Remove eraseToStream now that any AsyncSequence is available to us. (#4836)

* Remove `eraseToStream` now that `any AsyncSequence` is available to us.

* Remove the now unnecessary backport of Mutex.

* Silence a couple more deprecation warnings.

ElementX/Sources/AccessibilityTests/AccessibilityTestsAppCoordinator.swift

@@ -154,8 +154,8 @@ struct PreviewsWrapperView: View {
                 // this is a temporary solution
                 .timeout(.seconds(1), scheduler: DispatchQueue.main)
                 .values.first { $0 == true }
-        case .stream(let stream):
-            _ = await stream.first { $0 == true }
+        case .sequence(let sequence):
+            _ = await sequence.first { $0 == true }
         case .none:
             break
         }

ElementX/Sources/Other/Extensions/AsyncSequence.swift

@@ -10,19 +10,4 @@ extension AsyncSequence {
     func first() async rethrows -> Self.Element? {
         try await first { _ in true }
     }
-    
-    /// Type-erases the sequence into a newly constructed asynchronous stream. This is useful until
-    /// we drop support for iOS 17, at which point we can replace this with `any AsyncSequence`.
-    @available(iOS, deprecated: 18.0, message: "Use `any AsyncSequence` instead.")
-    func eraseToStream() -> AsyncStream<Element> {
-        var asyncIterator = makeAsyncIterator()
-        return AsyncStream<Element> {
-            do {
-                return try await asyncIterator.next()
-            } catch {
-                MXLog.warning("Stopping stream: \(error)")
-                return nil
-            }
-        }
-    }
 }

ElementX/Sources/Other/Extensions/Observable.swift

@@ -7,7 +7,7 @@
 //
 
 import Foundation
-import Mutex
+import Synchronization
 
 extension Observable {
     /// Creates an async stream for the specified property on this object. We probably won't need this once SE-0475 is available:

ElementX/Sources/Other/Extensions/Snapshotting.swift

@@ -34,7 +34,7 @@ struct SnapshotFulfillmentPreferenceKey: PreferenceKey {
     
     enum Source {
         case publisher(AnyPublisher<Bool, Never>)
-        case stream(AsyncStream<Bool>)
+        case sequence(any AsyncSequence<Bool, Never>)
     }
     
     struct Wrapper: Equatable {
@@ -69,14 +69,14 @@ extension SwiftUI.View {
     /// These preferences can then be retrieved and used elsewhere in your view hierarchy.
     ///
     /// - Parameters:
-    ///   - expect: A stream that indicates when the preview is ready for snapshotting.
+    ///   - expect: An async sequence that indicates when the preview is ready for snapshotting.
     ///   - precision: The percentage of pixels that must match.
     ///   - perceptualPrecision: The percentage a pixel must match the source pixel to be considered a match. 98-99% mimics the precision of the human eye.
-    func snapshotPreferences(expect fulfillmentStream: AsyncStream<Bool>? = nil,
+    func snapshotPreferences(expect fulfillmentSequence: (any AsyncSequence<Bool, Never>)? = nil,
                              precision: Float = 1.0,
                              perceptualPrecision: Float = 0.98) -> some SwiftUI.View {
         preference(key: SnapshotPrecisionPreferenceKey.self, value: precision)
             .preference(key: SnapshotPerceptualPrecisionPreferenceKey.self, value: perceptualPrecision)
-            .preference(key: SnapshotFulfillmentPreferenceKey.self, value: fulfillmentStream.map { SnapshotFulfillmentPreferenceKey.Wrapper(source: .stream($0)) })
+            .preference(key: SnapshotFulfillmentPreferenceKey.self, value: fulfillmentSequence.map { SnapshotFulfillmentPreferenceKey.Wrapper(source: .sequence($0)) })
     }
 }

