Why we are (not) writing tests in iOS

The reason we still aren't writing tests in iOS

Transcript

1. Why we are (not) writing tests in iOS apps by Paul Taykalo, Stanfy Lost in maintenance, by Paul Taykalo, #SE2017 1
2. Plan Lost in maintenance, by Paul Taykalo, #SE2017 2
3. Plan » Types of projects in IOS » Need for tests » Reasons why we aren't writing the tets » Bugs vs tests » How not to write tests with success » Selling tests Lost in maintenance, by Paul Taykalo, #SE2017 3
4. Tests in iOS Industry Lost in maintenance, by Paul Taykalo, #SE2017 4
5. Types of projects in iOS Lost in maintenance, by Paul Taykalo, #SE2017 5
6. Types of projects in iOS » MVP/Pet » Copycat =^.^= » Mastodon » Hyped Unicorn » Own product/Library Lost in maintenance, by Paul Taykalo, #SE2017 6
7. MVP Pet Project GameZ Lost in maintenance, by Paul Taykalo, #SE2017 7
8. Copycat Lost in maintenance, by Paul Taykalo, #SE2017 8
9. Mastodon Lost in maintenance, by Paul Taykalo, #SE2017 9
10. Hyped Unicorn All frameworks all the Things Hyped Social App Lost in maintenance, by Paul Taykalo, #SE2017 10
11. Own product / Library Lost in maintenance, by Paul Taykalo, #SE2017 11
12. Different products Different aproaches Different styles Lost in maintenance, by Paul Taykalo, #SE2017 12
13. Need for tests Lost in maintenance, by Paul Taykalo, #SE2017 13
14. Need for tests » ❌ MVP/Pet/Games » " Copycat » ✅ Mastodon » " Hyped Unicorn » ✅ Own product/Library Lost in maintenance, by Paul Taykalo, #SE2017 14
15. What is the next project you will work on? » MVP/Pet » Copycat » Mastodon » Hyped Unicorn » Own product/Library Lost in maintenance, by Paul Taykalo, #SE2017 15
16. We don't need tests. We work on the projects with short lifetime and they're too small for tests — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 16
17. Growth Lost in maintenance, by Paul Taykalo, #SE2017 17
18. Bugs vs Tests Lost in maintenance, by Paul Taykalo, #SE2017 18
19. Bugs probability depends on » Lifetime » Time between updates » User base » Integrations count » Code base/complexity » Team change Lost in maintenance, by Paul Taykalo, #SE2017 19
20. Reason why we should do write tests Lost in maintenance, by Paul Taykalo, #SE2017 20
21. Time to add tests? Lost in maintenance, by Paul Taykalo, #SE2017 21
22. What tests will we write? 1. UI/Acceptance tests 2. Unit tests 3. Integration tests 4. Snapshot tests Lost in maintenance, by Paul Taykalo, #SE2017 22
23. UI/Acceptance Tests quality Lost in maintenance, by Paul Taykalo, #SE2017 23
24. UI/Acceptance Tests quality » Overfitting » Orange tests » Hard to support test data » Complex running flow » ¯\_(ϑ)_/¯ It works on my machine:) Lost in maintenance, by Paul Taykalo, #SE2017 24
25. Do you hear them? Lost in maintenance, by Paul Taykalo, #SE2017 25
26. Aggressive Snagev Tests Adepts Lost in maintenance, by Paul Taykalo, #SE2017 26
27. We aren't writing tests. We were writing tests, but they were too fragile, and they were breaking for no reason, so we decided not to — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 27
28. Unit tests quality » No modularity - Slow tests » High overfitting chance » Less tend to be fragile, Have the biggest value » Often SUT is not correctly selected Lost in maintenance, by Paul Taykalo, #SE2017 28
29. Tests are slow. It is way easier to run application directly and check — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 29
30. Choose your System Under Test Correctly Lost in maintenance, by Paul Taykalo, #SE2017 30
31. System Under Test Application Lost in maintenance, by Paul Taykalo, #SE2017 31
32. Integration tests quality Lost in maintenance, by Paul Taykalo, #SE2017 32
33. Integration tests quality » Signlentons » Complex tests » Hard to support » Implementation dependent (fragile) Lost in maintenance, by Paul Taykalo, #SE2017 33
34. It's hard to support tests. Once I change something a little I need to rewrite a lot of the tests — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 34
35. Snapshot testing » UI only* » Works for components » Works best with data flow Lost in maintenance, by Paul Taykalo, #SE2017 35
36. Every time new OS released, all my snapshot tests are broken. It's not worth it — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 36
37. Lost in maintenance, by Paul Taykalo, #SE2017 37
38. Tests Expectations vs reality Lost in maintenance, by Paul Taykalo, #SE2017 38
39. Tests Expectations vs reality Lost in maintenance, by Paul Taykalo, #SE2017 39
40. I added tests they didn't help — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 40
41. Tests are not a cure Tests are the insurance Lost in maintenance, by Paul Taykalo, #SE2017 41
42. I spent weeks trying to test UI and failed all deadlines — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 42
43. Some parts are really hard to test Deal with it Lost in maintenance, by Paul Taykalo, #SE2017 43
44. There are a lot of tests, but the code doesn't seem to be better — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 44
45. Tests won't make your code significantly better* Lost in maintenance, by Paul Taykalo, #SE2017 45
