Escaping The Tar Pit at RubyConf 2019

Presentation about avoiding and escaping the tar pit. The case for a new metric: The StinkScore.

The StinkScore is a combination of smells; complexity; and code coverage. You can use it as a compass to get out of the tar pit and gradually (and measurably) pay off technical debt. 🤓❤️

Presented at RubyConf in Nashville (Nov 19th, 2019)

Transcript

1. Escaping The Tar Pit Ernesto Tagwerker (@etagwerker) RubyConf, November 2019
2. ! Hi, I’m from Argentina I live in Philadelphia # I ❤ Open Source
3. Founder & Software Engineer @OmbuLabs
4. Founder & Software Engineer @fastrubyio
5. Open Source Maintainer database_cleaner; bundler-leak; next_rails
6. Inspiration
7. Chapter 1: The Tar Pit
8. “The fiercer the struggle, the more entangling the tar, and no beast is so strong or so skillful but that they ultimately sink.” Fred Brooks
9. “Large-system programming has over the past decade been such a tar pit, and many great and powerful beasts have thrashed violently in it.” Fred Brooks
10. We are in the tar pit or trying to avoid it
12. Tar Pit Symptoms > Projects running over budget
13. Tar Pit Symptoms > Projects running over budget > Taking forever to ship small changes
14. Tar Pit Symptoms > Projects running over budget > Taking forever to ship small changes > Sacrificing quality, increasing tech debt
16. Part 1: How to avoid the tar pit
17. “THAT’D BE GREAT” BOSS: “IF YOU COULD COME IN ON THIS GREAT, LEGACY PROJECT AND MAINTAIN IT FROM NOW ON…”
18. “THAT’D BE GREAT” CLIENT: “IF YOU COULD COME IN ON THIS GREAT, LEGACY PROJECT AND MAINTAIN IT FROM NOW ON…”
19. CLIENT: “HOW LONG IS IT GOING TO TAKE?”
20. “BECAUSE I NEED IT BY END OF DAY TODAY” CLIENT: “HOW LONG IS IT GOING TO TAKE?”
21. How can we quickly assess code quality?
22. Part 2: How to get out of the tar pit
23. How can we gradually pay off technical debt?
24. Part 1: Avoiding the tar pit
26. “It can’t be that hard. It’s a Ruby project.”
27. How can we quickly assess code quality?
28. Assessing Quality ✅ Paid Services ✅ Open Source Gems
29. Assessing Quality ✅ Paid Services ➡ Open Source Gems
30. Open Source Gems ✅ Static code analysis
31. Open Source Gems ✅ Static code analysis ✅ Code coverage
32. Open Source Gems ✅ Static code analysis ✅ Code coverage ✅ Code smells
33. What is software quality anyway?
34. There are hundreds of definitions
35. “The degree to which a system, component, or process meets implicit and explicit requirements.” IEEE
36. “It works as expected.”
37. “It works as expected and it is not a PITA to maintain it.”
38. ISO 9126-1 Software Quality Model ✅ Reliability ✅ Usability ✅ Efficiency ✅ Maintainability ✅ Portability
39. ISO 9126-1 Software Quality Model ✅ Reliability ✅ Usability ✅ Efficiency ➡ Maintainability ✅ Portability
40. Maintainability
41. Maintainability 1. Code Coverage
42. Maintainability 1. Code Coverage 2. Code Quality
43. Code Coverage SimpleCov (github.com/colszowka/simplecov)
44. Code Coverage # Gemfile group :test do gem "simplecov", require: false end
45. Code Coverage # spec/spec_helper.rb if ENV["COVERAGE"] == "true" require 'simplecov' SimpleCov.start do add_group "Models", "models" add_filter "/spec/" track_files "**/*.rb" end end
46. Code Coverage $ COVERAGE=true rspec
47. Code Coverage
48. Code Quality n options
49. Code Quality n options (flog; flay; reek; churn; RubyCritic; MetricFu; attractor; rubocop; fukuzatsu; turbulence; …)
50. Code Quality RubyCritic (github.com/whitesmith/rubycritic)
51. Churn
52. Churn git
53. Churn $ git log --follow --format=%h default.rb | cat 573c8f5 2ccc5b8 b447bc3