ElementX/Sources/Other/Extensions/XCTestCase.swift

@@ -49,23 +49,23 @@ extension XCTestCase {
         }
     }
     
-    /// XCTest utility that assists in observing an async stream, deferring the fulfilment and results until some condition has been met.
+    /// XCTest utility that assists in observing an async sequence, deferring the fulfilment and results until some condition has been met.
     /// - Parameters:
-    ///   - asyncStream: The stream to wait on.
+    ///   - asyncSequence: The sequence to wait on.
     ///   - timeout: A timeout after which we give up.
     ///   - message: An optional custom expectation message
     ///   - until: callback that evaluates outputs until some condition is reached
-    /// - Returns: The deferred fulfilment to be executed after some actions and that returns the result of the stream.
-    func deferFulfillment<Value>(_ asyncStream: AsyncStream<Value>,
+    /// - Returns: The deferred fulfilment to be executed after some actions and that returns the result of the sequence.
+    func deferFulfillment<Value>(_ asyncSequence: any AsyncSequence<Value, Never>,
                                  timeout: TimeInterval = 10,
                                  message: String? = nil,
                                  until condition: @escaping (Value) -> Bool) -> DeferredFulfillment<Value> {
         var result: Result<Value, Error>?
-        let expectation = expectation(description: message ?? "Awaiting stream")
+        let expectation = expectation(description: message ?? "Awaiting sequence")
         var hasFulfilled = false
         
         let task = Task {
-            for await value in asyncStream {
+            for await value in asyncSequence {
                 if condition(value), !hasFulfilled {
                     result = .success(value)
                     expectation.fulfill()
@@ -77,7 +77,7 @@ extension XCTestCase {
         return DeferredFulfillment<Value> {
             await self.fulfillment(of: [expectation], timeout: timeout)
             task.cancel()
-            let unwrappedResult = try XCTUnwrap(result, "Awaited stream did not produce any output")
+            let unwrappedResult = try XCTUnwrap(result, "Awaited sequence did not produce any output")
             return try unwrappedResult.get()
         }
     }
@@ -108,19 +108,19 @@ extension XCTestCase {
         return deferred
     }
     
-    /// XCTest utility that assists in subscribing to an async stream and deferring the fulfilment and results until some other actions have been performed.
+    /// XCTest utility that assists in subscribing to an async sequence and deferring the fulfilment and results until some other actions have been performed.
     /// - Parameters:
-    ///   - asyncStream: The stream to wait on.
-    ///   - transitionValues: the values through which the stream needs to transition through
+    ///   - asyncSequence: The sequence to wait on.
+    ///   - transitionValues: the values through which the sequence needs to transition through
     ///   - timeout: A timeout after which we give up.
     ///   - message: An optional custom expectation message
-    /// - Returns: The deferred fulfilment to be executed after some actions and that returns the result of the stream.
-    func deferFulfillment<Value: Equatable>(_ asyncStream: AsyncStream<Value>,
+    /// - Returns: The deferred fulfilment to be executed after some actions and that returns the result of the sequence.
+    func deferFulfillment<Value: Equatable>(_ asyncSequence: any AsyncSequence<Value, Never>,
                                             transitionValues: [Value],
                                             timeout: TimeInterval = 10,
                                             message: String? = nil) -> DeferredFulfillment<Value> {
         var expectedOrder = transitionValues
-        let deferred = deferFulfillment(asyncStream, timeout: timeout, message: message) { value in
+        let deferred = deferFulfillment(asyncSequence, timeout: timeout, message: message) { value in
             if let index = expectedOrder.firstIndex(where: { $0 == value }), index == 0 {
                 expectedOrder.remove(at: index)
             }
@@ -159,23 +159,23 @@ extension XCTestCase {
         }
     }
     
-    /// XCTest utility that assists in subscribing to an async stream and deferring the failure for a particular value until some other actions have been performed.
+    /// XCTest utility that assists in subscribing to an async sequence and deferring the failure for a particular value until some other actions have been performed.
     /// - Parameters:
-    ///   - asyncStream: The stream to wait on.
+    ///   - asyncSequence: The sequence to wait on.
     ///   - timeout: A timeout after which we give up.
     ///   - message: An optional custom expectation message
     ///   - until: callback that evaluates outputs until some condition is reached
-    /// - Returns: The deferred fulfilment to be executed after some actions. The stream's result is not returned from this fulfilment.
-    func deferFailure<Value>(_ asyncStream: AsyncStream<Value>,
+    /// - Returns: The deferred fulfilment to be executed after some actions. The sequence's result is not returned from this fulfilment.
+    func deferFailure<Value>(_ asyncSequence: any AsyncSequence<Value, Never>,
                              timeout: TimeInterval,
                              message: String? = nil,
                              until condition: @escaping (Value) -> Bool) -> DeferredFulfillment<Void> {
-        let expectation = expectation(description: message ?? "Awaiting stream")
+        let expectation = expectation(description: message ?? "Awaiting sequence")
         expectation.isInverted = true
         var hasFulfilled = false
         
