Use files instead of UDP for signalling. (#585)

.swiftlint.yml

@@ -40,6 +40,10 @@ function_body_length:
   warning: 50
   error: 100
 
+nesting:
+  type_level:
+    warning: 5
+
 custom_rules:
   print_deprecation:
     regex: "\\b(print)\\b"

ElementX.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -72,13 +72,22 @@
         "version" : "7.4.1"
       }
     },
+    {
+      "identity" : "kzfilewatchers",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/krzysztofzablocki/KZFileWatchers",
+      "state" : {
+        "branch" : "master",
+        "revision" : "d27a9557427d261adccdf4b566acc9d9c0fec6f4"
+      }
+    },
     {
       "identity" : "matrix-analytics-events",
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/matrix-org/matrix-analytics-events",
       "state" : {
-        "branch" : "main",
+        "revision" : "94598bd8ef3aa2a3d3848c656c37d5e95b6b1cff",
-        "revision" : "4bcc7f566b165cd2d8fde07d23bda77e1d9fbb2d"
+        "version" : "0.4.0"
       }
     },
     {

ElementX/Sources/Services/Timeline/TimelineController/MockRoomTimelineController.swift

@@ -32,12 +32,15 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
     
     var timelineItems: [RoomTimelineItemProtocol] = RoomTimelineItemFixtures.default
     
-    private var connection: UITestsSignalling.Connection?
+    private var client: UITestsSignalling.Client?
     
     init(listenForSignals: Bool = false) {
-        if listenForSignals {
+        guard listenForSignals else { return }
-            connection = .init()
+        
-            Task { try await startListening() }
+        do {
+            try startListening()
+        } catch {
+            fatalError("Failure setting up signalling: \(error)")
         }
     }
     
@@ -70,20 +73,18 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
     
     // MARK: - UI Test signalling
     
+    /// The cancellable used for UI Tests signalling.
+    private var signalCancellable: AnyCancellable?
+    
     /// Allows the simulation of server responses by listening for signals from UI tests.
-    private func startListening() async throws {
+    private func startListening() throws {
-        try await connection?.connect()
+        let client = try UITestsSignalling.Client(mode: .app)
         
-        Task {
+        signalCancellable = client.signals.sink { [weak self] signal in
-            while let connection {
+            Task { try await self?.handleSignal(signal) }
-                do {
-                    try await handleSignal(connection.receive())
-                } catch {
-                    connection.disconnect()
-                    self.connection = nil
-                }
-            }
         }
+        
+        self.client = client
     }
     
     /// Handles a UI test signal as necessary.
@@ -106,7 +107,7 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
         timelineItems.append(incomingItem)
         callbacks.send(.updatedTimelineItems)
         
-        try? await connection?.send(.success)
+        try client?.send(.success)
     }
     
     /// Prepends the next chunk of items to the `timelineItems` array.
@@ -119,6 +120,6 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
         callbacks.send(.updatedTimelineItems)
         callbacks.send(.isBackPaginating(false))
         
-        try? await connection?.send(.success)
+        try client?.send(.success)
     }
 }

ElementX/Sources/UITests/UITestsSignalling.swift

@@ -14,12 +14,13 @@
 // limitations under the License.
 //
 
-import Network
+import Combine
+import KZFileWatchers
 import SwiftUI
 
 enum UITestsSignal: String {
-    /// An internal signal used to bring up the connection.
+    /// An internal signal used to indicate that one side of the connection is ready.
-    case connect
+    case ready
     /// Ask the app to back paginate.
     case paginate
     /// Ask the app to simulate an incoming message.
@@ -28,211 +29,127 @@ enum UITestsSignal: String {
     case success
 }
 
