Rails Testing AntiPatterns

Back in 1999, Kent Beck popularized test-first development with his industry changing book eXtreme Programming Explained. Since that time, testing in our applications is not something that would be nice to have, but essential to inspire confidence, catch regressions, and encourage simple designs. However, since tests have become such a large percentage of our applications, they also are prone to code smells and various testing anti patterns.

In his talk, Kevin Faustino will go through various Testing AntiPatterns he has found in Rails projects.

Transcript

1. Rails Testing Anti-Patterns
2. I’m Kevin or @kfaustino
3. I work here
4. “A pattern that shouldn’t be used because it is known to produce less than optimal results.” -Gerard Meszaros
5. Developers Not Writing Tests
6. Don’t Mortgage Your Future
7. Excuses
10. Why Test?
11. Feedback
12. Quality
13. Better Designed Code
14. Confidence
15. Mystery Guest
16. Test Reader is not able to see the cause and effect between the fixture and the verification logic
17. Rails Fixtures describe Order do it 'sets purchase price' do order = Order.last # Where did we even set this ? order.purchase_price.should eq("9.99") # ???? end end
18. Don’t Use “Fixtures”
19. Global
20. Spread Out
21. Distant
22. Brittle
23. Solution: Use Factories!
24. Local describe User do let(:first_name) { 'Bruce' } let(:last_name) { 'Wayne' } subject { FactoryGirl.build(:user, first_name: first_name, last_name: last_name) } its(:full_name) { should eq("#{first_name} + #{last_name}") } end
25. Create only the smallest amount of data needed to expose the issue in each test
26. Bad Factories
27. Empty Factory FactoryGirl.define do factory :user do end end
28. Valid Factory FactoryGirl.define do factory :user do email first_name { Faker::Name.first_name } last_name { Faker::Name.last_name } password "password1" end end
29. Test Your Factories! FactoryGirl.factories.map(&:name).each do |factory_name| describe "The #{factory_name} factory" do it 'is valid' do build(factory_name).should be_valid end end end -http://robots.thoughtbot.com/post/30994874643/testing-your-factories-first
30. Only have the fields necessary to create a valid object
31. Use a sequence when uniqueness is required
32. FactoryGirl.define do factory :category do sequence(:name) {|n| "Name-#{n}" } end end
33. Set belong_to relationships FactoryGirl.define do factory :standing do season # Season Factory team # Team Factory season_type 'regular' end end
34. Erratic Test
35. Don’t depend on external resources!
36. WebMock (HTTP) stub_request(:get, "www.example.com").with(body: 'abc')
37. FakeRedis (redis) require "fakeredis" redis = Redis.new >> redis.set "foo", "bar" => "OK" >> redis.get "foo" => "bar"
38. timecop (Time) new_time = Time. local(2008, 9, 1, 12, 0, 0) Timecop.freeze(new_time) sleep(10) new_time == Time.now # ==> true
39. Frequent Debugging
40. Can be a sign of lack of test coverage
41. Lack of Defect Localization
42. Solution: Verify a single condition per test
43. describe "#to_rss" do let(:url) { 'http://adventuresincoding.com' } subject { Nokogiri::XML(blog.to_rss) } def text_at(*args) args.inject(subject) { |s,r| s.send(:at, r) }.inner_text end it "must be RSS version 2.0" do subject.at('rss')['version'].should == '2.0' end it "has a title" do text_at('rss', 'title').should eq(subject.title) end it "has a link to the blog" do text_at('rss','link').should eq(url) end end
44. Slow Tests
45. Too much Database interaction!
46. Solution: Use object instances and Test Doubles where you don’t need Database verification
47. Your controller specs don’t need to call the database! Use mocks
48. Bad Cucumber
49. Old Cukes Feature: Signing In Background: Given I am not authenticated Scenario: Successful Login Given 1 user And I go to the sign in page When I fill in "Email" with "bruce@wayneenterprises.com" And I fill in "Password" with "batman" And I press "Sign in" Then I should be on the dashboard page And I should see "Signed in successfully."
50. Avoid Incidental Details Scenario: Successful Login Given a user exists When I sign in Then I should be shown the dashboard
51. Use Declarative Style Scenario: Redirect user to originally requested page after logging in Given I am an unauthenticated User When I attempt to view some restricted content Then I am shown a login form When I authenticate with valid credentials Then I should be shown the restricted content Example Source: The Cucumber Book
52. Create Helpers! module MemberHelpers def member @member ||= Member.last end end World(MemberHelpers)
53. Lack of Controller Tests
54. But I write integration tests so I don’t have to :P
55. Integration Tests covering every single possible controller code path is OVERKILL
56. Results in slow integration tests
57. Write controller tests to have coverage for all your edge cases!
58. A controller is a class with methods It should have tests! http://solnic.eu/2012/02/02/yes-you-should-write-controller-tests.html
59. JavaScript Testing?
60. JavaScript is becoming a very large part of our applications
61. Having 100% code coverage without testing JavaScript is a lie!
63. describe('User', function(){ describe('#save()', function(){ it('should save without error', function(done){ var user = new User('Luna'); user.save(function(err){ if (err) throw err; done(); }); }) }) })
65. Chai has an amazing plugin ecosystem
66. chai-jquery $('.name').should.have.text('John Doe'); $('.name').should.be.visible; $('#exists').should.exist; $('body').should.contain('text'); $('#header').should.have.attr('foo'); etc...
67. Sinon-Chai
68. Why do I care about Sinon?
69. Stub Ajax calls to Rails! var server = sinon.fakeServer.create(); ... server.requests[0].respond( 200, { "Content-Type": "application/json" }, JSON.stringify([{ id: 1, text: "Sinon rules!" }]) );
70. How do I get started?
72. Works with JavaScript & CoffeeScript
73. config/initializers/konacha.rb if defined?(Konacha) require 'capybara/poltergeist' Konacha.configure do |config| config.spec_dir = 'spec/javascripts' config.driver = :poltergeist end end
74. Want to learn more about JavaScript testing in Rails?
75. TorontoRB: November 27th, 2012
76. Remember: Testing == Confidence
77. Questions?