         let task = Task {
-            for await value in asyncStream {
+            for await value in asyncSequence {
                 if condition(value), !hasFulfilled {
                     expectation.fulfill()
                     hasFulfilled = true

ElementX/Sources/Screens/Authentication/LoginScreen/View/LoginScreen.swift

@@ -137,13 +137,13 @@ struct LoginScreen_Previews: PreviewProvider, TestablePreview {
         NavigationStack {
             LoginScreen(context: viewModel.context)
         }
-        .snapshotPreferences(expect: viewModel.context.observe(\.viewState.homeserver.loginMode).map { $0 == .password }.eraseToStream())
+        .snapshotPreferences(expect: viewModel.context.observe(\.viewState.homeserver.loginMode).map { $0 == .password })
         .previewDisplayName("Initial State")
         
         NavigationStack {
             LoginScreen(context: credentialsViewModel.context)
         }
-        .snapshotPreferences(expect: credentialsViewModel.context.observe(\.viewState.homeserver.loginMode).map { $0 == .password }.eraseToStream())
+        .snapshotPreferences(expect: credentialsViewModel.context.observe(\.viewState.homeserver.loginMode).map { $0 == .password })
         .previewDisplayName("Credentials Entered")
         
         NavigationStack {

ElementX/Sources/Screens/EmojiPickerScreen/View/EmojiPickerScreen.swift

@@ -109,7 +109,7 @@ struct EmojiPickerScreen_Previews: PreviewProvider, TestablePreview {
     static var previews: some View {
         EmojiPickerScreen(context: viewModel.context)
             .previewDisplayName("Screen")
-            .snapshotPreferences(expect: viewModel.context.observe(\.viewState.categories).map { !$0.isEmpty }.eraseToStream())
+            .snapshotPreferences(expect: viewModel.context.observe(\.viewState.categories).map { !$0.isEmpty })
     }
 }
 

ElementX/Sources/Screens/FilePreviewScreen/View/TimelineMediaPreviewDetailsView.swift

@@ -185,7 +185,7 @@ struct TimelineMediaPreviewDetailsView_Previews: PreviewProvider, TestablePrevie
         if case let .media(mediaItem) = viewModel.state.currentItem {
             TimelineMediaPreviewDetailsView(item: mediaItem, context: viewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Image")
-                .snapshotPreferences(expect: mediaItem.observe(\.fileHandle).map { $0 != nil }.eraseToStream())
+                .snapshotPreferences(expect: mediaItem.observe(\.fileHandle).map { $0 != nil })
         }
         
         if case let .media(mediaItem) = loadingViewModel.state.currentItem {
@@ -196,13 +196,13 @@ struct TimelineMediaPreviewDetailsView_Previews: PreviewProvider, TestablePrevie
         if case let .media(mediaItem) = unknownTypeViewModel.state.currentItem {
             TimelineMediaPreviewDetailsView(item: mediaItem, context: unknownTypeViewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Unknown type")
-                .snapshotPreferences(expect: mediaItem.observe(\.fileHandle).map { $0 != nil }.eraseToStream())
+                .snapshotPreferences(expect: mediaItem.observe(\.fileHandle).map { $0 != nil })
         }
         
         if case let .media(mediaItem) = presentedOnRoomViewModel.state.currentItem {
             TimelineMediaPreviewDetailsView(item: mediaItem, context: presentedOnRoomViewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Incoming on Room")
-                .snapshotPreferences(expect: mediaItem.observe(\.fileHandle).map { $0 != nil }.eraseToStream())
+                .snapshotPreferences(expect: mediaItem.observe(\.fileHandle).map { $0 != nil })
         }
     }
     

ElementX/Sources/Screens/Onboarding/IdentityConfirmationScreen/View/IdentityConfirmationScreen.swift

