Don’t Hang Me Out To DRY

Close your eyes and imagine the perfect codebase to work on. I bet you’ll say it has complete test coverage. It’s fully-optimized, both in terms of performance and architectural design. And, of course, it contains only DRY code. Surely we can all agree that this is an aspirational situation. But...do we really want that?

Don’t get me wrong; these qualities are all beneficial. However, if we also think we should value everything in moderation, when should we push back on these ideals? What problems can they introduce? Let’s talk about the exceptions to some of the “rules” we all hold dear.

Transcript

1. Don’t Hang Me Out to DRY Kevin Murphy @kevin_j_m
2. Don’t Hang Me Out to DRY Kevin Murphy @kevin_j_m
3. @kevin_j_m vory Tower
 nnovation TechnologY
4. @kevin_j_m T T
5. @kevin_j_m T
6. @kevin_j_m T our code has
7. @kevin_j_m T Make work
8. @kevin_j_m T Make work ☂
9. @kevin_j_m T Make T work Make right
10. @kevin_j_m T Make right ❌
11. @kevin_j_m T Make T T work Make Make right fast
12. @kevin_j_m T Make fast
13. @kevin_j_m T Make T T work Make Make right fast
14. @kevin_j_m
16. @kevin_j_m Kevin Murphy
17. @kevin_j_m T
18. @kevin_j_m Should see 4 testimonials today, but only 3 are seen.
19. @kevin_j_m def number_testimonials if mercury_retrograde? 4 elsif full_moon? 3 elsif tuesday? 2 else coin_flip end end
20. @kevin_j_m def number_testimonials if mercury_retrograde? 4 elsif full_moon? 3 elsif tuesday? 2 else coin_flip end end
21. @kevin_j_m Farmer’s Almanac Mercury in Retrograde OCT 31 NOV 20
22. @kevin_j_m Code Coverage
23. @kevin_j_m
24. @kevin_j_m it "shows 4 testimonials if mercury is in retrograde" do end
25. @kevin_j_m it "shows 4 testimonials if mercury is in retrograde" do allow(Mercury).to receive(:in_retrograde?).and_return(true) end
26. @kevin_j_m it "shows 4 testimonials if mercury is in retrograde" do allow(Mercury).to receive(:in_retrograde?).and_return(true) display = TestimonialDisplay.new end
27. @kevin_j_m it "shows 4 testimonials if mercury is in retrograde" do allow(Mercury).to receive(:in_retrograde?).and_return(true) display = TestimonialDisplay.new expect(display.number_testimonials).to eq 4 end
28. @kevin_j_m
29. @kevin_j_m class Mercury def self.in_retrograde?(date) end end
30. @kevin_j_m class Mercury def self.in_retrograde?(date) false end end
31. @kevin_j_m
32. @kevin_j_m Coverage is insufficient
33. @kevin_j_m TDD
34. @kevin_j_m Pair Programming
35. @kevin_j_m Mutation Testing
36. @kevin_j_m Code Review
37. @kevin_j_m QA
38. @kevin_j_m '
39. @kevin_j_m Coverage is insufficient
40. @kevin_j_m Coverage as a goal
41. @kevin_j_m Randomized with seed 46917 .F.. Failures: 1) TestimonialDisplay#number_testimonials will show 0 or 1 testimonial if no other conditions are met Failure/Error: expect(results.uniq).to match_array [0, 1] expected collection contained: [0, 1] actual collection contained: [1] the missing elements were: [0]
42. @kevin_j_m def number_testimonials if mercury_retrograde? 4 elsif full_moon? 3 elsif tuesday? 2 else coin_flip end end
43. @kevin_j_m def coin_flip rand(2) end
44. @kevin_j_m it "will show 0 or 1 testimonial" do end
45. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) end
46. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] end
47. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new end
48. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do end end
49. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do 2.times do end end end
50. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do 2.times do results << display.number_testimonials end end end
51. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do 2.times do results << display.number_testimonials end end expect(results.uniq).to match_array [0, 1] end
52. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do 2.times do results << display.number_testimonials end end expect(results.uniq).to match_array [0, 1] end
53. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do 2.times do results << display.number_testimonials end end expect(results.uniq).to match_array [0, 1] end
54. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) results = [] display = TestimonialDisplay.new travel_to waning_monday do 200.times do results << display.number_testimonials end end expect(results.uniq).to match_array [0, 1] end
55. @kevin_j_m it "will show 0 or 1 testimonial" do waning_monday = Date.new(2019, 9, 16) display = TestimonialDisplay.new travel_to waning_monday do expect(results.uniq).to be_in [0, 1] end end
56. @kevin_j_m Vanity metric?
