how to rate a Rails application

How to rate a Rails application Elise Huard @elise_huard http://jabberwocky.eu Sunday 30 May 2010

Acquisition Sunday 30 May 2010

Maintenance Sunday 30 May 2010

Where to Start ? Sunday 30 May 2010

Try the app Björn Söderqvist on Flickr Sunday 30 May 2010

Rails version Sunday 30 May 2010

plugins and gems Photo Lex on Flickr Sunday 30 May 2010

Sunday 30 May 2010

Run Tests Sunday 30 May 2010

Lots of code Sunday 30 May 2010

config/routes.rb match ‘/’, :to => ‘root#index’ match ‘root’, :to => ‘root#index’ namespace :admin do resources :grids do resources :nodes resources :edges do collection do post :all post :update_all end end resources :walkers end end resources :nodes, :only => [:show,:new,:create,:destroy] do put :directions, :on => :collection end resources :walkers, :only => [:show,:new,:create,:destroy] do get :select, :on => :collection end resources :itineraries, :only => [:show] Sunday 30 May 2010 map.four_oh_four '*path' , :controller => 'four_oh_fours'

models railroad -M | dot Tpng > models.png rubymine ctrl-alt-D Sunday 30 May 2010

names “There are only two hard things in Computer Science: cache invalidation and naming things” Phil Karlton Sunday 30 May 2010

Metrics: Know thine Tools docman on ﬂickr Sunday 30 May 2010

LOC rake stats +----------------------+-------+-------+---------+---------+-----+-------+ | Name | Lines | LOC | Classes | Methods | M/C | LOC/M | +----------------------+-------+-------+---------+---------+-----+-------+ | Controllers | 2702 | 2150 | 36 | 158 | 4 | 11 | | Helpers | 358 | 303 | 0 | 22 | 0 | 11 | | Models | 1358 | 1104 | 30 | 117 | 3 | 7 | | Libraries | 2286 | 1655 | 38 | 152 | 4 | 8 | | Integration tests | 0 | 0 | 0 | 0 | 0 | 0 | | Functional tests | 1687 | 1322 | 31 | 195 | 6 | 4 | | Unit tests | 1356 | 1079 | 27 | 158 | 5 | 4 | +----------------------+-------+-------+---------+---------+-----+-------+ | Total | 9747 | 7613 | 162 | 802 | 4 | 7 | +----------------------+-------+-------+---------+---------+-----+-------+ Code LOC: 5212 Test LOC: 2401 Code to Test Ratio: 1:0.5 Sunday 30 May 2010

RubyParser and Parsetree Ryan Davis and Eric Hodel (‘Ruby Sadists’) Sunday 30 May 2010

RubyParser and Parsetree Abstract syntax tree RubyParser.new.parse(File.read(‘metrics.rb’),‘metric.rb’) class Metrics s(:class,:Metrics, nil, def probe s(:scope, s(:defn,:probe, puts "good" s(:args), end s(:scope, end s(:block, s(:call, nil, :puts, s(:arglist, s(:str, "good")))))))) Symbolic Expression (Sexp) Sunday 30 May 2010

RubyParser and Parsetree Abstract syntax tree RubyParser.new.parse(File.read(‘metrics.rb’),‘metric.rb’) class Metrics s(:class,:Metrics, nil, def probe s(:scope, s(:defn,:probe, puts "good" s(:args), end s(:scope, end s(:block, s(:call, nil, :puts, s(:arglist, s(:str, "good")))))))) Symbolic Expression (Sexp) Ruby2Ruby Sunday 30 May 2010

RubyParser pure ruby Parsetree ruby and inline c < 1.9 Sunday 30 May 2010

rake stats size Flog Flay code complexity code similarities Roodi R_B_P Saikuro Reek cyclomatic antipatterns Rails complexity Heckle Rcov test coverage Sunday 30 May 2010

flog ‘the pain your code is in’ Sunday 30 May 2010

FLOG flog lib/flog.rb 647.8: flog total 13.8: flog/method average 87.5: Flog#output_details 58.8: Flog#process_iter 54.2: Flog#flog 48.8: Flog#parse_options 34.1: Flog#none 23.2: Flog#output_method_details 22.1: Flog#score_method 16.0: Flog#process_block_pass 15.6: Flog#report 15.2: Flog#expand_dirs_to_files 15.0: Flog#klass_name Sunday 30 May 2010

FLOG Assignment Branch Condition (ABC) def score_method(tally) a, b, c = 0, 0, 0 tally.each do |cat, score| case cat when :assignment then a += score when :branch then b += score else c += score end end Math.sqrt(a*a + b*b + c*c) end Sunday 30 May 2010

FLOG Weighing the AST with factors def process_if(exp) add_to_score :branch process exp.shift # cond penalize_by 0.1 do process exp.shift # true process exp.shift # false end s() end Sunday 30 May 2010

FLOG Methods Very good: < 20 All Right: < 50 Sunday 30 May 2010

FLAY code similarities Sunday 30 May 2010

FLAY flay *.rb Total score (lower is better) = 621 1) IDENTICAL code found in :defn (mass*2 = 188) channel.rb:48 clip.rb:80 2) Similar code found in :defn (mass = 93) channel.rb:150 clip.rb:110 clip.rb:116 3) Similar code found in :defs (mass = 58) contact.rb:32 contact.rb:37 Sunday 30 May 2010

FLAY RubyParser def mass @mass ||= self.structure.flatten.size end Hash of structure of nodes with mass > threshold self.hashes[node.structural_hash] << node analyze: if same hash = similar if same node = identical Sunday 30 May 2010