@@ -127,7 +127,7 @@ struct IdentityConfirmationScreen_Previews: PreviewProvider, TestablePreview {
         .previewDisplayName("Actions")
         .snapshotPreferences(expect: viewModel.context.observe(\.viewState.availableActions).map { actions in
             actions?.contains([.interactiveVerification, .recovery]) == true
-        }.eraseToStream())
+        })
         
         NavigationStack {
             IdentityConfirmationScreen(context: loadingViewModel.context)

ElementX/Sources/Screens/RoomDetailsScreen/View/RoomDetailsScreen.swift

@@ -339,23 +339,23 @@ struct RoomDetailsScreen_Previews: PreviewProvider, TestablePreview {
     
     static var previews: some View {
         RoomDetailsScreen(context: genericRoomViewModel.context)
-            .snapshotPreferences(expect: genericRoomViewModel.context.observe(\.viewState.permalink).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: genericRoomViewModel.context.observe(\.viewState.permalink).map { $0 != nil })
             .previewDisplayName("Generic Room")
         
         RoomDetailsScreen(context: simpleRoomViewModel.context)
-            .snapshotPreferences(expect: simpleRoomViewModel.context.observe(\.viewState.permalink).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: simpleRoomViewModel.context.observe(\.viewState.permalink).map { $0 != nil })
             .previewDisplayName("Simple Room")
         
         RoomDetailsScreen(context: dmRoomViewModel.context)
-            .snapshotPreferences(expect: dmRoomViewModel.context.observe(\.viewState.accountOwner).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: dmRoomViewModel.context.observe(\.viewState.accountOwner).map { $0 != nil })
             .previewDisplayName("DM Room")
         
         RoomDetailsScreen(context: dmRoomVerifiedViewModel.context)
-            .snapshotPreferences(expect: dmRoomVerifiedViewModel.context.observe(\.viewState.dmRecipientInfo?.verificationState).map { $0 == .verified }.eraseToStream())
+            .snapshotPreferences(expect: dmRoomVerifiedViewModel.context.observe(\.viewState.dmRecipientInfo?.verificationState).map { $0 == .verified })
             .previewDisplayName("DM Room Verified")
         
         RoomDetailsScreen(context: dmRoomVerificationViolationViewModel.context)
-            .snapshotPreferences(expect: dmRoomVerificationViolationViewModel.context.observe(\.viewState.accountOwner).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: dmRoomVerificationViolationViewModel.context.observe(\.viewState.accountOwner).map { $0 != nil })
             .previewDisplayName("DM Room Verification Violation")
     }
     

ElementX/Sources/Screens/SecureBackup/SecureBackupLogoutConfirmationScreen/View/SecureBackupLogoutConfirmationScreen.swift

@@ -127,26 +127,26 @@ struct SecureBackupLogoutConfirmationScreen_Previews: PreviewProvider, TestableP
             SecureBackupLogoutConfirmationScreen(context: waitingViewModel.context)
         }
         .previewDisplayName("Waiting")
-        .snapshotPreferences(expect: waitingViewModel.context.observe(\.viewState.mode).map { $0 == .waitingToStart(hasStalled: false) }.eraseToStream())
+        .snapshotPreferences(expect: waitingViewModel.context.observe(\.viewState.mode).map { $0 == .waitingToStart(hasStalled: false) })
         
         NavigationStack {
             SecureBackupLogoutConfirmationScreen(context: ongoingViewModel.context)
         }
         .previewDisplayName("Ongoing")
-        .snapshotPreferences(expect: ongoingViewModel.context.observe(\.viewState.mode).map { $0 == .backupOngoing(progress: 0.5) }.eraseToStream())
+        .snapshotPreferences(expect: ongoingViewModel.context.observe(\.viewState.mode).map { $0 == .backupOngoing(progress: 0.5) })
         
         // Uses the same view model as Waiting but with a different expectation.
         NavigationStack {
             SecureBackupLogoutConfirmationScreen(context: waitingViewModel.context)
         }
         .previewDisplayName("Stalled")
-        .snapshotPreferences(expect: waitingViewModel.context.observe(\.viewState.mode).map { $0 == .waitingToStart(hasStalled: true) }.eraseToStream())
+        .snapshotPreferences(expect: waitingViewModel.context.observe(\.viewState.mode).map { $0 == .waitingToStart(hasStalled: true) })
         
