Better Code Through Boring(er) Tests

Your tests are annoying. Whenever you update your application code, you need to change a lot of them. You've built yourself some test macros, and some nice FactoryGirl factories, and installed this really cool matcher gem... and your tests are still annoying. What if you changed your application code instead? In this talk, you'll learn what "listening to your tests" means in the real world: no mysticism, no arrogant TDD purism, just a few practical refactorings you can use tomorrow at work.

Transcript

1. better code through boring(er) tests BETSY HAIBEL @betsythemuffin
2. everyone values testing @betsythemuffin
3. TYPE A QUOTE HERE. @betsythemuffin
4. literally no one loves testing all the time ‣not even me ‣it’s ok to admit it ‣the testing police are not coming for you @betsythemuffin
5. GROUNDWORK WHAT WE’RE GONNA DO ABOUT THAT TODAY ▸ learn why we hate our tests :( ▸ learn why we fight about tests :( ▸ learn about ways we accidentally make our tests worse :( ▸ learn how to fix those! ▸ learn how to make our app code better at the same time! @betsythemuffin
6. GROUNDWORK WHAT WE’RE GONNA DO ABOUT THAT TODAY UNDERLYING REASONS @betsythemuffin
7. GROUNDWORK WHAT WE’RE GONNA DO ABOUT THAT TODAY UNDERLYING REASONS SPECIFIC EXAMPLES @betsythemuffin
8. GROUNDWORK WHAT WE’RE GONNA DO ABOUT THAT TODAY UNDERLYING REASONS SPECIFIC EXAMPLES @betsythemuffin
9. GROUNDWORK WHAT WE’RE GONNA DO ABOUT THAT TODAY UNDERLYING REASONS SPECIFIC EXAMPLES @betsythemuffin
10. GROUNDWORK WHAT WE’RE GONNA DO ABOUT THAT TODAY UNDERLYING REASONS SPECIFIC EXAMPLES @betsythemuffin
11. tests are code and are therefore terrible UNDERLYING REASONS @betsythemuffin
12. you write your tests with the same imperfect knowledge as you write all your code UNDERLYING REASONS @betsythemuffin
13. WHY DON’T YOU TRY LISTENING TO YOUR TESTS? some jerk who likes TDD too much THIS IS THE THING THAT ALWAYS HAPPENS. CRIKEY. UNDERLYING REASONS @betsythemuffin
14. 1. TESTS YOU HATE 2. ??? 3. CODE YOU DON’T HATE some jerk who likes TDD too much WE TRANSLATE, WITHOUT EXCESSIVE KINDNESS UNDERLYING REASONS @betsythemuffin
15. UGH I THINK WE CAN FIX THIS IF WE JUST TRY. I PROMISE. a TDDer who is not communicating well yet WE TRANSLATE, WITH SOMEWHAT MORE EMPATHY @betsythemuffin
16. some notes before we get started properly ‣bad code happens ‣bad tests happen ‣this is fine UNDERLYING REASONS @betsythemuffin
17. code is terrible because the world is complex UNDERLYING REASONS @betsythemuffin
18. we invented esoteric testing techniques for good reasons UNDERLYING REASONS @betsythemuffin
19. everything I am about to show you I have done in production especially the parts I say are bad UNDERLYING REASONS @betsythemuffin
20. TESTING PRIVATE METHODS @betsythemuffin
21. @book.send(:dogear) # a private method! TESTING PRIVATE METHODS - THE PROBLEM @betsythemuffin
22. WHY DO PEOPLE TEST PRIVATE METHODS? ▸ indirect results ▸ expensive to test via public interface ▸ weird side effects elsewhere TESTING PRIVATE METHODS - THE PROBLEM @betsythemuffin
23. ALTERNATIVES TO TESTING PRIVATE METHODS ▸ make the method public ▸ build more introspection logic ▸ extract a simple class TESTING PRIVATE METHODS - ALTERNATIVES @betsythemuffin
24. def dogear DogearMaker.new(self).call end class DogearMaker def initialize(target) @target = target end def call # stuff end end TESTING PRIVATE METHODS - EXTRACT SIMPLE CLASS @betsythemuffin
25. it’s ok to fix things later TESTING PRIVATE METHODS - DEFER THE DECISION @betsythemuffin
26. DUPLICATE TESTS @betsythemuffin