-enum UITestsSignalError: Error {
+enum UITestsSignalError: String, LocalizedError {
-    /// An unknown error occurred.
+    /// The app client failed to start as the tests client isn't ready.
-    case unknown
+    case testsClientNotReady
-    /// Signalling could not be used as is hasn't been enabled.
+    /// Failed to send a signal as a connection hasn't been established.
-    case disabled
-    /// The connection was cancelled.
-    case cancelled
-    /// The connection hasn't been established.
     case notConnected
-    /// Attempted to receive multiple signals at once.
+    
-    case awaitingAnotherSignal
+    var errorDescription: String? { "UITestsSignalError.\(rawValue)" }
-    /// Receiving the next signal timed out.
-    case timeout
-    /// A network error occurred.
-    case nwError(NWError)
-    /// An unexpected signal was received. This error isn't used internally.
-    case unexpected
 }
 
 enum UITestsSignalling {
-    /// The Bonjour service name used for the connection. The device name
+    /// A two-way file-based signalling client that can be used to signal between the app and the UI tests runner.
-    /// is included to allow UI tests to run on multiple devices simultaneously.
-    private static let serviceName = "UITestsSignalling \(UIDevice.current.name) (\(Locale.current.identifier))"
-    /// The Bonjour service type used for the connection.
-    private static let serviceType = "_signalling._udp."
-    /// The Bonjour domain used for the connection.
-    private static let domain = "local."
-    /// The DispatchQueue used for networking.
-    private static let queue: DispatchQueue = .main
-    
-    /// A network listener that can be used in the UI tests runner to create a two-way `Connection` with the app.
-    class Listener {
-        /// The underlying network listener.
-        private let listener: NWListener
-        
-        /// The established connection. This is stored in case the connection is established
-        /// before `connection()` is awaited and so the continuation is still `nil`.
-        private var establishedConnection: Connection?
-        /// The continuation to call when a connection is established.
-        private var connectionContinuation: CheckedContinuation<Connection, Error>?
-        
-        /// Creates a new signalling `Listener` and starts listening.
-        init() throws {
-            let service = NWListener.Service(name: UITestsSignalling.serviceName, type: UITestsSignalling.serviceType, domain: UITestsSignalling.domain)
-            listener = try NWListener(service: service, using: .udp)
-            listener.newConnectionHandler = { [weak self] nwConnection in
-                let connection = Connection(nwConnection: nwConnection)
-                nwConnection.start(queue: UITestsSignalling.queue)
-                nwConnection.stateUpdateHandler = { state in
-                    switch state {
-                    case .ready:
-                        connection.receiveNextMessage()
-                        self?.establishedConnection = connection
-                        self?.connectionContinuation?.resume(returning: connection)
-                    case .failed(let error):
-                        self?.connectionContinuation?.resume(with: .failure(error))
-                    default:
-                        break
-                    }
-                }
-                self?.listener.cancel() // Stop listening for connections when one is discovered.
-            }
-            listener.start(queue: UITestsSignalling.queue)
-        }
-        
-        /// Returns the negotiated `Connection` as and when it has been established.
-        func connection() async throws -> Connection {
-            guard listener.state == .setup else { throw UITestsSignalError.unknown }
-            if let establishedConnection {
-                return establishedConnection
-            }
-            return try await withCheckedThrowingContinuation { [weak self] continuation in
-                self?.connectionContinuation = continuation
-            }
-        }
-        
-        /// Stops the listening when a connection hasn't been established.
-        func cancel() {
-            listener.cancel()
-            if let connectionContinuation {
-                connectionContinuation.resume(throwing: UITestsSignalError.cancelled)
-                self.connectionContinuation = nil
-            }
-        }
-    }
-
-    /// A two-way UDP connection that can be used for signalling between the app and the UI tests runner.
     /// The connection should be created as follows:
-    /// - Create a `Listener` in the UI tests before launching the app. This will automatically start listening for a connection.
+    /// - Create a `Client` in `tests` mode in your UI tests before launching the app. It will start listening for signals.
-    /// - With in the App, create a `Connection` and call `connect()` to establish a connection.
+    /// - Within the app, create a `Client` in `app` mode. This will check that the tests are ready and echo back that the app is too.
-    /// - Await the `connection()` on the `Listener` when you need to send the signal.
+    /// - Call `waitForApp()` in the tests when you need to send the signal. This will suspend execution until the app has signalled it is ready.
-    /// - The two `Connection` objects can now be used for two-way signalling.
+    /// - The two `Client` objects can now be used for two-way signalling.
-    class Connection {
+    class Client {
-        /// The underlying network connection.
+        /// The file watcher responsible for receiving signals.
-        private let connection: NWConnection
+        private let fileWatcher: FileWatcher.Local
-        /// A continuation to call each time a signal is received.
-        private var nextMessageContinuation: CheckedContinuation<UITestsSignal, Error>?
-        /// A task to handle the timeout when receiving a signal.
-        private var nextMessageTimeoutTask: Task<Void, Never>? {
-            didSet {
-                oldValue?.cancel()
-            }
-        }
         