         NavigationStack {
             SecureBackupLogoutConfirmationScreen(context: offlineViewModel.context)
         }
         .previewDisplayName("Offline")
-        .snapshotPreferences(expect: offlineViewModel.context.observe(\.viewState.mode).map { $0 == .offline }.eraseToStream())
+        .snapshotPreferences(expect: offlineViewModel.context.observe(\.viewState.mode).map { $0 == .offline })
     }
     
     static func makeViewModel(mode: SecureBackupLogoutConfirmationScreenViewMode) -> SecureBackupLogoutConfirmationScreenViewModel {

ElementX/Sources/Screens/SecureBackup/SecureBackupRecoveryKeyScreen/View/SecureBackupRecoveryKeyScreen.swift

@@ -261,7 +261,7 @@ struct SecureBackupRecoveryKeyScreen_Previews: PreviewProvider, TestablePreview
         NavigationStack {
             SecureBackupRecoveryKeyScreen(context: setupViewModel.context)
         }
-        .snapshotPreferences(expect: setupViewModel.context.observe(\.viewState.recoveryKey).map { $0 != nil }.eraseToStream())
+        .snapshotPreferences(expect: setupViewModel.context.observe(\.viewState.recoveryKey).map { $0 != nil })
         .previewDisplayName("Set up")
         
         NavigationStack {

ElementX/Sources/Screens/SecureBackup/SecureBackupScreen/View/SecureBackupScreen.swift

@@ -129,25 +129,25 @@ struct SecureBackupScreen_Previews: PreviewProvider, TestablePreview {
         NavigationStack {
             SecureBackupScreen(context: bothSetupViewModel.context)
         }
-        .snapshotPreferences(expect: bothSetupViewModel.context.observe(\.viewState.keyBackupState).map { $0 == .enabled }.eraseToStream())
+        .snapshotPreferences(expect: bothSetupViewModel.context.observe(\.viewState.keyBackupState).map { $0 == .enabled })
         .previewDisplayName("Both setup")
         
         NavigationStack {
             SecureBackupScreen(context: onlyKeyBackupSetUpViewModel.context)
         }
-        .snapshotPreferences(expect: onlyKeyBackupSetUpViewModel.context.observe(\.viewState.keyBackupState).map { $0 == .enabled }.eraseToStream())
+        .snapshotPreferences(expect: onlyKeyBackupSetUpViewModel.context.observe(\.viewState.keyBackupState).map { $0 == .enabled })
         .previewDisplayName("Only key backup setup")
         
         NavigationStack {
             SecureBackupScreen(context: keyBackupDisabledViewModel.context)
         }
-        .snapshotPreferences(expect: keyBackupDisabledViewModel.context.observe(\.viewState.keyBackupState).map { $0 == .unknown }.eraseToStream())
+        .snapshotPreferences(expect: keyBackupDisabledViewModel.context.observe(\.viewState.keyBackupState).map { $0 == .unknown })
         .previewDisplayName("Key backup disabled")
         
         NavigationStack {
             SecureBackupScreen(context: recoveryIncompleteViewModel.context)
         }
-        .snapshotPreferences(expect: recoveryIncompleteViewModel.context.observe(\.viewState.recoveryState).map { $0 == .incomplete }.eraseToStream())
+        .snapshotPreferences(expect: recoveryIncompleteViewModel.context.observe(\.viewState.recoveryState).map { $0 == .incomplete })
         .previewDisplayName("Recovery incomplete")
     }
     

ElementX/Sources/Screens/Settings/NotificationSettingsScreen/View/NotificationSettingsScreen.swift

@@ -256,10 +256,10 @@ struct NotificationSettingsScreen_Previews: PreviewProvider, TestablePreview {
 
     static var previews: some View {
         NotificationSettingsScreen(context: viewModel.context)
-            .snapshotPreferences(expect: viewModel.context.observe(\.viewState.settings).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: viewModel.context.observe(\.viewState.settings).map { $0 != nil })
         