54. Churn $ git log --follow --format=%h default.rb | cat 573c8f5 2ccc5b8 b447bc3 # Churn Count = 3
55. Complexity
56. Complexity flog
57. Complexity $ flog foo.rb => 10.8: flog total
58. Complexity class Foo def yay # 10.8 = a = eval "1+1" # 1.2 + 6.0 + if a == 2 # 1.2 + 1.2 + puts "yay" # 1.2 end end end
59. Complexity $ flog foo.rb => 10.8: flog total
60. Churn vs. Complexity
61. Churn Complexity 50 0 1 100_000
62. Churn Complexity 100 0 1 100_000 user.rb (changed: 2 times; complexity: 100_000 )
63. Churn Complexity 100 0 1 100_000 user.rb (changed: 27 times; complexity: 100)
64. Code Quality $ gem install rubycritic
65. Code Quality $ rubycritic
67. GPA Pie Graph Complexity (flog) Code Smells (reek)
68. Churn vs. Complexity Churn (SCM) Complexity (flog)
69. 100 0 1 100_000 Complexity Churn
70. 100 0 1 100_000 Complexity Churn
71. 100 0 1 100_000 “Welcome to the good place.” ❤ Complexity Churn
72. 100 0 1 100_000 No one understands these files but they work. So don’t change them. Complexity Churn
73. 100 0 1 100_000 “[…], if the code never changes, it's not costing us money.” Sandi Metz Complexity Churn
74. 100 0 1 100_000 Everybody understands these files but you need to change them often Complexity Churn
75. 100 0 1 100_000 Complexity Churn These modules are complex and change a lot… '
76. 100 0 1 100_000 Complexity Churn “Sometimes a class becomes so complex that refactoring seems too difficult.” Michael Feathers
77. Are you getting into a tar pit, is it a dumpster fire, or have you found a project which is easy to maintain?
78. 100 0 1 100_000 Welcome to the tar pit. Complexity Churn
79. Maintainability 1. Code Coverage (SimpleCov) 2. Code Quality (RubyCritic)
80. Signal #1 Code Coverage
81. Signal #2 Complexity
82. Coverage & Complexity
83. But what if we could calculate a new signal that combines both?
84. Signal #3 StinkScore
85. StinkScore = f(code_quality, code_coverage)
86. StinkScore = f(code_smells, code_complexity, code_coverage)
87. Files which lack tests should be penalized
88. foo.rb complexity: 10 smells: 10 smell points: 100 (10*10)
89. bar.rb complexity: 10 smells: 10 smell points: 100 (10*10)
90. foo.rb complexity: 10 smells: 10 smell points: 100 (10*10) bar.rb complexity: 10 smells: 10 smell points: 100 (10*10)
91. foo.rb and bar.rb are equally stinky
92. foo.rb complexity: 10 smells: 10 code_coverage: 0 stink_score: 10,000 (10*10)*100
93. bar.rb complexity: 10 smells: 10 code_coverage: 100 stink_score: 100 (10*10)*1
94. foo.rb complexity: 10 smells: 10 code_coverage: 0 stink_score: 10,000 (10*10)*100 bar.rb complexity: 10 smells: 10 code_coverage: 100 stink_score: 100 (10*10)*1
95. foo.rb is considerably stinkier than bar.rb
96. How can we automate this analysis?
97. Skunk A Stink Score Calculator (github.com/fastruby/skunk)
98. Skunk $ gem install skunk
99. Skunk $ skunk
102. Skunk $ skunk ... StinkScore Total: 13231.069999999996 Modules Analysed: 71 StinkScore Average: 186.3530985915493 Worst StinkScore: 2401.75 (lib/rubycritic/source_control_systems/git.rb)
103. Skunk $ skunk ... StinkScore Total: 13231.069999999996 Modules Analysed: 71 StinkScore Average: 186.3530985915493 Worst StinkScore: 2401.75 (lib/rubycritic/source_control_systems/git.rb)
104. RubyCritic module RubyCritic class AnalysedModule def cost smells.map(&:cost).inject(0.0, :+) + (complexity / COMPLEXITY_FACTOR) end end end
105. RubyCritic module RubyCritic class AnalysedModule def cost smells.map(&:cost).inject(0.0, :+) + # From Reek (complexity / COMPLEXITY_FACTOR) end end end
