Behavior-Driven Development with Cucumber This page intentionally left blank Behavior-Driven Development with Cucumber Better Collaboration for Better Software Richard Lawrence with Paul Rayner Boston • Columbus • New York • San Francisco • Amsterdam • Cape Town • Dubai London • Madrid • Milan • Munich • Paris • Montreal • Toronto • Delhi • Mexico City São Paulo • Sydney • Hong Kong • Seoul • Singapore • Taipei • Tokyo Many of the designations used by manufacturers and sellers to distinguish their Publisher products are claimed as trademarks. Where those designations appear in this book, Mark L. Taub and the publisher was aware of a trademark claim, the designations have been printed with initial capital letters or in all capitals. Acquisitions Editor Haze Humbert The authors and publisher have taken care in the preparation of this book, but make no expressed or implied warranty of any kind and assume no responsibility for errors Development Editor or omissions. 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Compositor codeMantra ISBN-13: 978-0-321-77263-3 ISBN-10: 0-321-77263-6 1 19 Cover photograph © Food Travel Stockforlife/Shutterstock Contents Acknowledgments . ix About the Authors . xi Chapter 1: Focusing on Value . 1 When Scrum Isn’t Enough . 3 Finding a High-Value Feature to Start With . 5 Before You Start with Cucumber . 7 Finding the First MMF . 8 Slicing an MMF into User Stories . 10 Summary . 14 Reference . 14 Chapter 2: Exploring with Examples . 15 BDD Is a Cooperative Game . 19 BDD Is a Whole Team Thing . 20 Allow Time and Space to Learn . 21 Flesh Out the Happy Path First . 27 Use Real Examples . 27 Example Mapping Gives the Discussion Structure . 28 Optimizing for Discovery . 32 Addressing Some Concerns . 33 Treat Resistance as a Resource . 39 Playing the BDD Game . 41 Opening . 42 Exploring . 42 Closing . 44 Summary . 45 References . 46 v vi Contents Chapter 3: Formalizing Examples into Scenarios . 47 Moving from Examples to Scenarios . 47 Feature Files as Collaboration Points . 51 BDD Is Iterative, Not Linear . 65 Finding the Meaningful Variations . 66 Gherkin: A Language for Expressive Scenarios . 66 Summary . 72 Resources . 72 Chapter 4: Automating Examples . 73 The Test Automation Stack . 76 Adjusting to Working Test-First . 82 Annotating Element Names in Mockups . 84 How Does User Experience Design Fit In to This? . 85 Did They Really Just Hard Code Those Results? . 89 Anatomy of a Step Definition . 90 Simple Cucumber Expressions . 91 Regular Expressions . 92 Anchors . 92 Wildcards and Quantifiers . 93 Capturing and Not Capturing . 93 Just Enough . 94 Custom Cucumber Expressions Parameter Types . 94 Beyond Ruby . 96 Slow Is Normal (at First) . 101 Choose Cucumber Based on Audience, Not Scope . 103 Summary . 104 Chapter 5: Frequent Delivery and Visibility . 105 How BDD Changes the Tester’s Role . 105 Exploratory Testing . 114 BDD and Automated Builds . 116 Faster Stakeholder Feedback . 119 How Getting to Done More Often Changes All Sorts of Things . 123 Frequent Visibility and Legacy Systems . 125 Documentation: Integrated and Living . 127 Contents vii Avoiding Mini-Waterfalls and Making the Change Stick . 131 Summary . 135 References . 135 Chapter 6: Making Scenarios More Expressive . 137 Feedback About Scenarios . 137 How to Make Your Scenarios More Expressive . 143 Finding the Right Level of Abstraction . 144 Including the Appropriate Details . 146 Expressive Language in the Steps . 147 Refactoring Scenarios . 150 Good Scenario Titles . 151 Summary . 151 References . 152 Chapter 7: Growing Living Documentation . 153 What Is Living Documentation and Why Is It Better? . 153 Cucumber Features and Other Documentation . 154 Avoid Gherkin in User Story Descriptions . 155 The Unexpected Relationship Between Cucumber Features and User Stories . 157 Stable Scenarios . 159 Growing and Splitting Features . 160 Split When Backgrounds Diverge . 160 Split When a New Domain Concept Emerges . 161 Secondary Organization Using Tags . 161 Structure Is Emergent . 163 Summary . 163 Chapter 8: Succeeding with Scenario Data . 165 Characteristics of Good Scenarios . 168 Independent . 168 Repeatable . 168 Researchable . ..