-        /// Creates a new signalling `Connection`.
+        /// The file name used for the connection.
-        init() {
+        ///
-            let endpoint = NWEndpoint.service(name: UITestsSignalling.serviceName,
+        /// The device name is included to allow UI tests to run on multiple devices simultaneously.
-                                              type: UITestsSignalling.serviceType,
+        /// When using parallel execution, each execution will spawn a simulator clone with its own unique name.
-                                              domain: UITestsSignalling.domain,
+        private let fileURL = {
-                                              interface: nil)
+            let directory = URL(filePath: "/Users/Shared")
-            connection = NWConnection(to: endpoint, using: .udp)
+            let deviceName = (UIDevice.current.name).replacing(" ", with: "-")
-        }
+            return directory.appending(component: "UITestsSignalling-\(deviceName)")
+        }()
         
-        /// Creates a new signalling `Connection` from an established `NWConnection`.
+        /// A mode that defines the behaviour of the client.
-        fileprivate init(nwConnection: NWConnection) {
+        enum Mode: String { case app, tests }
-            connection = nwConnection
+        /// The mode that the client is using.
-        }
+        let mode: Mode
         
-        /// Attempts to establish a connection with a `Listener`.
+        /// A publisher the will be sent every time a new signal is received.
-        func connect() async throws {
+        let signals = PassthroughSubject<UITestsSignal, Never>()
-            guard connection.state == .setup else { return }
+        
+        /// Whether or not the client has established a connection.
+        private(set) var isConnected = false
+        
+        /// Creates a new signalling `Client`.
+        init(mode: Mode) throws {
+            fileWatcher = .init(path: fileURL.path())
+            self.mode = mode
             
-            return try await withCheckedThrowingContinuation { continuation in
+            switch mode {
-                connection.start(queue: UITestsSignalling.queue)
+            case .tests:
-                connection.stateUpdateHandler = { state in
+                // The tests client is started first and writes to the file saying it is ready.
-                    switch state {
+                try rawSignal(.ready).write(to: fileURL, atomically: false, encoding: .utf8)
-                    case .ready:
+            case .app:
-                        self.receiveNextMessage()
+                // The app client is started second and checks that there is a ready signal from the tests.
-                        continuation.resume()
+                guard try String(contentsOf: fileURL) == "\(Mode.tests):\(UITestsSignal.ready)" else { throw UITestsSignalError.testsClientNotReady }
-                        Task { try await self.send(.connect) }
+                isConnected = true
-                    case .failed(let error):
+                // The app client then echoes back to the tests that it is now ready.
-                        continuation.resume(with: .failure(error))
+                try send(.ready)
-                    default:
-                        break
-                    }
-                }
             }
-        }
-        
-        /// Stops the connection.
-        func disconnect() {
-            connection.cancel()
-            if let nextMessageContinuation {
-                nextMessageContinuation.resume(throwing: UITestsSignalError.cancelled)
-                self.nextMessageContinuation = nil
-                nextMessageTimeoutTask = nil
-            }
-        }
-        
-        /// Sends a message to the other side of the connection.
-        func send(_ signal: UITestsSignal) async throws {
-            guard connection.state == .ready else { throw UITestsSignalError.notConnected }
-            let data = signal.rawValue.data(using: .utf8)
-            connection.send(content: data, completion: .idempotent)
-        }
-        
-        /// Returns the next message received from the other side of the connection.
-        func receive() async throws -> UITestsSignal {
-            guard connection.state == .ready else { throw UITestsSignalError.notConnected }
-            guard nextMessageContinuation == nil else { throw UITestsSignalError.awaitingAnotherSignal }
             