106. RubyCritic module RubyCritic class AnalysedModule def cost smells.map(&:cost).inject(0.0, :+) + # From Reek (complexity / COMPLEXITY_FACTOR) # From Flog end end end
107. Skunk module RubyCritic class AnalysedModule def stink_score return cost if perfect_coverage? cost * (PERFECT_COVERAGE - coverage.to_i) end end end
108. Skunk module RubyCritic class AnalysedModule def stink_score return cost if perfect_coverage? cost * (PERFECT_COVERAGE - coverage.to_i) # Penalty Factor = 100% - 20% => 80 end end end
109. Skunk Warning > skunk-v0.3.1
110. Skunk Warning > skunk-v0.3.1 > COVERAGE=TRUE rake test
111. Skunk Warning > skunk-v0.3.1 > COVERAGE=TRUE rake test > feedback wanted
112. Maintainability 1. Code Coverage (SimpleCov) 2. Code Quality (RubyCritic) 3. StinkScore (Skunk)
113. You are here:
114. Part 2: Getting out of the tar pit
115. So, where do we begin?
116. removing files will decrease our stink_score
117. Find Dead Code Coverband (github.com/danmayer/coverband)
119. refactoring complex files will decrease our stink_score
120. 100 0 1 100_000 Complexity Churn “Here be dragons. These modules are complex and change a lot…” '
121. 100 0% 1 100_000 Complexity Churn “Great candidates for refactoring (paying technical debt!)” #
122. Churn vs. Complexity is not enough to prioritize
123. Stink Score Table
124. Refactor These Files:
125. Refactor These Files:
126. 100 0 1 100_000 Complexity Churn git.rb
127. 100 0 1 100_000 Complexity Churn git_calculator.rb git_fetcher.rb refactor! git.rb
128. 100 0 1 100_000 Complexity Churn git_calculator.rb git_fetcher.rb
129. Skunk $ skunk -b master Base branch (master) average stink score: 79.78 Feature branch (refactor/git) average stink score: 71.79
130. Skunk $ skunk -b master Base branch (master) average stink score: 79.78 Feature branch (refactor/git) average stink score: 71.79 10% better ( ( (
131. writing tests for our app will decrease our stink_score
132. Stink Score Table
133. Write Tests Here:
134. Skunk* $ skunk -b master Base branch (master) average stink score: 79.78 Feature branch (refactor/git) average stink score: 71.79
135. Time StinkScore Average 100 (days) 0 1 100
136. stink_score Code Coverage; Complexity; and Smells
137. stink_score Your compass to get out of the tar pit
138. Thank you! @etagwerker 138 Thank you! ‣ github.com/fastruby/skunk ‣ @OmbuLabs ‣ @fastrubyio ‣ @etagwerker
139. Resources 1. https://github.com/whitesmith/rubycritic 2.https://github.com/colszowka/simplecov 3.https://github.com/metricfu/metric_fu 4.https://github.com/julianrubisch/attractor 5.https://www.fastruby.io/blog/ruby/quality/code-quality-ruby-gems.html 6.https://www.reddit.com/r/ruby/comments/2bq092/rubycritic/ 7.http://jakescruggs.blogspot.com/2008/08/whats-good-flog-score.html 8.http://ruby.sadi.st/Flog.html 9.http://ruby.sadi.st/Flay.html 10.https://github.com/makaroni4/sandi_meter 11.https://www.fastruby.io/blog/code-quality/intruducing-skunk-stink-score- calculator.html
140. Resources 1.https://codeclimate.com/blog/deciphering-ruby-code-metrics/ 2.https://www.stickyminds.com/article/getting-empirical-about-refactoring 3.https://www.sandimetz.com/blog/2017/9/13/breaking-up-the-behemoth 4.https://github.com/troessner/reek 5.https://github.com/seattlerb/flay 6.https://github.com/seattlerb/flog 7.http://www.sqa.net/iso9126.html 8.https://www.slideshare.net/mscottford/important-metrics-for-measuring-code-health 9.https://dilbert.com/strip/2006-12-08 10.https://www.fastruby.io/blog/ruby/quality/code-quality-ruby-gems.html 11.https://www.fastruby.io/blog/code-quality/code-coverage/rubycritic-4-2-0- simplecov-support.html