Creando Test Suites Mantenibles

Transcript

1. Creando Test Suites Mantenibles RubyConf Uruguay - 12 de Noviembre, 2011. Harold Giménez - @hgimenez
2. ¿Quién soy? Desarrollador en thoughtbot Consulting, Training, Productos Enfoque en Ruby, Rails, Javascript. Proceso, ágil y desarrollo de software de alta calidad, rápido. Comunidad y Open Source
3. ¿Qué es un Test Suite mantenible? Detector de bugs, previene regresiones Facilita el Refactoring Elimina todo tipo de comportamiento aleatorio Independencia entre tests Ejecutable sin conección de red
4. El Plan
5. No utilices generadores de data aleatoria
6. random-data, Faker, forgery user = User.create(password: Forger(:basic).password, email: Forgery(:basic).email) user.purchase!(item) user.should have_purchased(item) Finished in 0.0418 seconds 1 example, 0 failures
7. Pasa un tiempo y necesitas mas restricciones con los passwords class User validates :password, length: { min: 8 } end
8. user.purchase!(item) user.should have_purchased(item) Finished in 0.0223 seconds 1 example, 0 failures
9. user.purchase!(item) user.should have_purchased(item) Finished in 0.0223 seconds 1 example, 1 failure user.name # => José user.name.length # => 4
10. FAIL
11. Usa factories
12. Usa factories Fixtures compartidos inmantenibles y lentos Manten los setups a lo mínimo, y cerca del test Que revelen la intención del test
13. FactoryGirl
14. Usa factories subject do User.create(email: 'user@example.com', password: 'password', password_confirmation: 'password', date_of_birth: '01-13-1983') end its(:age) { should == 27 }
15. Usa factories subject do User.create(email: 'user@example.com', password: 'password', password_confirmation: 'password', date_of_birth: '01-13-1983') end its(:age) { should == 27 }
16. Usa factories spec/factories.rb FactoryGirl.define do factory :user do email password 'password' end end spec/models/user_spec.rb subject { create(:user, date_of_birth: '02-03-1983') } its(:age) { should == 27 }
17. Fresh Fixtures let(:data) { File.read('fixtures/data.xml) } subject { build(:scores, data: data) } it 'builds a parsed XML document from the data' do subject.document.at('.//event/description').text.should == 'Boston vs. Montreal' end
18. Fresh Fixtures let(:data) { File.read('fixtures/data.xml) } subject { build(:scores, data: data) } it 'builds a parsed XML document from the data' do subject.document.at('.//event/description').text.should == 'Boston vs. Montreal' end
19. Fresh Fixtures let(:data) { build_xml(home_team: 'Boston', away_team: 'Montreal' } subject { build(:scores, data: data) } it 'builds a parsed XML document from the data' do subject.document.at('.//event/description').text.should == 'Boston vs. Montreal' end def build_xml(opts) builder = Builder::XmlMarkup.new builder.event do |event| event.description "#{opts[:home_team]} vs. # {opts[:away_team]}" # ... end end
20. No sobre-especificar
21. No sobre-especificar No digas cómo, sino qué No crear stubs en el SUT Complica hacer refactoring Señal de violaciones del Single Responsability Principle, Law of Demeter Traza la linea
22. No digas cómo, sino qué class User def card_number fetch_credit_card.number end def fetch_credit_card card = Net::HTTP.new('https://gateway.com').get("/cards/# {self.remote_id}") CreditCard.new(card['data']) end end
23. No digas cómo, sino qué describe User, '#card_number' do subject { create(:user) } it "returns the user's credit card" do mock_http = stub mock_http.stubs(get: { number: 1234 }) Net::HTTP.stubs(new: mock_http) subject.card_number.should == '1234' end end
24. No digas cómo, sino qué describe User, '#card_number' do subject { create(:user) } it "returns the user's credit card" do mock_http = stub mock_http.stubs(get: { number: 1234 }) Net::HTTP.stubs(new: mock_http) subject.card_number.should == '1234' end end
25. Stubs en el SUT describe User, '#card_number' do subject { create(:user) } it "returns the user's credit card" do card = CreditCard.new(number: '1234') subject.stubs(fetch_credit_card: card) subject.card_number.should be == '1234' end end
26. Stubs en el SUT describe User, '#card_number' do subject { create(:user) } it "returns the user's credit card" do card = CreditCard.new(number: '1234') subject.stubs(fetch_credit_card: card) subject.card_number.should be == '1234' end end
27. Stubs en el SUT describe User, '#card_number' do subject { create(:user) } it "returns the user's credit card" do fake_card = stub(number: '1234') CreditCard.stubs(new: fake_card) subject.card_number.should be == '1234' end end
28. Usa Inyección de Dependencias class User def card_number fetch_credit_card.number end def fetch_credit_card CreditCard.new(user: self).fetch end end