-            return try await withCheckedThrowingContinuation { continuation in
+            try fileWatcher.start { [weak self] result in
-                self.nextMessageContinuation = continuation
+                self?.handleFileRefresh(result)
-                
-                // Add a 30 second timeout to stop tests from hanging
-                self.nextMessageTimeoutTask = Task { [weak self] in
-                    guard let self else { return }
-                    try? await Task.sleep(for: .seconds(30))
-                    
-                    guard !Task.isCancelled,
-                          let nextMessageContinuation = self.nextMessageContinuation
-                    else { return }
-                    
-                    nextMessageContinuation.resume(throwing: UITestsSignalError.timeout)
-                    self.nextMessageContinuation = nil
-                    self.nextMessageTimeoutTask = nil
-                }
             }
         }
         
-        /// Processes the next message received by the connection.
+        /// Suspends execution until the app's Client has signalled that it's ready.
-        fileprivate func receiveNextMessage() {
+        func waitForApp() async {
-            connection.receiveMessage { [weak self] completeContent, _, isComplete, error in
+            guard mode == .tests else { fatalError("The app can't wait for itself.") }
-                guard let self else { return }
+            
-                guard isComplete else { fatalError("Partial messages not supported") }
+            guard !isConnected else { return }
-                
+            await _ = signals.values.first { $0 == .ready }
-                guard let completeContent,
+            NSLog("UITestsSignalling: Connected to app.")
-                      let message = String(data: completeContent, encoding: .utf8),
+        }
-                      let signal = UITestsSignal(rawValue: message)
+
-                else {
+        /// Stops listening for signals.
-                    let error: UITestsSignalError = error.map { .nwError($0) } ?? .unknown
+        func stop() throws {
-                    self.nextMessageContinuation?.resume(with: .failure(error))
+            try fileWatcher.stop()
-                    self.nextMessageContinuation = nil
+        }
-                    self.nextMessageTimeoutTask = nil
+
-                    return
+        /// Sends a signal.
-                }
+        func send(_ signal: UITestsSignal) throws {
-                
+            guard isConnected else { throw UITestsSignalError.notConnected }
-                if signal != .connect {
+            
-                    self.nextMessageContinuation?.resume(returning: signal)
+            let rawSignal = rawSignal(signal)
-                    self.nextMessageContinuation = nil
+            try rawSignal.write(to: fileURL, atomically: false, encoding: .utf8)
-                    self.nextMessageTimeoutTask = nil
+            NSLog("UITestsSignalling: Sent \(rawSignal)")
-                }
+        }
-                
+        
-                self.receiveNextMessage()
+        /// The signal formatted as a string, prefixed with an identifier for the sender.
+        /// E.g. The tests client would produce `tests:ready` for the ready signal.
+        private func rawSignal(_ signal: UITestsSignal) -> String {
+            "\(mode.rawValue):\(signal.rawValue)"
+        }
+        
+        /// Handles a file refresh to receive a new signal.
+        fileprivate func handleFileRefresh(_ result: FileWatcher.RefreshResult) {
+            switch result {
+            case .noChanges:
+                guard let data = try? Data(contentsOf: fileURL) else { return }
+                processFileData(data)
+            case .updated(let data):
+                processFileData(data)
             }
         }
+        
+        /// Processes string data from the file and publishes its signal.
+        private func processFileData(_ data: Data) {
+            guard let message = String(data: data, encoding: .utf8) else { return }
+            
+            let components = message.components(separatedBy: ":")
+            
+            guard components.count == 2,
+                  components[0] != mode.rawValue, // Filter out messages sent by this client.
+                  let signal = UITestsSignal(rawValue: components[1])
+            else { return }
+            
+            if signal == .ready {
+                isConnected = true
+            }
+            
+            signals.send(signal)
+            
+            NSLog("UITestsSignalling: Received \(message)")
+        }
     }
 }

ElementX/SupportingFiles/target.yml

@@ -120,6 +120,7 @@ targets:
     - package: DTCoreText
     - package: KeychainAccess
     - package: Kingfisher
+    - package: KZFileWatchers
     - package: PostHog
     - package: SwiftyBeaver
     - package: SwiftState

