A Guided Read of Minitest

Why is Minitest so much shorter than RSpec? What does Minitest's size tell us about it's philosophy on testing (and Ruby)?

Transcript

1. MINITEST A PHILOSOPHY OF PAIN Exploring testing philosophy through code-reading with @nateberkopec @nateberkopec
2. I'm @nateberkopec. I write about Ruby performance at nateberkopec.com. @nateberkopec
3. Quick Survey @nateberkopec
4. @nateberkopec
5. def object_under_test.stub true end @nateberkopec
6. Pain lead me to learning something new about Ruby. @nateberkopec
7. The elephant in the room: RSpec @nateberkopec
8. @nateberkopec
9. I'm a Minitest guy. @nateberkopec
10. This talk is about the philosophy of Minitest revealed through code. @nateberkopec
11. Minitest is reactionary @nateberkopec
12. History Lesson @nateberkopec
13. 90 lines http://tinyurl.com/ originalminitest @nateberkopec
14. Replacement for test/unit @nateberkopec
15. A code reader's best friend: cloc @nateberkopec
16. Minitest Comments + README: 1699 lines. Ruby code: 1604 lines. @nateberkopec
17. Rspec has 4 major components: → rspec-core → rspec-expectations → rspec-mocks → rspec-support @nateberkopec
18. → rspec-core: 6672 lines → rspec-expectations: 3672 lines → rspec-mocks: 3930 lines → rspec-support: 1569 lines Total: 15843 Lines @nateberkopec
19. Minitest is 1/10th the size of RSpec in total. @nateberkopec
20. If Minitest is The Mouse and The Motorcycle (22,416 words)... @nateberkopec
21. ...RSpec is Ulysses by James Joyce (265,000 words). @nateberkopec
22. Do Less With Less @nateberkopec
23. RSpec includes 1639 lines of formatters! (HTML, JSON, the progress bar, etc) @nateberkopec
24. @nateberkopec
25. rspec-mocks is 28 times larger than minitest/mock @nateberkopec
26. Statism is good. @nateberkopec
27. "A stateist tester asserts that a method returns a particular value. A mockist tester asserts that a method triggers a specific set of interactions with the object's dependencies." - James Golick @nateberkopec
28. @nateberkopec
29. The largest file in RSpec is configuration.rb 758 lines @nateberkopec
30. The largest file in Minitest is minitest.rb 446 lines @nateberkopec
31. Minitest knows whats best for you @nateberkopec
32. @nateberkopec
33. @nateberkopec
34. # test.rb require 'minitest/autorun' class MyTest < Minitest::Test def test_the_truth assert_equal 1, 1 end end @nateberkopec
35. $ ruby test.rb Run options: --seed 20624 # Running: . Finished in 0.001794s, 557.4841 runs/s, 557.4841 assertions/s. 1 runs, 1 assertions, 0 failures, 0 errors, 0 skips @nateberkopec
36. # test.rb require 'minitest/autorun' @nateberkopec
37. # minitest/autorun.rb require "minitest" # requires minitest/test require "minitest/spec" # requires minitest/expectations require "minitest/mock" Minitest.autorun @nateberkopec
38. # minitest.rb module Minitest # ... snip ... def self.autorun at_exit { next if $! and not ($!.kind_of? SystemExit and $!.success?) exit_code = nil at_exit { @@after_run.reverse_each(&:call) exit exit_code || false } exit_code = Minitest.run ARGV } unless @@installed_at_exit @@installed_at_exit = true end end @nateberkopec
39. def self.autorun if autorun_disabled? RSpec.deprecate("Requiring `rspec/autorun` when running RSpec via the `rspec` command") return elsif installed_at_exit? || running_in_drb? return end at_exit { perform_at_exit } @installed_at_exit = true end def self.perform_at_exit return unless $!.nil? || $!.is_a?(SystemExit) invoke end def self.invoke disable_autorun! status = run(ARGV, $stderr, $stdout).to_i exit(status) if status != 0 end def self.disable_autorun! @autorun_disabled = true end def self.installed_at_exit? @installed_at_exit ||= false end @nateberkopec
40. # RSpec def self.installed_at_exit? @installed_at_exit ||= false end # Minitest @@installed_at_exit = true @nateberkopec
41. Do the Simplest Thing That Could Posibly Work @nateberkopec
