Speedy TDD with Rails

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

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

What say Google about tests?

JavaScriptNothing unusual here

ClojureSeems pretty uneventful too

ScalaEqually unexciting

PythonTesting is pretty boring really

JavaYou’re probably ok as long as you speak German

C#More concerned with recruitment than code

FortranYou’re on your own

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

RailsYou can hear their pained cries for help

Why does test speed matter?

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

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

What is the current situation?

Rails: one testOne RSpec exampleRSpec 2.8.0 on MRI Ruby 1.9.3

Rails: 16 testsBooting Rails is the constraint

What can we do?

Attack vector 1:The Ruby Runtime

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

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

Attack vector 2:Pre-loading and forking Rails

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

Guard::Spinguard spin do watch(%r{^spec/.+_spec.rb}) watch(%r{âpp/(.+).rb}) { |m| "spec/#{m[1]}_spec.rb" } watch(%r{âpp/(.+).haml}) { |m| "spec/#{m[1]}.haml_spec.rb" } watch(%r{^lib/(.+).rb}) { |m| "spec/lib/#{m[1]}_spec.rb" } watch(%r{âpp/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

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

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

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) …

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

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

Attack vector 3:Hijack code reloading forbrowser integration tests

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

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

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

capybara-webkit testsFeedback time comparable to controller tests

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

Attack vector 4:Split the tests by dependency

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

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

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

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

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$}) watch(%r{âpp/controllers/(.+).rb$}) { |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{âpp/models/(.+).rb$}) { |m| "spec/#{m[1]}_spec.rb" } watch(%r{âpp/models/concerns.rb$}) { |m| "spec/models" } end

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

Concluding thoughts

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

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

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Speedy TDD with Rails

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