Cambridge University, and degrees in statistics and music. Steve is based in London, UK.

Nat Pryce has worked as a programmer, architect, trainer, and consultant in a variety of industries, including sports reportage, marketing communications, retail, telecoms, and finance. With a Ph.D. from Imperial College London, he has also worked on research projects and does occasional university teaching. An early adopter of Extreme Programming, he has written or contributed to several open source libraries that support Test Driven Development. He was one of the founding organizers of the London XPDay and regularly presents at international conferences. Nat is based in London, UK.

Freeman and Pryce were joint winners of the 2006 Agile Alliance Gordon Pask award.

Inhaltsangabe

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
Unit-Test Behavior, Not Methods     43
Listen to the Tests     44
Tuning the Cycle     45
 
Chapter 6: Object-Oriented Style     47
Introduction     47
Designing for Maintainability     47
Internals vs. Peers     50
No And’s, Or’s, or But’s     51
Object Peer Stereotypes     52
Composite Simpler Than the Sum of Its Parts     53
Context Independence     54
Hiding the Right Information     55
An Opinionated View     56
 
Chapter 7: Achieving Object-Oriented Design     57
How Writing a Test First Helps the Design     57
Communication over Classification     58
Value Types     59
Where Do Objects Come From?     60
Identify Relationships with Interfaces     63
Refactor Interfaces Too     63
Compose Objects to Describe System Behavior     64
Building Up to Higher-Level Programming     65
And What about Classes?     67
 
Chapter 8: Building on Third-Party Code     69
Introduction     69
Only Mock Types That You Own     69
Mock Application Objects in Integration Tests     71
 
PART III: A WORKED EXAMPLE     73
 
Chapter 9: Commissioning an Auction Sniper     75
To Begin at the Beginning     75
Communicating with an Auction     78
Getting There Safely     79
This Isn’t Real     81
 
Chapter 10: The Walking Skeleton     83
Get the Skeleton out of the Closet     83
Our Very First Test     84
Some Initial Choices     86
 
Chapter 11: Passing the First Test     89
Building the Test Rig     89
Failing and Passing the Test     95
The Necessary Minimum     102
 
Chapter 12: Getting Ready to Bid     105
An Introduction to the Market     105
A Test for Bidding     106
The AuctionMessageTranslator     112
Unpacking a Price Message     118
Finish the Job     121
 
Chapter 13: The Sniper Makes a Bid     123
Introducing AuctionSniper     123
Sending a Bid     126
Tidying Up the Implementation     131
Defer Decisions     136
Emergent Design     137
 
Chapter 14: The Sniper Wins the Auction     139
First, a Failing Test     139
Who Knows about Bidders?     140
The Sniper Has More to Say     143
The Sniper Acquires Some State     144
The Sniper Wins     146
Making Steady Progress     148
 
Chapter 15: Towards a Real User Interface     149
A More Realistic Implementation     149
Displaying Price Details     152
Simplifying Sniper Events     159
Follow Through     164
Final Polish     168
Observations     171
 
Chapter 16: Sniping for Multiple Items     175
Testing for Multiple Items     175
Adding Items through the User Interface     183
Observations     189
 
Chapter 17: Teasing Apart Main     191
Finding a Role     191
Extracting the Chat     192
Extracting the Connection     195
Extracting the SnipersTableModel     197
Observations     201
 
Chapter 18: Filling In the Details     205
A More Useful Application     205
Stop When We’ve Had Enough     205
Observations     212
 
Chapter 19: Handling Failure     215
What If It Doesn’t Work?     215
Detecting the Failure     217
Displaying the Failure     218
Disconnecting the Sniper     219
Recording the Failure     221
Observations     225
 
PART IV: SUSTAINABLE TEST-DRIVEN DEVELOPMENT     227
 
Chapter 20: Listening to the Tests     229
Introduction     229
I Need to Mock an Object I Can’t Replace (without Magic)     230
Logging Is a Feature     233
Mocking Concrete Classes     235
Don’t Mock Values     237
Bloated Constructor     238
Confused Object     240
Too Many Dependencies     241
Too Many Expectations     242
What the Tests Will Tell Us (If We’re Listening)     244
 
Chapter 21: Test Readability     247
Introduction     247
Test Names Describe Features     248
Canonical Test Structure     251
Streamline the Test Code     252
Assertions and Expectations     254
Literals and Variables     255
 
Chapter 22: Constructing Complex Test Data     257
Introduction     257
Test Data Builders     258
Creating Similar Objects     259
Combining Builders     261
Emphasizing the Domain Model with Factory Methods     261
Removing Duplication at the Point of Use     262
Communication First     264
 
Chapter 23: Test Diagnostics     267
Design to Fail     267
Small, Focused, Well-Named Tests     268
Explanatory Assertion Messages     268
Highlight Detail with Matchers     268
Self-Describing Value     269
Obviously Canned Value     270
Tracer Object     270
Explicitly Assert That Expectations Were Satisfied     271
Diagnostics Are a First-Class Feature     271
 
Chapter 24: Test Flexibility     273
Introduction     273
Test for Information, Not Representation     274
Precise Assertions     275
Precise Expectations     277
“Guinea Pig” Objects     284
 
PART V: ADVANCED TOPICS     287
 
Chapter 25: Testing Persistence     289
Introduction     289
Isolate Tests That Affect Persistent State     290
Make Tests Transaction Boundaries Explicit     292
Testing an Object That Performs Persistence Operations     294
Testing That Objects Can Be Persisted     297
But Database Tests Are S-l-o-w!     300
 
Chapter 26: Unit Testing and Threads     301
Introduction     301
Separating Functionality and Concurrency Policy     302
Unit-Testing Synchronization     306
Stress-Testing Passive Objects     311
Synchronizing the Test Thread with Background Threads     312
The Limitations of Unit Stress Tests     313
 
Chapter 27: Testing Asynchronous Code     315
Introduction     315
Sampling or Listening     316
Two Implementations     318
Runaway Tests     322
Lost Updates     323
Testing That an Action Has No Effect     325
Distinguish Synchronizations and Assertions     326
Externalize Event Sources     326
 
Afterword: A Brief History of Mock Objects     329
Appendix A: jMock2 Cheat Sheet     335
Appendix B: Writing a Hamcrest Matcher     343
Bibliography     347
Index     349