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Speedy TDD with RailsReclaiming your feedback loop (the wrong way) Creative Commons Attribution-Noncommercial-Share Alike Ash Moran 2.0 UK: England & Wales License PatchSpace Ltd

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ierSpeedy TDD with RailsReclaiming your feedback loop (the wrong way) Creative Commons Attribution-Noncommercial-Share Alike Ash Moran 2.0 UK: England & Wales License PatchSpace Ltd

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What say Google about tests?

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JavaScriptNothing unusual here

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ClojureSeems pretty uneventful too

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ScalaEqually unexciting

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PythonTesting is pretty boring really

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JavaYou’re probably ok as long as you speak German

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C#More concerned with recruitment than code

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FortranYou’re on your own

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DjangoSince, in fairness, we’re testing web apps here

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RailsYou can hear their pained cries for help

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Why does test speed matter?

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Red Refactor GreenThe TDD loopThis constrains how fast you can learn whetheryour code implements the specification

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TDD orders of magnitude0.01s Full-app validation on every run0.1s Continuous development flow1s Interrupted development flow10s Check Twitter more than you check your app

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What is the current situation?

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Rails: one testOne RSpec exampleRSpec 2.8.0 on MRI Ruby 1.9.3

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Rails: 16 testsBooting Rails is the constraint

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What can we do?

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Attack vector 1:The Ruby Runtime

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Upgrade from Ruby 1.9.2The `require` method is much faster in 1.9.3But… Heroku currently only offers 1.9.2

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Switch to 1.8.7 This was seriously proposed to me on the rspec-users list Baby + bathwater?

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Attack vector 2:Pre-loading and forking Rails

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Spinhttps://github.com/jstorimer/spinStart the server (loads Rails): spin serveRun tests spin push test/unit/product_test.rb spin push a_test.rb b_test.rb …No changes to the app whatsoeverInternally does some jiggery-pokery for RSpec

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Guard::Spinguard spin do watch(%r{^spec/.+_spec.rb}) watch(%r{^app/(.+).rb}) { |m| "spec/#{m[1]}_spec.rb" } watch(%r{^app/(.+).haml}) { |m| "spec/#{m[1]}.haml_spec.rb" } watch(%r{^lib/(.+).rb}) { |m| "spec/lib/#{m[1]}_spec.rb" } watch(%r{^app/controllers/(.+)_(controller).rb}) { |m| [ "spec/routing/#{m[1]}_routing_spec.rb", "spec/#{m[2]}s/#{m[1]}_#{m[2]}_spec.rb", "spec/requests/#{m[1]}_spec.rb" ] }end

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Guard::SpinFaster, but not an order of magnitude fasterOutcome: only worth it if it causes no problems

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Sporkhttps://github.com/sporkrb/sporkRequires changing spec_helper.rbUses enough metaprogramming monkey-patching ofRails to summon a Greater Uncle Bob Daemon https://github.com/sporkrb/spork/blob/master/lib/ spork/app_framework/rails.rb#L43-80

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Spork monkey-patchingdef preload_rails if deprecated_version && (not /^3/.match(deprecated_version)) puts "This version of spork only supports Rails 3.0. To use spork with rails 2.3.x, downgrade to spork 0.8.x." exit 1 end require application_file ::Rails.application ::Rails::Engine.class_eval do def eager_load! # turn off eager_loading, all together end end # Spork.trap_method(::AbstractController::Helpers::ClassMethods, :helper) Spork.trap_method(::ActiveModel::Observing::ClassMethods, :instantiate_observers) Spork.each_run { ActiveRecord::Base.establish_connection rescue nil } if Object.const_defined?(:ActiveRecord) …

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Spork monkey-patching…AbstractController::Helpers::ClassMethods.module_eval do def helper(*args, &block) ([args].flatten - [:all]).each do |arg| next unless arg.is_a?(String) filename = arg + "_helper" unless ::ActiveSupport::Dependencies.search_for_file(filename) # this error message must raise in the format such that LoadError#path returns the filename raise LoadError.new("Missing helper file helpers/%s.rb" % filename) end end Spork.each_run(false) do modules_for_helpers(args).each do |mod| add_template_helper(mod) end _helpers.module_eval(&block) if block_given? end endend

