Your Code as a Crime Scene

Foreword by Michael Feathers . . . . . . . . ix
Acknowledgments . . . . . . . . . . . xi
1. Welcome! . . . . . . . . . . . . . . 1
About This Book 1
Optimize for Understanding 2
How to Read This Book 4
Toward a New Approach 6
Get Your Investigative Tools 7
Part I — Evolving Software
2. Code as a Crime Scene . . . . . . . . . . 13
Meet the Problems of Scale 13
Get a Crash Course in Offender Profiling 15
Profiling the Ripper 16
Apply Geographical Offender Profiling to Code 17
Learn from the Spatial Movement of Programmers 18
Find Your Own Hotspots 22
3. Creating an Offender Profile . . . . . . . . . 23
Mining Evolutionary Data 23
Automated Mining with Code Maat 26
Add the Complexity Dimension 28
Merge Complexity and Effort 30
Limitations of the Hotspot Criteria 30
Use Hotspots as a Guide 31
Dig Deeper 33
4. Analyze Hotspots in Large-Scale Systems . . . . . 35
Analyze a Large Codebase 35
Visualize Hotspots 38
Explore the Visualization 40
Study the Distribution of Hotspots 41
Differentiate Between True Problems and False Positives 45
5. Judge Hotspots with the Power of Names . . . . . 47
Know the Cognitive Advantages of Good Names 47
Investigate a Hotspot by Its Name 50
Understand the Limitations of Heuristics 52
6. Calculate Complexity Trends from Your Code’s Shape . . 55
Complexity by the Visual Shape of Programs 55
Learn About the Negative Space in Code 57
Analyze Complexity Trends in Hotspots 59
Evaluate the Growth Patterns 63
From Individual Hotspots to Architectures 64
Part II — Dissect Your Architecture
7. Treat Your Code As a Cooperative Witness . . . . . 67
Know How Your Brain Deceives You 68
Learn the Modus Operandi of a Code Change 71
Use Temporal Coupling to Reduce Bias 72
Prepare to Analyze Temporal Coupling 76
8. Detect Architectural Decay . . . . . . . . . 77
Support Your Redesigns with Data 77
Analyze Temporal Coupling 78
Catch Architectural Decay 83
React to Structural Trends 87
Scale to System Architectures 89
9. Build a Safety Net for Your Architecture . . . . . . 91
Know What’s in an Architecture 91
Analyze the Evolution on a System Level 93
Differentiate Between the Level of Tests 94
Create a Safety Net for Your Automated Tests 99
Know the Costs of Automation Gone Wrong 103
Contents • vi
10. Use Beauty as a Guiding Principle . . . . . . . 105
Learn Why Attractiveness Matters 105
Write Beautiful Code 107
Avoid Surprises in Your Architecture 108
Analyze Layered Architectures 111
Find Surprising Change Patterns 113
Expand Your Analyses 116
Part III — Master the Social Aspects of Code
11. Norms, Groups, and False Serial Killers . . . . . 121
Learn Why the Right People Don’t Speak Up 122
Understand Pluralistic Ignorance 124
Witness Groupthink in Action 127
Discover Your Team’s Modus Operandi 128
Mine Organizational Metrics from Code 132
12. Discover Organizational Metrics in Your Codebase . . . 133
Let’s Work in the Communication Business 133
Find the Social Problems of Scale 135
Measure Temporal Coupling over Organizational Boundaries 138
Evaluate Communication Costs 141
Take It Step by Step 145
13. Build a Knowledge Map of Your System . . . . . . 147
Know Your Knowledge Distribution 147
Grow Your Mental Maps 152
Investigate Knowledge in the Scala Repository 155
Visualize Knowledge Loss 158
Get More Details with Code Churn 161
14. Dive Deeper with Code Churn . . . . . . . . 163
Cure the Disease, Not the Symptoms 163
Discover Your Process Loss from Code 164
Investigate the Disposal Sites of Killers and Code 168
Predict Defects 171
Time to Move On 174
15. Toward the Future . . . . . . . . . . . 175
Let Your Questions Guide Your Analysis 175
Take Other Approaches 177
Contents • vii
Let’s Look into the Future 181
Write to Evolve 182
A1. Refactoring Hotspots . . . . . . . . . . 183
Refactor Guided by Names 183
Bibliography . . . . . . . . . . . . 187
Index . . . . . . . . . . . . . . 191
Contents • viii