         NotificationSettingsScreen(context: viewModelConfigurationMismatch.context)
-            .snapshotPreferences(expect: viewModelConfigurationMismatch.context.observe(\.viewState.settings).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: viewModelConfigurationMismatch.context.observe(\.viewState.settings).map { $0 != nil })
             .previewDisplayName("Configuration mismatch")
     }
 }

ElementX/Sources/Screens/Settings/SettingsScreen/View/SettingsScreen.swift

@@ -262,13 +262,13 @@ struct SettingsScreen_Previews: PreviewProvider, TestablePreview {
         NavigationStack {
             SettingsScreen(context: viewModel.context)
         }
-        .snapshotPreferences(expect: viewModel.context.observe(\.viewState.accountSessionsListURL).map { $0 != nil }.eraseToStream())
+        .snapshotPreferences(expect: viewModel.context.observe(\.viewState.accountSessionsListURL).map { $0 != nil })
         .previewDisplayName("Default")
         
         NavigationStack {
             SettingsScreen(context: bugReportDisabledViewModel.context)
         }
-        .snapshotPreferences(expect: bugReportDisabledViewModel.context.observe(\.viewState.accountSessionsListURL).map { $0 != nil }.eraseToStream())
+        .snapshotPreferences(expect: bugReportDisabledViewModel.context.observe(\.viewState.accountSessionsListURL).map { $0 != nil })
         .previewDisplayName("Bug report disabled")
     }
     

ElementX/Sources/Screens/UserProfileScreen/View/UserProfileScreen.swift

@@ -104,15 +104,15 @@ struct UserProfileScreen_Previews: PreviewProvider, TestablePreview {
     
     static var previews: some View {
         UserProfileScreen(context: verifiedUserViewModel.context)
-            .snapshotPreferences(expect: verifiedUserViewModel.context.observe(\.viewState.isVerified).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: verifiedUserViewModel.context.observe(\.viewState.isVerified).map { $0 != nil })
             .previewDisplayName("Verified User")
         
         UserProfileScreen(context: otherUserViewModel.context)
-            .snapshotPreferences(expect: otherUserViewModel.context.observe(\.viewState.isVerified).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: otherUserViewModel.context.observe(\.viewState.isVerified).map { $0 != nil })
             .previewDisplayName("Other User")
         
         UserProfileScreen(context: accountOwnerViewModel.context)
-            .snapshotPreferences(expect: accountOwnerViewModel.context.observe(\.viewState.isVerified).map { $0 != nil }.eraseToStream())
+            .snapshotPreferences(expect: accountOwnerViewModel.context.observe(\.viewState.isVerified).map { $0 != nil })
             .previewDisplayName("Account Owner")
     }
     

ElementX/Sources/Services/Media/MediaUploadingPreprocessor.swift

@@ -396,7 +396,7 @@ struct MediaUploadingPreprocessor {
     /// - Parameter url: the video URL
     /// - Returns: the URL for the resulting thumbnail and its sizing info as an `ImageProcessingResult`
     private func generateThumbnailForVideoAt(_ url: URL) async throws(MediaUploadingPreprocessorError) -> ImageProcessingInfo {
-        let assetImageGenerator = AVAssetImageGenerator(asset: AVAsset(url: url))
+        let assetImageGenerator = AVAssetImageGenerator(asset: AVURLAsset(url: url))
         assetImageGenerator.appliesPreferredTrackTransform = true
         assetImageGenerator.maximumSize = Constants.maximumThumbnailSize
         

ElementX/Sources/UITests/UITestsSignalling.swift

@@ -94,7 +94,7 @@ enum UITestsSignalling {
                 try rawMessage(.ready).write(to: fileURL, atomically: false, encoding: .utf8)
             case .app:
                 // The app client is started second and checks that there is a ready signal from the tests.
-                guard try String(contentsOf: fileURL) == Message(mode: .tests, signal: .ready).rawValue else { throw UITestsSignalError.testsClientNotReady }
+                guard try String(contentsOf: fileURL, encoding: .utf8) == Message(mode: .tests, signal: .ready).rawValue else { throw UITestsSignalError.testsClientNotReady }
                 isConnected = true
                 // The app client then echoes back to the tests that it is now ready.
                 try send(.ready)