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Forking Rails? Only saves part of the time Introduces potential problems Reloading the pre-fork Hacks to make it work Can introduce many subtle bugs Doesn’t address the real problem: depending on Rails

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Attack vector 3:Hijack code reloading forbrowser integration tests

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Code reloadingUsed in the development environmentCalled cache_classes This is a lie! Ruby does not have real code reloading like ErlangCan be used to speed up browser integration tests Called “acceptance” here, which may not be true

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Guard::Rails# Running with `daemon: true` because I cant figure out how to turn off enough Rails loggingguard "rails", environment: "acceptance", server: :thin, port: 3100, daemon: true do watch("Gemfile.lock") watch(%r{^(config|lib)/.*})endguard "rspec", spec_paths: %w[ spec/acceptance ], cli: "--color --format Fuubar" do watch(%r{^spec/acceptance/.+_spec.rb$})end

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environments/acceptance.rb MyApp::Application.configure do config.cache_classes = false config.consider_all_requests_local = true config.active_support.deprecation = :log config.assets.compress = false config.action_mailer.default_url_options = { :host => localhost:3000 } config.action_mailer.delivery_method = :smtp config.action_mailer.smtp_settings = { :address => "localhost", :port => 1025, :enable_starttls_auto => false } # Disable logging for now (too much noise in Guard) # I couldnt figure out how to make it log so running this as a daemon instead # config.logger = nil # config.action_controller.logger = nil # config.action_view.logger = nil end Mongoid.configure do |config| config.logger = nil end

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capybara-webkit testsFeedback time comparable to controller tests

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Code reloading summarySpeeds up start time of browser tests considerablyTests must be written to work cross-processFewer issues than Spin/Spork (lesser of two evils)No help at all speeding up controller testsStill doesn’t address the real problem

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Attack vector 4:Split the tests by dependency

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Example: Mongoid require spec_helper require spec/environments/mongoid require_unless_rails_loaded app/models/question require_unless_rails_loaded app/models/user require spec/support/blueprints/question describe Question do describe "#populate" do let(:source_question) { Question.make(value: "Submetric 1a Q1", comment: "Submetric 1a A1") } let(:target_question) { Question.make(value: "this does not get overwritten", comment: "this gets overwritten") } before(:each) do source_question.populate(target_question) end subject { target_question } its(:value) { should be == "this does not get overwritten" } its(:comment) { should be == "Submetric 1a A1" } end end

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spec/environments/mongoid require_relative common # Gem dependencies require mongoid if !rails_loaded? ENV["RACK_ENV"] ||= "test" # Hack to use the Mongoid.load! Mongoid.load!("config/mongoid.yml") Mongoid.configure do |config| config.logger = nil end end RSpec.configure do |config| config.before(:each) do Mongoid::IdentityMap.clear end end

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spec/environments/common def require_unless_rails_loaded(file) require(file) unless rails_loaded? end This may be paranoia

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spec_helper.rb def rails_loaded? Object.const_defined?(:MyApp) && MyApp.const_defined?(:Application) end

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Guardfile (multiple guards) guard "rspec", spec_paths: %w[ spec/controllers ], cli: "--color --format Fuubar" do watch(spec/environments/rails.rb) { "spec/controllers" } watch(%r{^spec/controllers/.+_spec.rb$}) watch(%r{^app/controllers/(.+).rb$}) { |m| "spec/#{m[1]}_spec.rb" } end guard "rspec", spec_paths: %w[ spec/models ], cli: "--color --format Fuubar" do watch(spec/spec_helper.rb) { "spec/models" } watch(spec/environments/mongoid.rb) { "spec/models" } watch(%r{^spec/support/(.+).rb$}) { "spec/models" } watch(%r{^spec/models/.+_spec.rb$}) watch(%r{^app/models/(.+).rb$}) { |m| "spec/#{m[1]}_spec.rb" } watch(%r{^app/models/concerns.rb$}) { |m| "spec/models" } end

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Running in GuardMongoid tests now running ~1s not ~10sNot brilliant, but an order of magnitude change

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Concluding thoughts

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How much does this help?Bypassing the Rails boot process can increasefeedback speed by an order of magnitudeWithout changing your code, you can turn a nightmareinto a bad dreamThe size of the gains depend on how manydependencies you have left

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Is this the right way? No. Tune in next month for “Speedy TDD in Rails (the righter way”!