UITests/Sources/RoomScreenUITests.swift

@@ -19,8 +19,6 @@ import XCTest
 
 @MainActor
 class RoomScreenUITests: XCTestCase {
-    let connectionWaitDuration: Duration = .seconds(2)
-    
     func testPlainNoAvatar() {
         let app = Application.launch(.roomPlainNoAvatar)
 
@@ -46,47 +44,44 @@ class RoomScreenUITests: XCTestCase {
         app.assertScreenshot(.roomSmallTimeline)
     }
     
-    func disabled_testSmallTimelineWithIncomingAndPagination() async throws {
+    func testSmallTimelineWithIncomingAndPagination() async throws {
-        let listener = try UITestsSignalling.Listener()
+        let client = try UITestsSignalling.Client(mode: .tests)
         
         let app = Application.launch(.roomSmallTimelineIncomingAndSmallPagination)
         
-        let connection = try await listener.connection()
+        await client.waitForApp()
-        try await Task.sleep(for: connectionWaitDuration) // Allow the connection to settle on CI/Intel...
+        defer { try? client.stop() }
-        defer { connection.disconnect() }
         
         // When a back pagination occurs and an incoming message arrives.
-        try await performOperation(.incomingMessage, using: connection)
+        try await performOperation(.incomingMessage, using: client)
-        try await performOperation(.paginate, using: connection)
+        try await performOperation(.paginate, using: client)
 
         // Then the 4 visible messages should stay aligned to the bottom.
         app.assertScreenshot(.roomSmallTimelineIncomingAndSmallPagination)
     }
     
-    func disabled_testSmallTimelineWithLargePagination() async throws {
+    func testSmallTimelineWithLargePagination() async throws {
-        let listener = try UITestsSignalling.Listener()
+        let client = try UITestsSignalling.Client(mode: .tests)
         
         let app = Application.launch(.roomSmallTimelineLargePagination)
         
-        let connection = try await listener.connection()
+        await client.waitForApp()
-        try await Task.sleep(for: connectionWaitDuration) // Allow the connection to settle on CI/Intel...
+        defer { try? client.stop() }
-        defer { connection.disconnect() }
         
         // When a large back pagination occurs.
-        try await performOperation(.paginate, using: connection)
+        try await performOperation(.paginate, using: client)
 
         // The bottom of the timeline should remain visible with more items added above.
         app.assertScreenshot(.roomSmallTimelineLargePagination)
     }
     
-    func disabled_testTimelineLayoutInMiddle() async throws {
+    func testTimelineLayoutInMiddle() async throws {
-        let listener = try UITestsSignalling.Listener()
+        let client = try UITestsSignalling.Client(mode: .tests)
         
         let app = Application.launch(.roomLayoutMiddle)
         
-        let connection = try await listener.connection()
+        await client.waitForApp()
-        try await Task.sleep(for: connectionWaitDuration) // Allow the connection to settle on CI/Intel...
+        defer { try? client.stop() }
-        defer { connection.disconnect() }
         
         // Given a timeline that is neither at the top nor the bottom.
         app.tables.element.swipeDown()
@@ -94,13 +89,13 @@ class RoomScreenUITests: XCTestCase {
         app.assertScreenshot(.roomLayoutMiddle, step: 0) // Assert initial state for comparison.
         
         // When a back pagination occurs.
-        try await performOperation(.paginate, using: connection)
+        try await performOperation(.paginate, using: client)
         
         // Then the UI should remain unchanged.
         app.assertScreenshot(.roomLayoutMiddle, step: 0)
         
         // When an incoming message arrives
-        try await performOperation(.incomingMessage, using: connection)
+        try await performOperation(.incomingMessage, using: client)
         
         // Then the UI should still remain unchanged.
         app.assertScreenshot(.roomLayoutMiddle, step: 0)
@@ -112,14 +107,13 @@ class RoomScreenUITests: XCTestCase {
         app.assertScreenshot(.roomLayoutMiddle, step: 1)
     }
     
-    func disabled_testTimelineLayoutAtTop() async throws {
+    func testTimelineLayoutAtTop() async throws {
-        let listener = try UITestsSignalling.Listener()
+        let client = try UITestsSignalling.Client(mode: .tests)
         
         let app = Application.launch(.roomLayoutTop)
         
