iOS Talks 6: Unit Testing

1. Unit Testing

2. Zašto?

3. Kako ubiti  2 aplikacije Jednim commitom.

4. Manje bugova.

5. Swift   migracija? Nema problema.

6. Manje stresa.

7. Kad se isplati?

8. Testiranje je investicija

9. Što testirati? Koliko se koristi?  Koliko je kompleksno?  Koliko je važna korektnost?

10. Što testirati? 1. Core logika  2. Prezentacija (ViewModel) 3. UI

11. Zašto ljudi ne  testiraju?

12. Testovi su  teški. Ako je dizajn loš.

13. Teško za testirati: Dependency (UIKit, Foundation, libovi)

14. Lagano za  testirati: “Čisti” Swift Business logika

15. Granice Razdvojiti Swift od plaforme i libraryja Izdvojiti logiku aplikacije

16. MVVM

17. UIViewController NAVIGACIJA UIKIT PRIKAZ UI LOGIKA NETWORKING BUSINESS  LOGIKA TRANSFORMA CIJA PODATAKA MIJENJANJE  STANJA

18. UIViewController NAVIGACIJA UIKIT PRIKAZ UI LOGIKA NETWORKINGBUSINESS  LOGIKA TRANSFORMA CIJA PODATAKA MIJENJANJE  STANJA ViewModel

19. MVVM++

20. Example

21. States LoadedLoading No data Error

22. States class FeedViewModel { enum ViewState { case loading case noData case error(String) case loaded([FeedCellModel]) } }

23. Data struct FeedCellModel { let name: String let description: String let image: URL? } Lagano za veriﬁcirati, bez stanja (nepromjenljivo)

24. class FeedViewModel { func loadData() { self.state = .loading feedService.getFeedItem(page: 0) { result in switch result { case let .success(items): if items.isEmpty { self.state = .noData } else { let models = self.feedCellModels(from: items) self.state = .loaded(models) } case let .failure(error): let errorText = self.errorText(for: error) self.state = .error(errorText) } } } }

29. class FeedViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() viewModel.onStateChanged = { [weak self] state in guard let `self` = self else { return } switch state { case .noData: self.refreshControl.endRefreshing() self.manager.data = [] self.errorImage.isHidden = true self.errorLabel.text = Localizable.error_empty_feed self.errorView.isHidden = false case .error(let error): self.manager.data = [] self.refreshControl.endRefreshing() self.errorImage.isHidden = false self.errorLabel.text = error self.errorView.isHidden = false case .loaded(let items): self.refreshControl.endRefreshing() self.manager.data = items self.errorView.isHidden = true case .loading: self.refreshControl.beginRefreshing() } } }

30. Prednosti 1. Cijeli state na jednom mjestu 2. Manipulacija statea izdvojena iz iOS-a 3. Lagano ubacivanje dodatnog   statea

31. Prednosti Testabilan dizajn = dobar dizajn

32. Testiranje 1. Spremi promjenu statea u array. 2. Okini akcije.  3. Provjeri state array.

33. class FeedDetailsViewModelTests: XCTestCase { var feedService: FeedServiceMock! var states: [FeedDetailsViewModel.ViewState] = [] var viewModel: FeedDetailsViewModel! override func setUp() { super.setUp() feedService = FeedServiceMock() states = [] viewModel = FeedViewModel(feedService) viewModel.onState = { self.states.append($0) } }

37. final class FeedDetailsViewModelTests: XCTestCase { // …  func testLoadDataTransitionsToLoadedState() { viewModel.loadData() switch (states.first!, states.last!) { case (.loading, .loaded): break default: XCTFail() } } }

41. final class FeedDetailsViewModelTests: XCTestCase { // …  func testFeedItemData() { viewModel.loadData() switch states.last! { case .loaded(let data): XCTAssertEqual(data, self.feedService.mockFeedItems) default: XCTFail("Expected `loaded`") } } }

45. Rinse and  repeat.

46. Dependencyji

47. Stub / mock Preuzeti kontrolu nad dependencyjem Lakše testiranje

48. 1. Dependency  Injection

49. class PersistenceService { var token: String? { let defaults = UserDefaults.standard return defaults.object(forKey: "user_token") as? String } }

50. class PersistenceService { var token: String? { let defaults = UserDefaults.standard return defaults.object(forKey: "user_token") as? String } } Implicitni dependency

51. class PersistenceService { private let defaults: UserDefaults init(_ defaults: UserDefaults) { self.defaults = defaults } var token: String? { return defaults.object(forKey: "user_token") as? String } }