27. class ClientTest < Minitest::Test def test_mobile_phones @client.phone_number = MOBILE_PHONE assert @client.mobile_phone? end def test_landline_phones @client.phone_number = LANDLINE_PHONE assert !@client.mobile_phone? end end DUPLICATE TESTS - THE PROBLEM @betsythemuffin
28. def test_mobile_phones @client.phone_number = MOBILE_PHONE assert @client.mobile_phone? end it ‘can have a mobile phone‘ do subject.phone_number = MOBILE_PHONE expect(subject.mobile_phone?).to be(true) end DUPLICATE TESTS - THE PROBLEM @betsythemuffin
29. class ClientTest < Minitest::Test def test_mobile_phones @client.phone_number = MOBILE_PHONE assert @client.mobile_phone? end def test_landline_phones @client.phone_number = LANDLINE_PHONE assert !@client.mobile_phone? end end DUPLICATE TESTS - THE PROBLEM @betsythemuffin
30. class DonorrTest < Minitest::Test def test_mobile_phones @donorr.phone_number = MOBILE_PHONE assert @donorr.mobile_phone? end def test_landline_phones @donorr.phone_number = LANDLINE_PHONE assert !@donorr.mobile_phone? end end DUPLICATE TESTS - THE PROBLEM @betsythemuffin
31. module HasPhoneNumberTest def test_mobile_phones @subjec.phone_number = MOBILE_PHONE assert @subjec.mobile_phone? end def test_landline_phones @subjec.phone_number = LANDLINE_PHONE assert !@subjec.mobile_phone? end end DUPLICATE TESTS - THE SHARED EXAMPLE GROUP SMELL @betsythemuffin
32. class ClientTest < Minitest::Test include HasPhoneNumberTest end class CustomerTest < Minitest::Test include HasPhoneNumberTest end DUPLICATE TESTS - THE SHARED EXAMPLE GROUP SMELL @betsythemuffin
33. class Client include HasPhoneNumber end class Customer include HasPhoneNumber end DUPLICATE TESTS - THE SHARED EXAMPLE GROUP SMELL @betsythemuffin
34. this locks us into assumptions DUPLICATE TESTS - THE SHARED EXAMPLE GROUP SMELL @betsythemuffin
35. class HasPhoneNumberTest < Minitest::Test class HasPhone include HasPhoneNumber end def test_landline_phones @has_phone = HasPhone.new @has_phone.phone_number = LANDLINE_PHONE assert !@has_phone.mobile_phone? end end DUPLICATE TESTS - THE DIRECT MODULE TEST SMELL @betsythemuffin
36. class PhoneNumber attr_accessor :value def mobile_phone? # complicated lookup logic end end DUPLICATE TESTS - THE EXTRACT CLASS FIX @betsythemuffin
37. test duplication sometimes means functional duplication DUPLICATE TESTS - THE KEY IDEA @betsythemuffin
38. INVENTING THE UNIVERSE @betsythemuffin
39. class PieTest < Minitest::Test def test_pie_tastes_good @universe.invent @apple_seed = AppleSeed.new @orchard = Orchard.new @orchard.plant(@apple_seed) @orchard.water! let_much_time_pass @apple_tree = Orchard.find_tree_from(@apple_seed) # etc assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust? end end INVENTING THE UNIVERSE - THE PROBLEM @betsythemuffin
40. class PieTest < Minitest::Test def test_pie_tastes_good # many other lines assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust? end end INVENTING THE UNIVERSE - THE PROBLEM @betsythemuffin
41. first, pretend this isn’t terrible. INVENTING THE UNIVERSE - THE PREMATURE FIX SMELL @betsythemuffin
42. class PieTest < Minitest::Test def test_pie_tastes_good @universe.invent @apple_seed = AppleSeed.new @orchard = Orchard.new @orchard.plant(@apple_seed) @orchard.water! let_much_time_pass @apple_tree = Orchard.find_tree_from(@apple_seed) # etc assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust? end end INVENTING THE UNIVERSE - THE PREMATURE FIX SMELL @betsythemuffin
43. your tests use your application’s assumptions (unless you try very hard) INVENTING THE UNIVERSE - THE PREMATURE FIX SMELL @betsythemuffin
44. wait until you have multiple tests INVENTING THE UNIVERSE - THE PREMATURE FIX SMELL @betsythemuffin
45. shared contexts INVENTING THE UNIVERSE - SHARED CONTEXT SMELL @betsythemuffin
