1. Fighting Code Smells
ruby code analysis tools
Dennis Ushakov

2. Pareto Principle
• 20%
Write new code
• 80%
Modify existing code

3. Does This Smell?
a = something.valid?
if (a.to_s == "true")
# code here
end

4. Does This Smell?
def has_currency_rate?
val = false
if currency.id == company.currency.id or rate.blank?
else
val = true
end
val
end

5. Does This Smell?
class FinancialEventObserver < ActiveRecord::Observer
observe Payment, Invoice
def before_save(model)
event = nil
if model.class == Payment
if model.new_record?
event = FinancialEvent.new(:event => FinancialEvent::Event::PAYMENT_INVOICE,
:arguments => {:client_name => model.invoice.client.short_name, :invoice_number =>
model.invoice.invoice_number},
:company_id=>model.invoice.client.company.id)
end
elsif model.class == Invoice
i = Invoice.find_by_id model.id
if model.new_record? or i.status != model.status
if model.status == Invoice::Status::ESTIMATE
event = FinancialEvent.new(:event => FinancialEvent::Event::ESTIMATE_SEND,
:arguments => {:client_name => model.client.short_name, :invoice_number => model.invoice_number},
:company_id=>model.client.company.id)
elsif model.status == Invoice::Status::APPROVED
event = FinancialEvent.new(:event => FinancialEvent::Event::ESTIMATE_APPROVED,
:arguments => {:client_name => model.client.short_name, :invoice_number => model.invoice_number},
:company_id=>model.client.company.id)
elsif model.status == Invoice::Status::REJECTED
event = FinancialEvent.new(:event => FinancialEvent::Event::ESTIMATE_REJECTED,
:arguments => {:client_name => model.client.short_name, :invoice_number => model.invoice_number},
:company_id=>model.client.company.id)
elsif model.status == Invoice::Status::SEND
event = FinancialEvent.new(:event => FinancialEvent::Event::INVOICE_SEND,
:arguments => {:client_name => model.client.short_name, :invoice_number => model.invoice_number},
:company_id=>model.client.company.id)
end
elsif !model.new_record? and i.state != model.state
if model.state == Invoice::State::DELETED
event = FinancialEvent.new(:event => FinancialEvent::Event::INVOICE_DELETED,
:arguments => {:invoice_number => model.invoice_number},
:company_id=>model.client.company.id)
end
end
end
event.eventable = model.requester unless event.blank?
event.save unless event.blank?

6. Code That Smells
• Runtime errors
• Runtime warnings
• Dead code
• Copy/paste
• Complex method bodies
• Code style violations
• Framework pattern violations

7. Code Quality Tools
Static Runtime
flay roodi rspec
metrics_fu rcov
dust simplecov
heckle reek autotest
pelusa cucumber
flog

8. Static Tools
• Inspect your code without launching it
• 100% side effects free
• Challenging to implement
• Rails DSL magic kills ‘em

9. Reek
• Class, module, method, identifier names
• Using is_a?, kind_of? instead of duck typing
• Code duplicates
• Large classes and methods
• Nested iterators

10. Flog
• Uses ABC metrics system
• Assignment
• Branches
• Conditions
• |ABC| = √(A²+B²+C²)
• Consider revising most
painful methods

11. Flay
• Analyzes code duplicates
• Ignores identifier/
constants names
• Consider refactoring
code that’s reported

12. Roodi
• Assignments in conditions
• Case blocks without else
• Large classes, modules and methods
• Naming conventions
• Cyclomatic complexity

13. metrics_fu/metrical
Provides aggregate results for
• Flay
• Flog
• Reek
• Roodi

14. Runtime Tools
• Inspect your code by launching it
• 100% follow the way Ruby works
• Cope well with DSL magic
• May have side effects
• Works until the very first failure

15. Runtime Tools
• Code testing
• Test::Unit/MiniTest
• RSpec/Cucumber
• Autotest/CI
• Code coverage
• RCov/SimpleCov
• Heckle

16. Heckle
• Changes code
• if → unless
• Calls are changed
• Numbers are changed
• Runs tests
• At least one test should
fail after change

17. RubyMine
• Static analysis
• On-the-fly inspections with quickfixes
• Understands Rails DSLs
• Code duplication
• Dynamic analysis tools integration
• Graphical representation
• Autotest simulation
• Stacktrace navigation

18. Refactorings
• Rename
• Extract
• Method
• Class/Module
• Variable/Parameter

19. Morale
• Use static analysis
tools
• Don’t forget to test
• Try RubyMine
http://jetbrains.com/
ruby

20. dennis.ushakov@jetbrains.com
en_Dal
denofevil