42. # Minitest.autorun -> Minitest.run def self.run reporter, options = {} filter = options[:filter] || "/./" filter = Regexp.new $1 if filter =~ %r%/(.*)/% filtered_methods = self.runnable_methods.find_all { |m| filter === m || filter === "#{self}##{m}" } return if filtered_methods.empty? with_info_handler reporter do filtered_methods.each do |method_name| run_one_method self, method_name, reporter end end end @nateberkopec
43. def self.run reporter, options = {} def self.run(reporter, options = {}) def some_method arg1 arg2 arg3 @nateberkopec
44. puts array.delete hash.fetch :foo via David Brady @nateberkopec
45. puts array.delete(hash.fetch(:foo)) @nateberkopec
46. thing_i_want_to_remove = hash.fetch :foo array.delete thing_i_want_to_remove puts thing_i_want_to_remove @nateberkopec
47. Pain is good. Pain is signal. @nateberkopec
48. Test Discovery? @nateberkopec
49. # minitest.rb module Minitest class Runnable # Minitest::Test is a Runnable def self.runnables @@runnables end def self.inherited klass # :nodoc: self.runnables << klass super end end end @nateberkopec
50. class Foo def self.inherited(subclass) puts "New subclass: #{subclass}" end end @nateberkopec
51. # test.rb require 'minitest/autorun' class MyTest < Minitest::Test def test_the_truth assert_equal 1, 1 end end @nateberkopec
52. Stdlib used in Minitest → OptionParser → Thread → Mutex → StringIO → Tempfile @nateberkopec
53. Core/stdlib classes RSpec overrides or re- implements → Set → flat_map → Thread local variables → rand (!!!) @nateberkopec
54. Use what is given. @nateberkopec
55. Defining Tests in Minitest @nateberkopec
56. # Minitest::Test # This was called in Minitest.run def self.runnable_methods methods = methods_matching(/^test_/) #one-liner that returns a list of methods as strings case self.test_order when :random, :parallel then max = methods.size methods.sort.sort_by { rand max } when :alpha, :sorted then methods.sort else raise "Unknown test_order: #{self.test_order.inspect}" end end @nateberkopec
57. define_example_method :example define_example_method :it define_example_method :specify define_example_method :focus, :focus => true define_example_method :fexample, :focus => true define_example_method :fit, :focus => true define_example_method :fspecify, :focus => true define_example_method :xexample, :skip => 'Temporarily skipped with xexample' define_example_method :xit, :skip => 'Temporarily skipped with xit' define_example_method :xspecify, :skip => 'Temporarily skipped with xspecify' define_example_method :skip, :skip => true define_example_method :pending, :pending => true @nateberkopec
58. def self.define_example_method(name, extra_options={}) idempotently_define_singleton_method(name) do |*all_args, &block| desc, *args = *all_args options = Metadata.build_hash_from(args) options.update(:skip => RSpec::Core::Pending::NOT_YET_IMPLEMENTED) unless block options.update(extra_options) example = RSpec::Core::Example.new(self, desc, options, block) examples << example example end end @nateberkopec
59. Reduce the API surface @nateberkopec
60. def assert_includes collection, obj, msg = nil msg = message(msg) { "Expected #{mu_pp(collection)} to include #{mu_pp(obj)}" } assert_respond_to collection, :include? assert collection.include?(obj), msg end @nateberkopec
61. def assert test, msg = nil self.assertions += 1 unless test then msg ||= "Failed assertion, no message given." msg = msg.call if Proc === msg raise Minitest::Assertion, msg end true end @nateberkopec
62. module Minitest module Test include Assertions end end @nateberkopec
63. Rspec: I honestly have no idea @nateberkopec
64. RSpec::Matchers.define :be_a_multiple_of do |expected| match do |actual| actual % expected == 0 end end @nateberkopec
65. Abstraction is the Enemy @nateberkopec
66. A philosophy of pain @nateberkopec
67. MINITEST A PHILOSOPHY OF PAIN Slides @nateberkopec
68. Secrets verbose mode self.makemydiffs_pretty! @nateberkopec
69. Other things that don't exist → stubs (singletons, Liskov Substitution (TestClass versions)) → assertnothingraised → a minitest runner @nateberkopec
70. @nateberkopec