Developing And Testing Complex Permission Flows

For video at LinkedIn Veronica and her team members have to ask for camera, photo library and microphone permissions. She will cover how they abstracted this code into a shared helper and ensured it was well tested. They ran into interesting challenges with testing all the possible cases of users interacting with the permissions dialogues.

This talk will cover how they solved these challenges and what approach they took.

Presented at iOS Conf SG in Singapore on October 20th, 2017

Transcript

1. Building And Tes-ng Complex Permission Flows Veronica Ray Senior So-ware Engineer at LinkedIn
2. Video • Camera • Photo library • Microphone
4. Implemen'ng A Complex Permissions Flow
5. First Problem: Permissions Code Has Weird Bugs
7. Bug Report #456612 HELP! I uploaded a video from my camera roll and when I play it back in the app it has no sound.
8. vray: A member is saying they can't hear sound for a video they uploaded from their camera roll [REDACTED]: Have you checked out the HLS stream? vray: Yeah, the video has sound [REDACTED]: I know this sounds obvious, but did you ask them if volume is turned up on their phones? vray: They said it was. We really need to focus on fixing [REDACTED] issue right now so I'm just gonna close this as cannot reproduce
9. Hey it's video iOS on call here. I haven't been been able to reproduce this issue. Let us know if you run into it again. jira-status: closed
10. The Mystery Of The Bug That Couldn't Be Reproduced
11. Second Problem: Permissions Code Is All Over The Place
15. First Solu+on: Create A Shared Helper
16. public static let shared = PermissionsHelper() private let photoLibrary: PHPhotoLibraryWrapper private let avCaptureDevice: AVCaptureDeviceWrapper private let avAudioSession: AVAudioSessionWrapper init(photoLibrary: PHPhotoLibraryWrapper = PHPhotoLibraryWrapper(), avCaptureDevice: AVCaptureDeviceWrapper = AVCaptureDeviceWrapper(), avAudioSession: AVAudioSessionWrapper = AVAudioSessionWrapper()) { self.photoLibrary = photoLibrary self.avCaptureDevice = avCaptureDevice self.avAudioSession = avAudioSession }
17. public enum PermissionType { case photoLibrary case camera case microphone var noAccessAlertTitle: String { switch self { case .photoLibrary: return StringConstant.noPhotoLibraryAccessAlertTitle case .camera: return StringConstant.noCameraAccessAlertTitle case .microphone: return StringConstant.noMicrophoneAccessAlertTitle } } var noAccessAlertMessage: String { switch self { case .photoLibrary: return StringConstant.noPhotoLibraryAccessAlertMessage case .camera: return StringConstant.noCameraAccessAlertMessage case .microphone: return StringConstant.noMicrophoneAccessAlertMessage } } }
18. private func requestMicrophoneAccessPermission(fromViewController viewController: UIViewController, completion: @escaping (Bool) -> Void) { let status = avAudioSession.recordPermission() switch status { case AVAudioSessionRecordPermission.undetermined: avAudioSession.requestRecordPermission { (granted: Bool) -> Void in if granted { completion(true) } else { self.displayNoAccessAlert(ofType: .microphone, fromViewController: viewController, cancelHandler: { _ in completion(false) }) } } // handle denied and granted case } }
19. Real Alerts vs Fake Alerts
22. You Get One Shot Per Install
23. Just Show A Fake Alert A1er The Real Alert
24. UI Quirks • You won't be able to deep link into app se3ngs using your "fake" alert if you don't ask the system alert first • You'll go to the phone se3ngs instead
26. func launchAppSpecificSettings() { guard let urlString = URL(string: UIApplicationOpenSettingsURLString) else { return } UIApplication.shared.openURL(urlString) }
27. UIApplica)onOpenSe/ngsURLString Used to create a URL that you can pass to the openURL(_:) method. When you open the URL built from this string, the system launches the Se@ngs app and displays the app’s custom se@ngs, if it has any.
28. Tricky Bit When changing the permissions in device se2ngs, the app resets to the ini4al start of the app. For us, that's the feed.
29. Don't Be Alarmed If Xcode Crashes When You Do This In The Simulator
30. Permissions Code Is S.ll Kinda All Over The Place
31. Design Best Prac.ces • Ask for permissions only when you need them • If permissions are necessary for the experience, don't let the user proceed without them • If permissions aren't necessary, let them proceed without them
32. Second Solu*on: Automated Tes,ng
34. func testCompletionShouldSucceedForMicrophoneAccessGranted() { let mockAVAudioSessionWrapper = MockAVAudioSessionWrapper(status: .undetermined, grantedMicrophoneAccess: true) let mockPermissionsHelper = MockPermissionsHelper(avAudioSession: mockAVAudioSessionWrapper) var completionSucceeds = 0 mockPermissionsHelper.requestAccessPermission(ofType: .microphone, fromViewController: UIViewController(), completion: { success in if success { completionSucceeds += 1 } XCTAssertEqual(completionSucceeds, 1, "Completion did not succeed once") }) }
35. private class MockPHPhotoLibraryWrapper: PhotoLibraryWrapping { let status: PHAuthorizationStatus public init(status: PHAuthorizationStatus) { self.status = status } func requestAuthorization(_ handler: @escaping (PHAuthorizationStatus) -> Void) { handler(status) } }