Saikuro cyclomatic complexity Sunday 30 May 2010

Saikuro Sunday 30 May 2010

Saikuro ruby-lex every keyword is interpreted into ‘state’ state used to calculate if, unless, while, until, for, elsif, when, rescue (blocks) Recursively Sunday 30 May 2010

Saikuro Good: methods < 5 Sunday 30 May 2010

Roodi ‘Ruby Object Oriented Design Inferometer’ nutmeg66 on ﬂickr Sunday 30 May 2010

Roodi app/controllers/itineraries_controller.rb:4 - Method name "show" cyclomatic complexity is 14. It should be 8 or less. app/models/itinerary.rb:41 - Block cyclomatic complexity is 6. It should be 4 or less. app/controllers/itineraries_controller.rb:4 - Method "show" has 30 lines. It should have 20 or less. app/helpers/application_helper.rb:27 - Method "clippy" has 26 lines. It should have 20 or less. Sunday 30 May 2010

Roodi RubyParser visitor pattern visitor: checker (Configuration) visitable: parsed nodes = extensible Sunday 30 May 2010

Reek Sunday 30 May 2010

Reek more OO-specific checks Control Couple Data Clump Feature Envy Large Class Long Method Long Parameter List Simulated Polymorphism Uncommunicative Name Sunday 30 May 2010

Reek UserSessionsController has no descriptive comment (Irresponsible Module) UserSessionsController#destroy calls current_user_session twice (Duplication) app/controllers/users_controller.rb -- 5 warnings: UsersController has no descriptive comment (Irresponsible Module) UsersController tests @aid_app at least 4 times (Simulated Polymorphism) UsersController#create calls params 3 times (Duplication) UsersController#create calls params[:user] 3 times (Duplication) ... Sunday 30 May 2010

Reek RubyParser extends parsed nodes traverses nodes returns code after Ruby2Ruby Sunday 30 May 2010

rails_best_practices kamoda on Flickr Sunday 30 May 2010

rails_best_practices ./app/controllers/ws/vmg/aid_user_accounts_controller.rb:160 - move model logic into model (@aid_user_account called_count > 4) ./app/controllers/ws/vmg/ipt_controller.rb:102 - move model logic into model (xml called_count > 4) ./app/controllers/ws/vmg/ipt_controller.rb:102 - move model logic into model (pf called_count > 4) ./config/routes.rb:3 - overuse route customizations (customize_count > 3) ./config/routes.rb:35 - overuse route customizations (customize_count > 3) ./app/models/vmg/scenario.rb:41 - keep finders on their own model Sunday 30 May 2010

rails_best_practices Visitor pattern visitor : checking_visitor visitable: visitable sexp Sunday 30 May 2010

Churn Sunday 30 May 2010

Churn +-------------------------------------------------+---------------+ | file_path | times_changed | +-------------------------------------------------+---------------+ | db/schema.rb | 26 | | config/routes.rb | 24 | | app/controllers/application_controller.rb | 22 | | app/controllers/add_apps_controller.rb | 22 | | config/environment.rb | 20 | | app/views/layouts/application.html.erb | 20 | | app/models/ability.rb | 18 | ... Sunday 30 May 2010

Churn Not only classes but also methods (RubyParser) Version control: git, Hg, svn Locates changes in source using logs (as in git log) Sunday 30 May 2010

Churn common sense ... mostly useful in maintenance phase Sunday 30 May 2010

Rcov Sunday 30 May 2010

Rcov Total coverage: comments included Sunday 30 May 2010

Rcov Executes test keeps track of the executed lines Using C extension when possible to hook into MRI (experimental for 1.9) Sunday 30 May 2010

Rcov good: 100% coverage Sunday 30 May 2010

Heckle Sunday 30 May 2010

Heckle ParseTree + Ruby2Ruby mutate time-consuming: combinatorials more for small programs (gems, scripts) doesn’t work for ruby 1.9 (ParseTree) Sunday 30 May 2010

Heckle Initial tests pass. Let's rumble. ********************************************************************** *** AidApp#property_names loaded with 4 possible mutations ********************************************************************** 4 mutations remaining... Replacing AidApp#property_names with: --- original +++ mutation def property_names - (meta_policy and meta_policy.property_names_for(:aid_app)) + (nil and meta_policy.property_names_for(:aid_app)) end Sunday 30 May 2010

rake stats size Flog Flay code complexity code similarities Roodi Saikuro Reek cyclomatic antipatterns RAILS_BEST complexity _PRACTICES Heckle Rcov test coverage Sunday 30 May 2010

metric_fu Sunday 30 May 2010

check out the good stuff OrbitalJoe on ﬂickr Sunday 30 May 2010

what these metrics don’t tell you Bugs Sunday 30 May 2010

what these metrics don’t tell you code performance Ruby Profiling Sunday 30 May 2010

Reads like a book Sunday 30 May 2010

http://railroad.rubyforge.org/ http://www.igvita.com/2008/12/11/ruby-ast-for-fun-and-proﬁt/ http://ruby.sadi.st/Ruby_Sadist.html http://goruco2008.confreaks.com/04_davis.html http://cwd.dhemery.com/2009/11/wmaat/ http://c2.com/cgi/wiki?AbcMetric http://hissa.nist.gov/HHRFdata/Artifacts/ITLdoc/235/title.htm http://blog.rubybestpractices.com/posts/judofyr/sexp-for- rubyists.html Elise Huard @elise_huard elise@elisehuard.be http://jabberwocky.eu http://github.com/elisehuard Sunday 30 May 2010

how to rate a Rails application

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