46. You still can write ugly code Lost in maintenance, by Paul Taykalo, #SE2017 46
47. Some tips for those who doesn't write tests Lost in maintenance, by Paul Taykalo, #SE2017 47
48. Don't show/require all data YAGNI struct User { let id: String let name: String let address: String let friends: [User] let dogName: String? let hairStyle: HairStyle ... } Lost in maintenance, by Paul Taykalo, #SE2017 48
49. Own Data layer Layer things out class AppApi { func getUser(by id: String) -> SignalProducer<User, AppApiError> } Lost in maintenance, by Paul Taykalo, #SE2017 49
50. Layer things out enum AppApiError: Error { case userNotLoggedIn case serverFeelsBad case subscriptionEnded case unknown(NetworkError) // } Lost in maintenance, by Paul Taykalo, #SE2017 50
51. Layer things out // Struct for showing error imeediately to the user struct UserError { let title: String let message: String // just in some really rare cases let underlyingError: Error } Lost in maintenance, by Paul Taykalo, #SE2017 51
52. Don't allow invalid data struct UserForm { let id: String? let name: String? let lastName: String? } struct User { let id: String let name: String let lastName: String } Lost in maintenance, by Paul Taykalo, #SE2017 52
53. Isolate Order Dependent Code dataSource.addItems(["1","2","3") tableView.insertItems(at indexPaths:[IndexPath]) tableView.deleteItems(at indexPaths:[]) tableView.reloadData() Lost in maintenance, by Paul Taykalo, #SE2017 53
54. Semantic meaning if itemsCount > 4 if user.rating > 200 && user.userName.isNotEmpty if view.tag == 13 Lost in maintenance, by Paul Taykalo, #SE2017 54
55. Unidirectional data flow Lost in maintenance, by Paul Taykalo, #SE2017 55
56. Linear code loginUser(onSuccess: { user in getAllImages(for: user, onSuccess: { images is verify(images: images, onSuccess: { verified, unverified is verifyDeletion(images: unverified, onSuccess: { shouldDelete in }, onFailure: { // TODO Handle it print(error) }) }, onFailure: { // TODO Handle it print(error) }) }, onFailure: { // TODO Handle it print(error) }) }, onFailure: { // TODO Handle it print(error) }) Lost in maintenance, by Paul Taykalo, #SE2017 56
57. Linear code loggeduserRequest .flatMap(.latest, { user in getAllimages(for: user)}) .flatMap(.latest, { images in verify(images: images)}) .flatMap { verified, unverified in askForDeletion(images: unverified)} .filter { shouldDelete in deleteImages(shouldDelete) } Lost in maintenance, by Paul Taykalo, #SE2017 57
58. Decrease amount of possible states » Optionals » BFO (Object) » Exponential number of states » Mutability Lost in maintenance, by Paul Taykalo, #SE2017 58
59. Some tips for those who doesn't write tests » Don't show/require all data » Layer things out » Don't allow invalid data » Semantic meaning » Linear flow » Decrease amount of possible states Lost in maintenance, by Paul Taykalo, #SE2017 59
60. How (not) to fail adding tests Lost in maintenance, by Paul Taykalo, #SE2017 60
61. How (not) to fail adding tests » Read a lot about testing and types of testing » Try to test-first, try to test-last » Determine your core » Isolate features and test them » Start with Unit tests » For Custom UI you can run snapshot testing Lost in maintenance, by Paul Taykalo, #SE2017 61
62. Te$t$ Lost in maintenance, by Paul Taykalo, #SE2017 62
63. - I won't pay additionally for tests - But there'll be bugs - They'll be there even if you write tests! Lost in maintenance, by Paul Taykalo, #SE2017 63
64. Tests just for tests Lost in maintenance, by Paul Taykalo, #SE2017 64
65. Tests readiness Lost in maintenance, by Paul Taykalo, #SE2017 65
66. I'm not paying you for bug fixes! — angry customer Lost in maintenance, by Paul Taykalo, #SE2017 66
67. How not to go into this conversation Lost in maintenance, by Paul Taykalo, #SE2017 67
68. How not to go into this conversation » React fast » Notify client about changes » Have support plan (include support as an option) » Always assume your code is not working -- prove it otherwise! » It's not fixed until it's checked (see tests) » Acceptance rules (Hard case) Lost in maintenance, by Paul Taykalo, #SE2017 68
69. There are many ways to write an application. We're not building spaceships, you know? — Unknown programmer Lost in maintenance, by Paul Taykalo, #SE2017 69
70. Thank you Lost in maintenance, by Paul Taykalo, #SE2017 70
71. Why we are (not) writing tests in iOS apps by Paul Taykalo, Stanfy @TT_Kilew Lost in maintenance, by Paul Taykalo, #SE2017 71
72. The end Lost in maintenance, by Paul Taykalo, #SE2017 72
73. Bonus Building a Swift Quiz App with TDD and Modular Design https://goo.gl/cUzTkr Lost in maintenance, by Paul Taykalo, #SE2017 73
74. Links http://merowing.info/2017/01/testing-ios-apps/ https://www.swiftbysundell.com/posts/testing-swift-code- that-uses-system-singletons-in-3-easy-steps? utmcontent=buffer1765f&utmmedium=social&utmsource=twitter.co m&utmcampaign=buffer https://www.joelonsoftware.com/2001/07/31/hard-assed-bug- fixin/ Lost in maintenance, by Paul Taykalo, #SE2017 74
75. More links https://medium.com/essential-developer-ios Lost in maintenance, by Paul Taykalo, #SE2017 75