36. What Must Be Scenario Tested?
37. One Big Wrinkle (That You Will Probably Not Need To Deal With)
38. Hardware Features That Are Not Simulated • Mo$on support (accelerometer and gyroscope) • Audio and video input (camera and microphone) • Proximity sensor • Barometer • Ambient light sensor
39. KIF /*! @abstract If present, dismisses a system alert with the last bu:on, usually 'Allow'. Returns YES if a dialog was dismissed, NO otherwise. @discussion Use this to dissmiss a locaGon services authorizaGon dialog or a photos access dialog by tapping the 'Allow' bu:on. No acGon is taken if no alert is present. */ - (BOOL)acknowledgeSystemAlert;
40. EarlGrey • Cannot interact with system alert dialog • Team sees this as a known issue and plans to implemet it in the future
41. XCUITest • Can interact by tapping on certain bu1ons of the alert
43. func testNoCameraAccessOnTapCamera() { // Step 1 let noPhotoAccessAlertHandler = makeUIInteruptionMonitor(of: .photoLibrary, accessGranted: true) app.otherElements["feed"].buttons["feed_open_share_box_camera_button"].tap() // Step 2 app.collectionViews["feed_photo_picker_collection"].cells["photo_picker_camera_cell"].tap() removeUIInterruptionMonitor(noPhotoAccessAlertHandler) // Step 3 let noCameraAccessAlertHandler = makeUIInteruptionMonitor(of: .camera, accessGranted: false) // Step 4 let cancelButton = app.scrollViews.buttons["Cancel"] cancelButton.tap() removeUIInterruptionMonitor(noCameraAccessAlertHandler) // Step 5 let photoPickerTitle = app.staticTexts["feed_photo_picker_title"] waitForElement(element: photoPickerTitle) verifyOnMainCameraRollScreen() }
44. makeUIInteruptionMonitor(of: .photoLibrary, accessGranted: true)
45. Stop System Alerts In Their Tracks
46. class VoyagerXCUITestCase: XCTestCase { public func makeUIInteruptionMonitor(of type: AccessHandlerType, accessGranted: Bool) -> NSObjectProtocol { // Describes purpose of handler mainly used for debugging var alertHandlerDescription: String switch type { case .photoLibrary: alertHandlerDescription = "No Photo Access Alert Handler" case .camera: alertHandlerDescription = "No Camera Access Alert Handler" case .microphone: alertHandlerDescription = "No Microphone Access Alert Handler" } return addUIInterruptionMonitor(withDescription: alertHandlerDescription, handler: { (alert) -> Bool in if alert.buttons["OK"].exists && accessGranted { alert.buttons["OK"].tap() return true } else if alert.buttons["Don't Allow"].exists && !accessGranted { alert.buttons["Don't Allow"].tap() return true } else { return false } }) } }
47. When You're Done, Reset The Permissions
48. class Springboard { static let shared = Springboard() let springboardApp = XCUIApplication(privateWithPath: nil, bundleID: "com.apple.springboard")! private init() { } func resetLocationAndPrivacySettings() { XCUIApplication().terminate() let springboardApp = self.springboardApp springboardApp.resolve() let settingsIcon = springboardApp.icons["Settings"] if settingsIcon.exists { // Go to Home Thread.sleep(forTimeInterval: 0.5) XCUIDevice.shared().press(.home) Thread.sleep(forTimeInterval: 0.5) XCUIDevice.shared().press(.home) Thread.sleep(forTimeInterval: 0.5) // Go to Settings settingsIcon.tap() let settings = XCUIApplication(privateWithPath: nil, bundleID: "com.apple.Preferences")! // Reset Location & Privacy Settings settings.tables.staticTexts["General"].tap() settings.tables.staticTexts["Reset"].tap() settings.tables.staticTexts["Reset Location & Privacy"].tap() Thread.sleep(forTimeInterval: 0.5) settings.buttons["Reset Settings"].tap() settings.terminate() } } }
49. Tricky Bits • In order for the alert handler to fire, you must interact with the app a8er crea9ng the UIInterrup9onMonitor (ex. tap on a buAon) • Make sure to remove the handler once you're done. Otherwise the same handler will be invoked for any other alerts that appear.
50. app.otherElements["feed"].buttons["feed_open_share_box_camera_button"].tap()
52. Iden%fying Elements
53. Fake Alerts vs Real Alerts
54. Fake Alerts • UIAlertController • Does not have customizable accessibility iden:fiers • Use UI Recording in Xcode to find the iden:fiers for its bu@ons
55. UI Recording
56. What To Do About The Se#ngs Bu*on?!
57. Poten&al Solu&ons • Mock the ac+on bu/on to not actually take the user to Se5ngs but to act as if the status has been changed • Perform ac+ons, kill app, then relaunch app with the new se5ngs
58. Changing The Se+ngs • Kills and relaunches the app • Func2onally equivalent to running a different scenario test that tests a different permission status.
59. Our Work Here Is Done
60. iOS 11 Changes To Photo Permissions • Apps using the na.ve picker no longer have to request access to the user’s en.re library to import just one photo or video. User selec.on of a photo or video is an implied permission. No alert is shown. • For apps with custom UIs, the old alert is s.ll shown. • Write permissions now have their own alert.
61. Poorly Tested And Unorganized Permissions Code Leads To
62. Unsolved Mysteries
63. Thank You