52. Pozivatelj  kreira   dependency

53. 2. Dependency  Inversion

54. class PersistenceService { private let defaults: UserDefaults init(_ defaults: UserDefaults) { self.defaults = defaults } var token: String? { return defaults.object(forKey: "user_token") as? String } }

55. protocol ObjectStore { func set(value: Any?, forKey: String) func object(forKey: String)-> Any? }

56. protocol ObjectStore { func set(value: Any?, forKey: String) func object(forKey: String)-> Any? } extension UserDefaults: ObjectStore {}

57. class PersistenceService { private let defaults: ObjectStore init(_ defaults: ObjectStore) { self.defaults = defaults } var token: String? { return defaults.object(forKey: "user_token") as? String } }

58. class UserDefaultsMock: ObjectStore { func object(forKey: String) -> Any? { } func set(value: Any?, forKey: String) { } } let userDefaultsMock = UserDefaultsMock() let persistenceService = PersistenceService(userDefaultsMock)

59. class UserDefaultsMock: ObjectStore { var data: [String: Any?] = [:] func object(forKey key: String) -> Any? { return data[key] ?? nil } func set(value: Any?, forKey key: String) { data[key] = value } }

60. final class PersistenceServiceTests: XCTestCase { var store: ObjectStoreMock! var service: PersistenceService! override func setUp() { super.setUp() store = ObjectStoreMock() service = PersistenceService(store) } func testRetrievesSavedTokenFromStore() { store.data["token"] = "savedToken" XCTAssertEqual(service.token, "savedToken") } }

61. Pisanje mockova.

62. class LoginServiceMock: LoginServiceProtocol { func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { } }

63. class LoginServiceMock: LoginServiceProtocol { var loginParameters: (username: String, password: String)? func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { loginParameters = (username, password) } }

64. class LoginServiceMock: LoginServiceProtocol { var loginParameters: (username: String, password: String)? func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { loginParameters = (username, password) } }

65. class LoginServiceMock: LoginServiceProtocol { var loginParameters: (username: String, password: String)? func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { loginParameters = (username, password) } } func testCallsLoginServiceWithCorrectParams() { loginViewModel.login(  email: "[email protected]",   password: "123pass") let expectedParams = ("[email protected]", "123pass") XCTAssertEqual(expectedParams,  loginServiceMock.loginParameters) }

66. var loginShouldSucceed = true func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { if loginShouldSucceed { completion(.success(UserToken(token: "abc123"))) } else { completion(.failure(.noInternet)) } }

67. var loginShouldSucceed = true func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { if loginShouldSucceed { completion(.success(UserToken(token: "abc123"))) } else { completion(.failure(.noInternet)) } }

68. var loginShouldSucceed = true func login(username: String, password: String, completion: @escaping (LoginResult)-> Void) { if loginShouldSucceed { completion(.success(UserToken(token: "abc123"))) } else { completion(.failure(.noInternet)) } } func testHandlesErrorCorrectly() { loginServiceMock.loginShouldSucceed = false loginViewModel.login(email: "[email protected]",   password: "123pass") XCTAssertNotNil(viewModel.errorText) }

69. Sourcery je prijatelj. Link na kraju preze.

70. Pisanje testova

71. Testovi su teški.

72. Dobri testovi su teški.

73. Ne prolazi za ni jednu netočnu implementaciju. 1. Pokrivenost

74. func testHandlesErrorCorrectly() { loginServiceMock.loginShouldSucceed = false loginViewModel.login(email: "[email protected]",   password: "123pass") XCTAssertNotNil(viewModel.errorText) } Prazan string?

75. Test prolazi za sve korektne implementacije. 1. Lakoća refaktoringa

76. func testStoresUsernameCorrectly() { let store = UserDataStore() store.store(username: "Marin") XCTAssertEqual(store.storage["username"], "Marin") }

77. func testStoresUsernameCorrectly() { let store = UserDataStore() store.store(username: "Marin") XCTAssertEqual(store.storage["username"], "Marin") } func testStoresUsernameCorrectly() { let store = UserDataStore() store.store(username: "Marin") XCTAssertEqual(store.storedUsername, "Marin") } vs

78. Korektno + Fleksibilno

79. Tips & tricks

80. Odaberi dobar framework

81. Nek te CI natjera

82. Piši helpere

83. Testiraj nešto

84. Whew!

85. Testing For People Who Hate Testing  https://eev.ee/blog/2016/08/22/testing-for-people-who-hate-testing/ AutoMockable Sourcery template  https://cdn.rawgit.com/krzysztofzablocki/Sourcery/master/docs/mocks.html Unit Testing in Swift  https://medium.cobeisfresh.com/unit-testing-in-swift-part-1-the-philosophy-9bc85ed5001b

iOS Talks 6: Unit Testing

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