TDD using Minitest

Talk gave in the 1º Tech Day, GURU-PR 2015 @ EBANX Headquarters

Transcript

1. TDD using Minitest 1º Tech Day, GURU-PR 2015
2. Agenda • Test-Driven Development ◦ Overview ◦ Why to use • Minitest ◦ Overview ◦ How to use
3. Test-Driven Development
4. "... a software development process that relies on the repetition of a very short development cycle: first the developer writes an (initially failing) automated test case that defines a desired improvement, then produces the minimum amount of code to pass that test, and finally refactors the new code to acceptable standards." Wikipedia
5. Process vs. Quality
6. Smart developers can make Progress without Process ...but it's not good!
7. …
8. Process is the difference between... Surgery and Cutting people open
9. Process is the difference between... Software Engineering and Programming
10. Professionals: Design, Plan and Prepare first
11. Process - The TDD Cycle
13. Benefits of the Test First approach
14. Requirements. Think about it first...
15. Better Code Design
16. Better Code Design • Focus on How to use, its Interface/API "the expected behavior" rather than "how this is implemented"
17. Better Code Design It's all about feedback!
18. Better Code Design
19. Simple vs Complex
20. Better Code Design • Feedback from Test Smells ◦ Over-mocking ◦ Hard to write tests ◦ Too much responsibility ◦ Too many assertions
21. Code Design Feedback - Example describe User do subject { User.new } describe "its registration process" do let(:address) { AnObject.new } let(:phone) { Another.new } let(:children) { OtherOne.new } let(:mailer) { AnyObject.new } # etc... it "saves the related address" do # Test saving of the address end it "saves the related children" do # Test saving of children end it "saves the related phones" ... it "saves the user" ... it "sends and email to the user" ... end end
22. Live Documentation
23. Any broken code?
24. Minitest - Overview
25. What's Minitest? • Replacement for Ruby 1.8's test/unit ◦ Originally 90 lines of code • Available built-in with Ruby 1.9 • Available as a gem • Meant to be small, clean, and very fast
26. What's Minitest? 6 parts • runner: The heart of the machine • minitest/unit: TDD API • minitest/spec: BDD API • minitest/mock: Simple mocking API • minitest/pride: IO pipelining example • minitest/bench: Abstract benchmark API
27. Minitest Philosophy • Less is more ◦ Very small in comparison with RSpec ◦ Very Fast • Isolated Tests ◦ Test Randomization: Prevents order dependencies • Indirection is the Enemy ◦ Failures pointing to the failure
28. Minitest vs. RSpec Lines of Code (2015) • Minitest: 1,589 • RSpec: 15,095
29. Minitest vs. RSpec
30. It's just Ruby! Magic free!
31. Test Cases are Classes
32. Tests are Methods
33. minitest/unit require 'minitest/autorun' class CatTest < Minitest::Unit::TestCase def test_meow assert_equal "Meoooow!", Cat.say_meow end end
34. minitest positive assertions assert assert_block * assert_empty assert_equal assert_in_delta assert_in_epsilon assert_includes assert_instance_of assert_kind_of assert_match assert_nil assert_operator assert_output * assert_predicate assert_raises * assert_respond_to assert_same assert_send * assert_silent * assert_throws *
35. minitest negative assertions refute refute_empty refute_equal refute_in_delta refute_in_epsilon refute_includes refute_instance_of refute_kind_of refute_match refute_nil refute_operator refute_predicate refute_respond_to refute_same
36. minitest/spec require 'minitest/autorun' describe Cat do it "says meow" do Cat.say_meow.must_equal "Meoooow!" end end
37. minitest expectations must_be must_be_close_to must_be_empty must_be_instance_of must_be_kind_of must_be_nil must_be_same_as must_be_silent * must_be_within_delta must_be_within_epsilon must_equal must_include must_match must_output * must_raise * must_respond_to must_send * must_throw *
38. minitest negative expectations wont_be wont_be_close_to wont_be_empty wont_be_instance_of wont_be_kind_of wont_be_nil wont_be_same_as wont_be_within_delta wont_be_within_epsilon wont_equal wont_include wont_match wont_respond_to
39. Minitest Ecosystem minitest-chef-handler minitest-reporters minitest-rails guard-minitest minitest-spec-rails minitest-capybara spork-minitest minitest-metadata minitest-rails-capybara minitest-matchers capybara_minitest_spec minitest-colorize minitest-rg minitest-ci (many more…)
40. TDD + Minitest
41. Red - Write the test require 'minitest/autorun' describe Article do subject { Article.new } it "can be posted on Twitter" do subject.post_on_twitter subject.twitted?.must_equal true end end
42. Red - See it failing $ruby -Ilib spec/article_spec.rb spec/article_spec.rb:3:in `<main>': uninitialized constant Article (NameError)
43. Green - Implements the code class Article end
44. Red - See it failing $ ruby -Ilib spec/article_spec.rb Run options: --seed 34214 1) Error: Article#test_0001_can be posted on Twitter: NoMethodError: undefined method `post_on_twitter' for #<Article:0x000000012c75d0> spec/article_spec.rb:8:in `block (2 levels) in <main>' 1 runs, 0 assertions, 0 failures, 1 errors, 0 skips
45. Green - Implements the code class Article def post_on_twitter end end
46. Red - See it failing $ ruby -Ilib spec/article_spec.rb Run options: --seed 47611 1) Error: Article#test_0001_can be posted on Twitter: NoMethodError: undefined method `twitted?' for #<Article: 0x00000002347130> spec/article_spec.rb:9:in `block (2 levels) in <main>' 1 runs, 0 assertions, 0 failures, 1 errors, 0 skips
47. Green - Implements the code class Article # ... def twitted? end end
48. Red - See it failing $ ruby -Ilib spec/article_spec.rb Run options: --seed 19132 # Running: F... 1) Failure: Article#test_0001_can be posted on Twitter [spec/article_spec. rb:9]: Expected: true Actual: nil
49. Green - Implements the code class Article def post_on_twitter # Logic to post the article (...) @twitted = true end end
50. Green - Implements the code class Article # ... def twitted? @twitted end end
51. Green - See it passing % ruby -Ilib spec/article_spec.rb Run options: --seed 37685 # Running: ......................................................... ............. (etc) Finished in 0.107130s, 1446.8403 runs/s, 2959.0217 assertions/s. 155 runs, 317 assertions, 0 failures, 0 errors, 0 skips
52. Green - See it passing % ruby -Ilib spec/article_spec.rb Run options: --seed 37685 # Running: ......................................................... ............. (etc) Finished in 0.107130s, 1446.8403 runs/s, 2959.0217 assertions/s. 155 runs, 317 assertions, 0 failures, 0 errors, 0 skips
53. Refactor - Improving the code
54. Q&A?
55. Thanks! github.com/diogenes