29. Usa Inyección de Dependencias class User def card_number fetch_credit_card.number end def fetch_credit_card credit_card_fetcher.new(user: self).find end def credit_card_fetcher @fetcher ||= CreditCard end def credit_card_fetcher=(fetcher_class) @fetcher = fetcher_class end end
30. Usa Inyección de Dependencias describe User, '#card_number' do class FakeCreditCard def initialize(user); end def fetch CreditCard.new(number: '1234') end end subject { create(:user) } before { subject.credit_card_fetcher = FakeCreditCard } it "returns the user's card number" do subject.card_number.should be == '1234' end end
31. Usa Inyección de Dependencias describe User, '#card_number' do class FakeCreditCard def initialize(user); end def fetch CreditCard.new(number: '1234') end end subject { create(:user) } before { subject.credit_card_fetcher = FakeCreditCard } it "returns the user's card number" do subject.card_number.should be == '1234' end end
32. No dependas del tiempo
33. No dependas del tiempo Muy fácil crear tests que pasan en la mañana y no en la tarde Muy fácil crear tests que pasan ahora, pero no cuando cambia el DST. Muy fácil crear tests que pasan en tu computador, pero no en CI. Tiempo del servidor distinto al cliente: tests para Javascript se complican
34. No dependas del tiempo let(:article) { build(:article) } before { article.publish! } it 'displays the published date and time' do assigns[:article] = article render response.should contain("Published at #{Time.now.to_s}") end . Finished in 0.1428 seconds 1 example, 0 failures
35. No dependas del tiempo let(:article) { build(:article) } before { article.publish! } it 'displays the published date and time' do assigns[:article] = article render response.should contain("Published at #{Time.now.to_s}") end F Finished in 0.1234 seconds 1 example, 1 failure
36. No dependas del tiempo Solución 1: Timecop let(:article) { build(:article) } before do Timecop.freeze article.publish! end after { Timecop.return } it 'displays the published date and time' do assigns[:article] = article render response.should contain("Published at #{Time.now.to_s}") end . Finished in 0.0981 seconds 1 example, 0 failures
37. No dependas del tiempo Solución 2: parametizar tiempo de publicación class Article def publish(time = Time.now) update_attributes(published: true, published_at: time) end end let(:article) { build(:article) } let(:publish_time) { Time.now } before { article.publish!(publish_time) } it 'displays the published date and time' do assigns[:article] = article render response.should contain("Published at #{publish_time.to_s}") end . Finished in 0.0981 seconds 1 example, 0 failures
38. No dependas del tiempo Javascript: forzar la hora del servidor en el cliente Ejemplo en Rails: <%= javascript_tag do -%> Date.currentDate = function() { <% if Rails.env.test? -%> return new Date(<%== Time.now.to_json %>); <% else -%> return new Date(); <% end -%> }; <% end -%> Luego ser juiciozo con siempre utilizar Date.currentDate() en lugar de new Date()
39. No Duermas
40. No Duermas Comportamiento asincrónico como Ajax es complicado de testear Cómo NO testearlo: make_call() sleep(5) check_response() Si el response es en 1 segundo, tu suite pierde 4 segundos esperando Peor aun, si el response es en 6 segundos, tienes un falso negativo.
41. No Duermas Ejemplo con capybara before do create(:album, title: 'Dark side of the moon') create(:album, title: 'Dark Magus') create(:album, title: 'Jimi: Blues') end visit '/search' fill_in 'Search', with: 'Dark' click_button 'Submit' sleep(5) page.should have_content('Dark side of the moon') page.should have_content('Dark Magus') page.should have_no_content('Jimi: Blues')
42. No Duermas before do create(:album, title: 'Dark side of the moon') create(:album, title: 'Dark Magus') create(:album, title: 'Jimi: Blues') end visit '/search' fill_in 'Search', with: 'Dark' click_button 'Submit' sleep(5) page.should have_content('Dark side of the moon') page.should have_content('Dark Magus') page.should have_no_content('Jimi: Blues')
43. No Duermas before do create(:album, title: 'Dark side of the moon') create(:album, title: 'Dark Magus') create(:album, title: 'Jimi: Blues') end visit '/search' fill_in 'Search', with: 'Dark' click_button 'Submit' wait_limit = 5 start_time = Time.now until done do raise TimeoutError if (Time.now - start_time) > wait_limit done = page.has_content?('Here are your results') sleep(0.1) end page.should have_content('Dark side of the moon')
44. No Duermas before do create(:album, title: 'Dark side of the moon') create(:album, title: 'Dark Magus') create(:album, title: 'Jimi: Blues') end visit '/search' fill_in 'Search', with: 'Dark' click_button 'Submit' Capybara.wait_until(5) do page.should have_content('Dark side of the moon') page.should have_content('Dark Magus') page.should have_no_content('Jimi: Blues') end
45. Fakes para servicios remotos
