Async network logic testing using Protocol (Test Stub)

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Wooseong Kim, StyleShare Async network logic testing using Protocol Session 2 #swiftkorea Testing

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Problems in networking logic testing Concept - Test Stub Case study (with Test Stub)

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Problems in networking logic testing

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Want to test here

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Want to test here But it’s hard

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Because of this!

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What if… Offline? Network problem? Server issue? Auth issues?

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What if… Offline? Network problem? Server issue? Auth issues?

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What if… Offline? Network problem? Server issue? Auth issues?

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What if… Offline? Network problem? Server issue? Auth issues?

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Offline? Network problem? Server issue? Auth issues? What if…

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If the network fails, tests will fail too. What if…

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If the network fails, tests will fail too. What if… Unhappy

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Expected Real world →

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Expected Solution →

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Fake networking?

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Fake Networking Request Response Request Response Same response for same request.

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Fake Networking Useful in test environment Production Testing

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Called Test Stub Production Testing

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So today’s real topic is,

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Wooseong Kim, StyleShare #swiftkorea Testing Async network logic testing using Test Stub Session 2

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Case study (with Test Stub)

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Case study - Log In

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Log-In Button Tap ID/PW Response HTTP Request HTTP Response

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Test Stub → ID/PW Response Testing environments Log-In Button Tap

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Structures

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Production vs Test

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Production vs Test Different operation, but same interface

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Production vs Test …so they can conform the same protocol!

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Production vs Test Difference service on different environment

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Codes

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protocol AuthServiceType { func logIn(id: String, pw: String, ...) }

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protocol AuthServiceType { func logIn(id: String, pw: String, ...) } // Production class AuthService: AuthServiceType { func logIn(id: String, pw: String, ...) { // Networking logic } }

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protocol AuthServiceType { func logIn(id: String, pw: String, ...) } // Production class AuthService: AuthServiceType { func logIn(id: String, pw: String, ...) { // Networking logic } } // Test class StubAuthService: AuthServiceType { func logIn(id: String, pw: String, ...) { // Stub logic } }

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// Production class LogInViewController: UIViewController { var authService: AuthServiceType! ... } let viewController = LogInViewController() viewController.authService = AuthService() // Test let viewController = LogInViewController() viewController.authService = StubAuthService()

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Writing test code with StubAuthService

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// Should store the token after logged in class LogInViewController: UIViewController { ... }

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// Should store the token after logged in class LogInViewController: UIViewController { var authService: AuthServiceType! func logInButtonDidTap() { authService.logIn(id: "id", pw: "pw", completion: { response in // Completion logic } } }

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protocol AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) } // Production class AuthService: AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) { // Networking logic } } // Test class StubAuthService: AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) { // Stub logic } }

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// Test class StubAuthService: AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) { let response = Response(token: "token") // Works synchronously completion(response) } }

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// Test class StubAuthService: AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) { let response = Response(token: "token") completion(response) } } // Production class LogInViewController: UIViewController { func logInButtonDidTap() { authService.logIn(id: "id", pw: "pw", completion: { response in // Passed to here! } } }

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func testLogIn() { ...? }

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func testLogIn() { // given let viewController = LogInViewController() viewController.authService = StubAuthService() }

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func testLogIn() { // given let viewController = LogInViewController() viewController.authService = StubAuthService() // when viewController.logInButtonDidTap() }

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func testLogIn() { // given let viewController = LogInViewController() viewController.authService = StubAuthService() // when viewController.logInButtonDidTap() // then XCTAssertEqual(viewController.token, "token") }

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// Production class LogInViewController: UIViewController { var authService: AuthServiceType! var token: String func logInButtonDidTap() { authService.logIn(id: "id", pw: "pw", completion: { response in self.token = response.token } } }

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Various cases of response - Success or Failure (Wrong password)

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class StubAuthService: AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) { let response = Response(token: "token") // Success case completion(response) } }

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class StubAuthService: AuthServiceType { func logIn(id: String, pw: String, completion: (Response) -> Void) { let response = Response(token: "token") // Success case completion(response) } } func testLogIn_success() { ... XCTAssertEqual(viewController.token, "token") } func testLogIn_wrongPassword() { ...? }

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class StubAuthService: AuthServiceType { var stubResponse: Response! func logIn(id: String, pw: String, completion: (Response) -> Void) { completion(stubResponse) } }

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class StubAuthService: AuthServiceType { var stubResponse: Response! func logIn(id: String, pw: String, completion: (Response) -> Void) { completion(stubResponse) } } func testLogIn_success() { let authService = StubAuthService() authService.stubResponse = Response(token: "token") ... viewController.logInButtonDidTap() XCTAssertEqual(viewController.token, "token") }

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class StubAuthService: AuthServiceType { var stubResponse: Response! func logIn(id: String, pw: String, completion: (Response) -> Void) { completion(stubResponse) } } func testLogIn_success() { ... } func testLogIn_wrongPassword() { let authService = StubAuthService() authService.stubResponse = Response(error: LogInError.wrongPassword) ... viewController.logInButtonDidTap() XCTAssertEqual(viewController.logInError, LogInError.wrongPassword) }

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class StubAuthService: AuthServiceType { var stubResponse: Response! func logIn(id: String, pw: String, completion: (Response) -> Void) { completion(stubResponse) } } func testLogIn_success() { ... } func testLogIn_wrongPassword() { let authService = StubAuthService() authService.stubResponse = Response(error: LogInError.wrongPassword) ... viewController.logInButtonDidTap() XCTAssertEqual(viewController.logInError, LogInError.wrongPassword) }

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enum LogInError { case wrongPassword case idNotExist } class LogInViewController: UIViewController { var authService: AuthServiceType! var token: String var logInError: LogInError func logInButtonDidTap() { authService.logIn(id: "id", pw: "pw", completion: { response in if response.status == .success { self.token = response.token } else if response.status == .failure { self.logInError = response.error } } } }

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Stubber

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Stubber created by @devxoul Stubber

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Stubber is a minimal method stub for Swift.

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Stubber is a minimal method stub for Swift. https://github.com/devxoul/Stubber

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Summary Tests may fail because of network dependency …so let’s write test codes with Test Stub May the Test Stub be with you.

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Thank you! Wooseong Kim, StyleShare [email protected] #swiftkorea