57. @kevin_j_m
58. @kevin_j_m Coverage is a signal
59. @kevin_j_m
60. @kevin_j_m
61. @kevin_j_m
62. @kevin_j_m
63. @kevin_j_m
64. @kevin_j_m Coverage Consideration Total Cost of Ownership
65. @kevin_j_m T
66. @kevin_j_m +
67. @kevin_j_m ☑ Dark Dungeon API Access Keys should follow same convention
68. @kevin_j_m it "does not provide a company key" do end
69. @kevin_j_m it "does not provide a company key" do generator = AccessKeyGenerator.new end
70. @kevin_j_m it "does not provide a company key" do generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) end
71. @kevin_j_m it "does not provide a company key" do generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) expect(key.match?(COMPANY_REGEX)).not_to eq true end
72. @kevin_j_m it "appends the user id if the user's id is odd" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :user, user_id: 1) expect(key).to end_with("-1") end it "does not provide a company key" do generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) expect(key.match?(COMPANY_REGEX)).not_to eq true end it "raises an exception if it doesn't understand the accessor type" do generator = AccessKeyGenerator.new expect { generator.access_key(accessor_type: :foo) } .to raise_error UnknownAccessorType end end end
73. @kevin_j_m it "appends the user id if the user's id is odd" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :user, user_id: 1) expect(key).to end_with("-1") end it "does not provide a company key" do generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) expect(key.match?(COMPANY_REGEX)).not_to eq true end it "raises an exception if it doesn't understand the accessor type" do generator = AccessKeyGenerator.new expect { generator.access_key(accessor_type: :foo) } .to raise_error UnknownAccessorType end end end
74. @kevin_j_m RSpec.describe AccessKeyGenerator do UUID_REGEX = /[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}/ COMPANY_REGEX = /CO-[0-9a-fA-F]{8}/ describe "#access_key" do it "provides a base-64 encoded key if the key is for an acquired company" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :company, acquired_company: true) expect(key).to eq Base64.strict_encode64(Base64.decode64(key)) end it "creates an ivory tower company access key if it's a company not acquired" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :company, acquired_company: false) expect(key.match?(COMPANY_REGEX)).to eq true end it "does not provide a full UUID if the key is for a company" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :company)
75. @kevin_j_m RSpec.describe AccessKeyGenerator do UUID_REGEX = /[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}/ COMPANY_REGEX = /CO-[0-9a-fA-F]{8}/ describe "#access_key" do it "provides a base-64 encoded key if the key is for an acquired company" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :company, acquired_company: true) expect(key).to eq Base64.strict_encode64(Base64.decode64(key)) end it "creates an ivory tower company access key if it's a company not acquired" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :company, acquired_company: false) expect(key.match?(COMPANY_REGEX)).to eq true end it "does not provide a full UUID if the key is for a company" do generator = AccessKeyGenerator.new key = generator.access_key(accessor_type: :company)
76. @kevin_j_m DRY Code Don’t Repeat Yourself
77. @kevin_j_m DAMP Code Descriptive And Meaningful Phrases
78. @kevin_j_m it "does not provide a company key" do generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) expect(key.match?(COMPANY_REGEX)).not_to eq true end
79. @kevin_j_m it "does not provide a company key" do company_regex = /CO-[0-9a-fA-F]{8}/ generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) expect(key.match?(COMPANY_REGEX)).not_to eq true end
80. @kevin_j_m it "does not provide a company key" do company_regex = /CO-[0-9a-fA-F]{8}/ generator = AccessKeyGenerator.new key = generator.access_key(accessor: :user, user_id: 0) expect(key.match?(company_regex)).not_to eq true end
81. @kevin_j_m T
82. @kevin_j_m class AccessKeyGenerator def access_key(accessor:, user_id: nil) if accessor == :company "CO-#{SecureRandom.hex(8)}" elsif accessor == :user uuid = SecureRandom.uuid user_id.odd? ? uuid << “-#{user_id}" : uuid end end end
83. @kevin_j_m class AccessKeyGenerator def access_key(accessor:, acquired_co: nil, user_id: nil) if accessor == :company "CO-#{SecureRandom.hex(8)}" elsif accessor == :user uuid = SecureRandom.uuid user_id.odd? ? uuid << “-#{user_id}" : uuid end end end
84. @kevin_j_m class AccessKeyGenerator def access_key(accessor:, acquired_co: nil, user_id: nil) if accessor == :company if acquired_co SecureRandom.base64 else “CO-#{SecureRandom.hex(8)}” end elsif accessor == :user uuid = SecureRandom.uuid user_id.odd? ? uuid << “-#{user_id}" : uuid end end end
85. @kevin_j_m DRY Code?
