Test-Driven Database Development

Public Interface? 56 Transition Safeguards 56 Read/Read Transition Tests 56 Run by the Class of Databases on Every Upgrade 60 Backup and Rollback on Fail 60 Making Transition Tests Leverage Transition Safeguards 60 Summary 61 Chapter 5 Enforcing Interface 63 Interface Strength 64 Stronger Coupling Languages 64 Weaker Coupling Languages 65 The Common Thread 66 Coupling to Database Classes 66 The Problem Is Duplication 66 Client-Object-Like Enforcement 67 Creating Demand for a DatabaseDesign Class 67 Specifying the DatabaseDesign Class 68 Getting Rid of Duplication with Multiple Client Platforms 70 What Happens When Coupling Goes Bad? 71 Eliminating Duplication Between Database Build and Client Code 71 Decoupling Implementation from Design 72 Sticking Point: Change 73 Designs Change Over Time 74 Document All Versions of Design 75 Couple to the Correct Version of the Design 77 Sticking Point: Coupling 78 Various Clients Couple to Various Versions 78 Having to Change Everything All the Time Is Duplication, Too 79 Introducing the Lens Concept 83 Virtual Lenses 85 The "Current" Lens 89 The "New" Lens 89 Summary 93 Chapter 6 Defining Behaviors 95 A New Group of Problems 96 No Encapsulation 96 Hide Everything 97 Business Logic in the Database 97 Knowledge, Information, and Behavior 98 Information 99 Knowledge 102 Behavior 102 Outside-In Development 106 Defining the Test 106 Growing Interface 108 Growing Behavior and Structures 109 Justification by Specification 111 Work Against Present Requirements, Not Future 111 Build in Increments 112 Limit Access to What Is Specified 112 Summary 113 Chapter 7 Building for Maintainability 115 Never Worry About the Future 116 Look for Opportunities in the Now 116 Design to Information 117 Translate Info and Knowledge with Behavior 121 Guard Knowledge with Fervor and Zeal 124 Not Changing Is the Most Dangerous Choice 124 Keep Your Design Natural 126 Deal with the Future When It Happens 127 Define New Design 128 Introduce Minimal Changes 129 Get Tests Passing 131 Stop, Think, Refactor 133 Summary 136 Chapter 8 Error and Remediation 137 Kinds of Errors 137 Axis: Is the Error Good or Bad? 138 Axis: Is the Error Released or Not? 140 Dealing with Good Errors 142 Just Fix It 142 Document Behavior Now 143 Trace Feature Back to Its Genesis 145 Dealing with Bad Errors 146 Unreleased Errors 147 Released Errors 150 Catastrophic Errors 156 Summary 157 Chapter 9 Design 159 Structures Versus Design 160 Structures: Execution Details 160 Tests and Class Information 162 What Is Design? 163 Buckets of Concepts 163 Mandatory Part of True TDD 166 Composition and Aggregation 167 Composition: One Thing with Multiple Parts 168 Aggregation: Connecting Distinct Things 172 Reuse 175 Avoid Developing the Same Thing Twice 175 Reuse by Composition or Aggregation 177 Abstraction 178 Identifying Opportunities for Abstraction 178 Encapsulating Behaviors 179 Finding Ways to Allow Variation in Dependencies 185 Dealing with the Time Problem 186 Summary 190 Chapter 10 Mocking 191 Testing Individual Behaviors 191 Why Encapsulate 192 Tests Test Everything Not Under Their Control 193 Controlling Irrelevant Behaviors from Tests 194 Mocking Controls Behaviors 194 Mocking in Object-Oriented Programming 195 Setup 195 Decoupling 199 Isolation 202 Integration 202 Mocking in Database Design 203 Example Problem 204 Example Solution 205 Composition 208 Aggregation 210 Designing for Testability 210 Summary 210 Chapter 11 Refactoring 213 What Refactoring Is 214 Changing Design Without Changing Behavior 214 In the Context of Passing Tests 215 Lower and Higher Risk Design Changes 222 Lower Risk: Changing Class-Level Design 222 Medium Risk: Rearranging Behavior Logic 223 Higher Risk: Altering Knowledge Containers 225 This Is Not an Invitation to Skip Testing 226 Summary 226 Chapter 12 Legacy Databases 227 Promoting to a Class 228 Deducing Initial Version 228 Pinning the Transition Behavior with Tests 231 Controlling Coupling 231 Identifying and Locking Down to Existing Uses 232 Encapsulating on Demand 234 Controlling Change 235 Test-Driving New Behaviors 235 Pinning Construction on Demand 237 Pinning Behavior on Demand 238 Implementing New Behavior 239 Finding Seams and Components 240 Finding Seams 240 Encapsulating Components 243 Summary 247 Chapter 13 The Facade Pattern 249 Encapsulation with a Facade 249 Explanation of Facade Pattern 250 New Test-Driven Facade Database 254 Compositional Alternative 261 To Encapsulate or Not 261 Strangling the Old Interface 262 Transferring Changing Behaviors to Facade 262 Removing Access and Features When No Longer Needed 263 Test-Driving Behaviors in the Facade Database 264 Exposing Legacy Behaviors 265 Another Way to Do It 265 New Behaviors 266 Summary 266 Chapter 14 Variations 269 Having a Class Is Important-Implementation Is Not 270 Scenario: Skipping Steps 270 Problem 271 Solution 272 The Right Amount of Work 273 Scenario: Deviations 274 Problem 274 Solution 275 Solution Applied 277 Common Solution 281 Summary 281 Chapter 15 Other Applications 283 XML 284 Encapsulation 284 XSD Schemas 284 XSLT Transitions 286 Transition Test XSLT Changes 287 File Systems and Other Object Directories 288 Transition Test File System Manipulations 289 Shell Script Transitions 291 Data Objects 292 Class Definitions Are Schemas 292 Transition Test the Ugrader Class 294 Code Transitions 296 Summary and Send Off 300 Index 301