Fighting Code Smells #FrozenRails

Ruby code quality tool overview

Transcript

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 autotest cucumber rspec simplecov rcov reek flay dust pelusa roodi flog metrics_fu heckle Static Runtime
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. en_Dal dennis.ushakov@jetbrains.com denofevil