86. @kevin_j_m class User < ApplicationRecord def generate_access_key SecureRandom.uuid end end
87. @kevin_j_m class Company < ApplicationRecord def generate_access_key SecureRandom.uuid end end
88. @kevin_j_m
89. @kevin_j_m class AccessKeyGenerator def access_key SecureRandom.uuid end end
90. @kevin_j_m class AccessKeyGenerator def access_key(accessor:, user_id: nil) if accessor == :company "CO-#{SecureRandom.hex(8)}" elsif accessor == :user uuid = SecureRandom.uuid user_id.odd? ? uuid << “-#{user_id}" : uuid end end end
91. @kevin_j_m WET Code Write Everything Twice
92. @kevin_j_m
93. @kevin_j_m class User < ApplicationRecord def generate_access_key SecureRandom.uuid end end
94. @kevin_j_m class User < ApplicationRecord def generate_access_key SecureRandom.uuid end end class Company < ApplicationRecord def generate_access_key SecureRandom.uuid end end
95. @kevin_j_m class User < ApplicationRecord def generate_access_key if id.odd? "#{SecureRandom.uuid}-#{id}" else SecureRandom.uuid end end end
96. @kevin_j_m class User < ApplicationRecord def generate_access_key if id.odd? "#{SecureRandom.uuid}-#{id}" else SecureRandom.uuid end end end class Company < ApplicationRecord def generate_access_key if acquisition? SecureRandom.base64 else "CO-#{SecureRandom.hex(8)}" end end end
97. @kevin_j_m DRY Consideration Flexibility
98. @kevin_j_m T
99. @kevin_j_m Passing “15” to API provides wrong result
100. @kevin_j_m Performant Code
101. @kevin_j_m Rust
102. @kevin_j_m gem 'helix-rails', '~> 0.5.0'
103. @kevin_j_m def generate(bound: i32)
104. @kevin_j_m def generate(bound: i32) -> Vec<String> { }
105. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); }
106. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { } }
107. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { }) } }
108. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), }) } }
109. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), }) } }
110. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), }) } }
111. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), (2, 4) => "Buzz".to_string(), }) } }
112. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), (2, 4) => "Buzz".to_string(), (_, _) => x.to_string(), }) } }
113. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), (2, 4) => "Buzz".to_string(), (_, _) => x.to_string(), }) } results }
114. @kevin_j_m FBAAS
115. @kevin_j_m FBAAS FizzBuzz As A Service
116. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), (2, 4) => "Buzz".to_string(), (_, _) => x.to_string(), }) } results }
117. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), (2, 4) => "Buzz".to_string(), (_, _) => x.to_string(), }) } results }
118. @kevin_j_m def generate(bound: i32) -> Vec<String> { let mut results = Vec::new(); for x in 1..(bound+1) { results.push(match(x % 3, x % 5) { (0, 0) => "FizzBuzz".to_string(), (0, _) => "Fizz".to_string(), (_, 0) => "Buzz".to_string(), (_, _) => x.to_string(), }) } results }
119. @kevin_j_m Performant Consideration Weigh observed behavior & maintenance
120. @kevin_j_m T Make T T work Make Make right fast
121. @kevin_j_m T Make work for confidence, not metrics
122. @kevin_j_m T Make right knowing “right” is subjective
123. @kevin_j_m T Make fast when you know it’s warranted
124. @kevin_j_m https://www.thegnar.co/rubyconf https://github.com/kevin-j-m/ivory-tower T
125. @kevin_j_m https://www.thegnar.co/rubyconf