46. class PieTest < Minitest::Test include ReliesOnUniverseExisting def setup invent_universe end end INVENTING THE UNIVERSE - SHARED CONTEXT SMELL @betsythemuffin
47. WHAT ARE SHARED CONTEXTS GOOD FOR? ▸ database setup ▸ inventing the universe INVENTING THE UNIVERSE - SHARED CONTEXT SMELL @betsythemuffin
48. WHAT DO SHARED CONTEXTS HIDE FROM US? ▸ dependencies ▸ (but that’s not the whole story) INVENTING THE UNIVERSE - SHARED CONTEXT SMELL @betsythemuffin
49. factory_girl INVENTING THE UNIVERSE - FACTORY_GIRL SMELL @betsythemuffin
50. FactoryGirl.create(:pie) FactoryGirl.create(:filling) # omg they look the same! INVENTING THE UNIVERSE - FACTORY_GIRL SMELL @betsythemuffin
51. saying “dependencies” is cheating INVENTING THE UNIVERSE - FACTORY_GIRL SMELL @betsythemuffin
52. saying “dependencies” is cheating INVENTING THE UNIVERSE - FACTORY_GIRL SMELL @betsythemuffin
53. “dependencies” just means “code you’re not looking at” INVENTING THE UNIVERSE - FACTORY_GIRL SMELL @betsythemuffin
54. just don’t hide domain logic INVENTING THE UNIVERSE - FACTORY_GIRL SMELL @betsythemuffin
55. # constructor: Pie.new(filling: PumpkinPieFilling.new) INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX @betsythemuffin
56. # constructor: Pie.new(filling: PumpkinPieFilling.new) # factory method on class: Pie.bake_with(PumpkinPieFilling.new) INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX @betsythemuffin
57. # constructor: Pie.new(filling: PumpkinPieFilling.new) # factory method on class: Pie.bake_with(PumpkinPieFilling.new) # java-style factory class factory = PieFactory.new factory.add_filling(PumpkinPieFilling.new) @pie = factory.bake INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX @betsythemuffin
58. Business logic is too important to delegate to framework magic INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX @betsythemuffin
59. class PieTest < Minitest::Test def test_pie_tastes_good @universe.invent @apple_seed = AppleSeed.new @orchard = Orchard.new @orchard.plant(@apple_seed) @orchard.water! let_much_time_pass @apple_tree = Orchard.find_tree_from(@apple_seed) # etc assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust? end end INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX @betsythemuffin
60. @universe.invent @apple_seed = AppleSeed.new @orchard = Orchard.new @orchard.plant(@apple_seed) @orchard.water! let_much_time_pass @apple_tree = Orchard.find_tree_from(@apple_seed) # etc assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust? INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX @orchard = Universe.with_orchard(Apple) @pie = Pie.from(@orchard.fruit) assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust?
61. INVENTING THE UNIVERSE - THE PLAIN FACTORY FIX class PieTest < Minitest::Test def test_pie_tastes_good @orchard = Universe.with_orchard(Apple) @pie = Pie.from(@orchard.fruit) assert @pie.filling_set_properly? assert @pie.cinnamon_level > 6 assert @pie.super_flaky_crust? end end @betsythemuffin
62. A MAGIC TRICK @betsythemuffin
63. A MAGIC TRICK @betsythemuffin
64. this is subjective A MAGIC TRICK @betsythemuffin
65. how do we define boring? A MAGIC TRICK @betsythemuffin
66. i think: code that minimizes assumptions is boring A MAGIC TRICK @betsythemuffin
67. application code influences test code test code influences application code A MAGIC TRICK @betsythemuffin
68. 1. TESTS YOU DON’T HATE 2. REFACTORING 3. CODE YOU DON’T HATE all “listening to your tests” means A CONCLUSION @betsythemuffin
69. SHAMELESS PROMOTION TIME BETSY HAIBEL ▸ @betsythemuffin ▸ betsyhaibel.com ▸ github.com/bhaibel ▸ roostify.com/jobs @betsythemuffin
70. QUESTIONS? you, maybe TEXT @betsythemuffin