-        let connection = try await listener.connection()
+        await client.waitForApp()
-        try await Task.sleep(for: connectionWaitDuration) // Allow the connection to settle on CI/Intel...
+        defer { try? client.stop() }
-        defer { connection.disconnect() }
         
         // Given a timeline that is scrolled to the top.
         while !app.staticTexts["Bacon ipsum dolor amet commodo incididunt ribeye dolore cupidatat short ribs."].isHittable {
@@ -129,23 +123,22 @@ class RoomScreenUITests: XCTestCase {
         app.assertScreenshot(.roomLayoutTop, insets: cropped) // Assert initial state for comparison.
         
         // When a back pagination occurs.
-        try await performOperation(.paginate, using: connection)
+        try await performOperation(.paginate, using: client)
 
         // Then the bottom of the timeline should remain unchanged (with new items having been added above).
         app.assertScreenshot(.roomLayoutTop, insets: cropped)
     }
     
-    func disabled_testTimelineLayoutAtBottom() async throws {
+    func testTimelineLayoutAtBottom() async throws {
-        let listener = try UITestsSignalling.Listener()
+        let client = try UITestsSignalling.Client(mode: .tests)
         
         let app = Application.launch(.roomLayoutBottom)
         
-        let connection = try await listener.connection()
+        await client.waitForApp()
-        try await Task.sleep(for: connectionWaitDuration) // Allow the connection to settle on CI/Intel...
+        defer { try? client.stop() }
-        defer { connection.disconnect() }
         
         // When an incoming message arrives.
-        try await performOperation(.incomingMessage, using: connection)
+        try await performOperation(.incomingMessage, using: client)
         
         // Then the timeline should scroll down to reveal the message.
         app.assertScreenshot(.roomLayoutBottom, step: 0)
@@ -159,10 +152,10 @@ class RoomScreenUITests: XCTestCase {
     
     // MARK: - Helper Methods
     
-    private func performOperation(_ operation: UITestsSignal, using connection: UITestsSignalling.Connection) async throws {
+    private func performOperation(_ operation: UITestsSignal, using client: UITestsSignalling.Client) async throws {
-        try await connection.send(operation)
+        try client.send(operation)
-        guard try await connection.receive() == .success else { throw UITestsSignalError.unexpected }
+        await _ = client.signals.values.first { $0 == .success }
-        try await Task.sleep(for: connectionWaitDuration) // Allow the timeline to update, and the connection to be ready
+        try await Task.sleep(for: .milliseconds(500)) // Allow the timeline to update
     }
     
     private func tapMessageComposer(in app: XCUIApplication) async throws {

UITests/SupportingFiles/target.yml

@@ -34,6 +34,7 @@ targets:
     - package: DTCoreText
     - package: KeychainAccess
     - package: Kingfisher
+    - package: KZFileWatchers
     - package: PostHog
     - package: SwiftyBeaver
     - package: SwiftState

changelog.d/534.bugfix

@@ -1 +1 @@
-Fix UI Tests for OnboardingScreen, BugReportScreen, ServerSelectionScreen, and UserSessionFlows.
+Fix UI Tests for OnboardingScreen, BugReportScreen, ServerSelectionScreen, and UserSessionFlows. Fix UITestsSignalling by switching to file-based communication with a publisher.

project.yml

@@ -46,7 +46,7 @@ packages:
     path: DesignKit
   AnalyticsEvents:
     url: https://github.com/matrix-org/matrix-analytics-events
-    branch: main
+    exactVersion: 0.4.0
   AppAuth:
     url: https://github.com/openid/AppAuth-iOS
     majorVersion: 1.5.0
@@ -65,6 +65,9 @@ packages:
   Kingfisher:
     url: https://github.com/onevcat/Kingfisher
     majorVersion: 7.2.0
+  KZFileWatchers:
+    url: https://github.com/krzysztofzablocki/KZFileWatchers
+    branch: master
   Introspect:
     url: https://github.com/siteline/SwiftUI-Introspect
     majorVersion: 0.1.4