Make LinkNewDeviceScreen fall back to the App Lock PIN code when there's no passcode. (#5794)

* Fall back to the AppLock PIN code when there's no passcode.

* Add extra tests on the LinkNewDeviceFlowCoordinator.

* Misc tweaks for clarification.

* Regenerate snapshots.

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenCoordinator.swift

@@ -11,6 +11,7 @@ import SwiftUI
 enum LinkNewDeviceScreenCoordinatorAction {
     case linkMobileDevice(LinkNewDeviceService.LinkMobileProgressPublisher)
     case linkDesktopComputer
+    case verifyWithAppLockPIN(CheckedContinuation<Bool, Never>)
     case dismiss
 }
 
@@ -47,6 +48,8 @@ final class LinkNewDeviceScreenCoordinator: CoordinatorProtocol {
                 actionsSubject.send(.linkMobileDevice(progressPublisher))
             case .linkDesktopComputer:
                 actionsSubject.send(.linkDesktopComputer)
+            case .verifyWithAppLockPIN(let continuation):
+                actionsSubject.send(.verifyWithAppLockPIN(continuation))
             case .dismiss:
                 actionsSubject.send(.dismiss)
             }

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenModels.swift

@@ -10,6 +10,7 @@ import Foundation
 enum LinkNewDeviceScreenViewModelAction {
     case linkMobileDevice(LinkNewDeviceService.LinkMobileProgressPublisher)
     case linkDesktopComputer
+    case verifyWithAppLockPIN(CheckedContinuation<Bool, Never>)
     case dismiss
 }
 

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenViewModel.swift

@@ -72,8 +72,10 @@ class LinkNewDeviceScreenViewModel: LinkNewDeviceScreenViewModelType, LinkNewDev
         case .verified, .unavailable:
             break
         case .appLockPINRequired:
-            // Follow-up PR: present the App Lock PIN screen to verify the device owner.
-            return
+            guard await verifyWithAppLockPIN() else {
+                state.mode = .readyToLink(.idle)
+                return
+            }
         case .cancelled, .unverified:
             state.mode = .readyToLink(.idle)
             return
@@ -92,6 +94,13 @@ class LinkNewDeviceScreenViewModel: LinkNewDeviceScreenViewModelType, LinkNewDev
         }
     }
     
+    /// Asks the coordinator to verify the device owner with the App Lock PIN, suspending until it has a result.
+    private func verifyWithAppLockPIN() async -> Bool {
+        await withCheckedContinuation { continuation in
+            actionsSubject.send(.verifyWithAppLockPIN(continuation))
+        }
+    }
+    
     private func linkMobileDevice() async {
         state.mode = .readyToLink(.generatingCode)