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Ruby, tests, code review and automation.

Christophe Philemotte, BRUG 5 Nov 2013

About me

  • Developer
  • founder and C?O of 8th Color
  • PullReview

Ruby is Dynamic typing

x = false
x = 3
x = 'this is a string'

and strong typing

x = '3'
x = x + 3
# TypeError: no implicit conversion of Fixnum into String

Ruby is Duck typing

class Duck
  def quack
    puts 'Quaaaaaack!'
  end
end

class Person
  def quack
    puts 'The person imitates a duck.'
  end
end

donald = Duck.new
john = Person.new
duck.quack
john.quack

# Quaaaaaack!
# The person imitates a duck.

from Wikipedia

Getting Weak Typing with Duck Typing

class Fixnum
  alias_method :old_plus, :+

  def new_plus(other)
    return self.to_s + other if other.kind_of? String
    self.old_plus(other)
  end

  alias_method :+, :new_plus

end

x = '3'
y = 3 + x

With Great Freedom

  • Meaningfull & Concise
  • Flexible & Contract Based
  • Easy DI

Comes Great Risk

  • Error Only at Runtime
  • No Static Interface
  • You shouldn't care of the type, but ...

How to Mitigate?

  • Writing Tests
  • Code Review
  • Automation

Tests Benefits

  • Check the Contract and the User Story
  • Reliable Changes through Time
  • Documentation of the Code
  • Guards against Regression and Edge Cases
  • Speed the dev Cycle

Tests Framework

  • Test:Unit
  • MiniTest
  • Rspec
  • Cucumber

Continuous Integration

kitty

Continuous Integration

  • Jenkins
  • Travis
  • CodeShip
  • Semapore

Code Review is a Discussion

discussion

Code Review Benefits

  • Knowledge Sharing
  • Mutual Education in the Team
  • Bug Detection before Shipping
  • Readability and Consistency Improvement
  • CoOwnership Reinforcement
  • Shorter Dev/Test Cycles

Code Review Benefits

60% of all issues raised in the code inspections are not problems that could have been uncovered by latter phases of testing or field usage because they have little or nothing to do with the visible execution behavior of the software. (H. Siy and L. Votta 2001)

Code Review Tools

  • GitHub PullRequest
  • Gerrit
  • Collaborator
  • Crucible

Automated Code Review Benefits

Automation is necessary. It is common to take a sort of smug satisfaction in reports of colossal failures of automatic systems, but for every failure of automation, the failures of humans are legion.

Automated Code Review Benefits

Exhortations to "write better code" plans for more code reviews, pair programming, and so on just don’t cut it, especially in an environment with dozens of programmers under a lot of time pressure. The value in catching even the small subset of errors that are tractable to static analysis every single time is huge. John Carmack, 2011

Automated Code Review Benefits

  • Short Feedback Time and NOW!
  • None Emotional Influences
  • Tracking Progress
  • Reproducible, Invariable
  • Don't Waste Peer Time, Spent time on Complicated.

Automated Code Review Tools

  • Ruby Warning (Linter)
  • Flog (Complexity)
  • Flay (Duplication)
  • Excellent (a Medley)
  • Rails Best Practices (specific to Rails)
  • Brakeman (Security)
  • Rubocop (Style and Linter)
  • Yard (Documentation)

Automated Code Review Tools

  • CodeClimate
  • PullReview

Review

Conclusion

  • Start right now
  • Setup one thing at a time with your team
  • It's an incremental and team process
  • There are complementary strategies