46. Usa fakes para testear servicios remotos Elimina necesidad por connecciones de red Tests mas rapidos Puedes imponer el estado del servicio para testear edge cases Puedes testear comportamiento de tu sistema cuando hay timeouts en el servicio remoto Elimina fallas de tus tests causados por problemas en el servicio
47. Ejemplo: FakeKissmetrics para sham_rack class FakeKissmetrics cattr_accessor :requests def self.clear_requests @@events = [] end def call(env) request = Rack::Request.new(env) @@events << request.params [200, { 'Content-Length' => 0 }, []] end def self.has_recorded_event?(event_name) @@events.map { |r| r['_n'] }.include? event_name end end
48. Ejemplo: FakeKissmetrics para sham_rack class FakeKissmetrics cattr_accessor :requests def self.clear_requests @@events = [] end def call(env) request = Rack::Request.new(env) @@events << request.params [200, { 'Content-Length' => 0 }, []] end def self.has_recorded_event?(event_name) @@events.map { |r| r['_n'] }.include? event_name end end
49. Ejemplo: FakeKissmetrics para sham_rack class FakeKissmetrics cattr_accessor :requests def self.clear_requests @@events = [] end def call(env) request = Rack::Request.new(env) @@events << request.params [200, { 'Content-Length' => 0 }, []] end def self.has_recorded_event?(event_name) @@events.map { |r| r['_n'] }.include? event_name end end
50. Ejemplo: FakeKissmetrics para sham_rack require 'sham_rack' Before do ShamRack.mount(FakeKissmetrics.new, 'trk.kissmetrics.com') end After do FakeKissmetrics.clear_requests end
51. Usa fakes para testear servicios remotos visit '/sign_in' fill_in 'email', with: 'user@example.com' fill_in 'password, with: 'password' click_button 'Submit' FakeKissmetrics.should have_recorded_event('Signed up')
52. Fake Heroku en suspenders Scenario: User uses the --heroku=true command line argument When I suspend a project called "test_project" with: | argument | value | | --heroku | true | Then the "test_project-production" heroku app should exist And the "test_project-production" heroku app should exist
53. Fake Heroku en suspenders Scenario: User uses the --heroku=true command line argument When I suspend a project called "test_project" with: | argument | value | | --heroku | true | Then the "test_project-production" heroku app should exist And the "test_project-production" heroku app should exist
54. Then /^the "([^"]*)" heroku app should exist$/ do |app_name| FakeHeroku.should have_created_app(app_name) end
55. class FakeHeroku def initialize(args) @args = args end def run! File.open(RECORDER, 'a') do |file| file.write @args.join(' ') end end def self.clear! FileUtils.rm_rf(RECORDER) end def self.has_created_app?(app_name) File.open(RECORDER, 'r').read.include?("create #{app_name}") end end After do FakeHeroku.clear! end
56. class FakeHeroku def initialize(args) @args = args end def run! File.open(RECORDER, 'a') do |file| file.write @args.join(' ') end end def self.clear! FileUtils.rm_rf(RECORDER) end def self.has_created_app?(app_name) File.open(RECORDER, 'r').read.include?("create #{app_name}") end end After do FakeHeroku.clear! end
57. class FakeHeroku def initialize(args) @args = args end def run! File.open(RECORDER, 'a') do |file| file.write @args.join(' ') end end def self.clear! FileUtils.rm_rf(RECORDER) end def self.has_created_app?(app_name) File.open(RECORDER, 'r').read.include?("create #{app_name}") end end After do FakeHeroku.clear! end
58. class FakeHeroku def initialize(args) @args = args end def run! File.open(RECORDER, 'a') do |file| file.write @args.join(' ') end end def self.clear! FileUtils.rm_rf(RECORDER) end def self.has_created_app?(app_name) File.open(RECORDER, 'r').read.include?("create #{app_name}") end # recuerda: # FakeHeroku.should have_created_app(app_name) end
59. Cuarentena
60. Cuarentena para tests con resultados impredecibles Tests que tienen failures esporádicos No permitir que hayan mas de 7 Un dia a la semana/mes/lo que sea dedicado a limpiar la cuarentena
61. Con cucumber features/something_failing.feature @quarantine Scenario: Something that is failing right now When I go to the home page And I vote for Pedro Then ... config/cucumber.yml default: --tags ~@quarantine quarantine: --tags @quarantine
62. Con Rspec describe 'something that is failing right now', quarantine: true do it 'does stuff' do (2 + 2).should == 5 end end spec/spec_helper.rb Rspec.configure do |config| config.filter_run_excluding quarantine: true end > rspec --tags ~quarantine > rspec --tags quarantine
63. Refactoring de los tests
64. xunitpatterns.com
65. Working Effectively with Legacy Code
66. robots.thoughtbot.com/tagged/testing
67. Practiquen BDD! github.com/hgimenez/stack github.com/hgimenez/undo_redo_stack github.com/hgimenez/string_set github.com/coreyhaines/practice_game_of_life
68. ¡Gracias! RubyConf Uruguay - 12 de Noviembre, 2011. Harold Giménez - @hgimenez