Add current method.

Author: maratal

Example/AblyChatExample/Mocks/MockClients.swift

@@ -563,6 +563,10 @@ class MockOccupancy: Occupancy {
     func get() async throws(ARTErrorInfo) -> OccupancyData {
         OccupancyData(connections: 10, presenceMembers: 5)
     }
+
+    func current() throws(ARTErrorInfo) -> AblyChat.OccupancyData? {
+        OccupancyData(connections: 10, presenceMembers: 5)
+    }
 }
 
 class MockConnection: Connection {

Sources/AblyChat/DefaultOccupancy.swift

@@ -7,6 +7,8 @@ internal final class DefaultOccupancy: Occupancy {
     private let logger: InternalLogger
     private let options: OccupancyOptions
 
+    private var lastOccupancyData: OccupancyData?
+
     internal init(channel: any InternalRealtimeChannelProtocol, chatAPI: ChatAPI, roomName: String, logger: InternalLogger, options: OccupancyOptions) {
         self.channel = channel
         self.chatAPI = chatAPI
@@ -40,6 +42,9 @@ internal final class DefaultOccupancy: Occupancy {
 
             let occupancyData = OccupancyData(connections: connections, presenceMembers: presenceMembers)
             let occupancyEvent = OccupancyEvent(type: .updated, occupancy: occupancyData)
+
+            lastOccupancyData = occupancyData
+
             logger.log(message: "Emitting occupancy event: \(occupancyEvent)", level: .debug)
             callback(occupancyEvent)
         }
@@ -61,4 +66,15 @@ internal final class DefaultOccupancy: Occupancy {
             throw error.toARTErrorInfo()
         }
     }
+
+    // (CHA-O7a) The current method should return the latest occupancy numbers received over the realtime connection in a [meta]occupancy event.
+    internal func current() throws(ARTErrorInfo) -> OccupancyData? {
+        // CHA-O7c
+        if !options.enableEvents {
+            throw ARTErrorInfo(chatError: .occupancyEventsNotEnabled)
+        }
+        // CHA-07a
+        // CHA-07b
+        return lastOccupancyData
+    }
 }

Sources/AblyChat/Errors.swift

@@ -177,6 +177,7 @@ internal enum ChatError {
     case clientIdRequired
     case attachSerialIsNotDefined
     case channelFailedToAttach(cause: ARTErrorInfo?)
+    case occupancyEventsNotEnabled
 
     internal var codeAndStatusCode: ErrorCodeAndStatusCode {
         switch self {
@@ -215,6 +216,8 @@ internal enum ChatError {
             .fixedStatusCode(.badRequest)
         case .channelFailedToAttach:
             .fixedStatusCode(.badRequest)
+        case .occupancyEventsNotEnabled:
+            .fixedStatusCode(.badRequest)
         }
     }
 
@@ -275,6 +278,8 @@ internal enum ChatError {
             "Channel is attached, but attachSerial is not defined."
         case let .channelFailedToAttach(cause):
             "Channel failed to attach: \(String(describing: cause))"
+        case .occupancyEventsNotEnabled:
+            "Cannot perform operation because occupancy events are not enabled for this room."
         }
     }
 
@@ -299,7 +304,8 @@ internal enum ChatError {
              .messageRejectedByBeforePublishRule,
              .messageRejectedByModeration,
              .clientIdRequired,
-             .attachSerialIsNotDefined:
+             .attachSerialIsNotDefined,
+             .occupancyEventsNotEnabled:
             nil
         }
     }

Sources/AblyChat/Occupancy.swift

@@ -27,6 +27,15 @@ public protocol Occupancy: AnyObject, Sendable {
      * - Returns: A current occupancy of the chat room.
      */
     func get() async throws(ARTErrorInfo) -> OccupancyData
+
+    /**
+     * Get the latest occupancy data received from realtime events.
+     *
+     * - Returns: The latest occupancy data, or undefined if no realtime events have been received yet.
+     *
+     * - Throws: ``ARTErrorInfo`` if occupancy events are not enabled for this room.
+     */
+    func current() throws(ARTErrorInfo) -> OccupancyData?
 }
 
 /// `AsyncSequence` variant of receiving room occupancy events.

Tests/AblyChatTests/DefaultRoomOccupancyTests.swift

@@ -5,8 +5,9 @@ import Testing
 @MainActor
 struct DefaultRoomOccupancyTests {
     // @spec CHA-O3
+    // @spec CHA-O7b
     @Test
-    func requestOccupancyCheck() async throws {
+    func occupancyGet() async throws {
         // Given
         let realtime = MockRealtime {
             MockHTTPPaginatedResponse(
@@ -25,7 +26,7 @@ struct DefaultRoomOccupancyTests {
             chatAPI: chatAPI,
             roomName: "basketball",
             logger: TestLogger(),
-            options: .init()
+            options: .init(enableEvents: true)
         )
 
         // When
@@ -34,18 +35,38 @@ struct DefaultRoomOccupancyTests {
         // Then
         #expect(occupancyInfo.connections == 5)
         #expect(occupancyInfo.presenceMembers == 2)
+
+        let currentOccupancy = try defaultOccupancy.current()
+        #expect(currentOccupancy == nil)
     }
 
     // @specUntested CHA-O4e - We chose to implement this failure with an idiomatic fatalError instead of throwing, but we can’t test this.
 
     // @spec CHA-O4a
     // @spec CHA-O4c
+    // @spec CHA-O7a
     @Test
     func usersCanSubscribeToRealtimeOccupancyUpdates() async throws {
         // Given
         let realtime = MockRealtime()
         let chatAPI = ChatAPI(realtime: realtime)
-        let channel = MockRealtimeChannel(name: "basketball::$chat")
+        let channel = MockRealtimeChannel(
+            name: "basketball::$chat",
+            messageToEmitOnSubscribe: {
+                let message = ARTMessage()
+                message.action = .create // arbitrary
+                message.serial = "" // arbitrary
+                message.clientId = "" // arbitrary
+                message.data = [
+                    "metrics": [
+                        "connections": 5, // arbitrary
+                        "presenceMembers": 2, // arbitrary
+                    ],
+                ]
+                message.version = "0" // arbitrary
+                return message
+            }()
+        )
         let defaultOccupancy = DefaultOccupancy(
             channel: channel,
             chatAPI: chatAPI,
@@ -54,17 +75,19 @@ struct DefaultRoomOccupancyTests {
             options: .init(enableEvents: true)
         )
 
-        // CHA-O4a, CHA-O4c
+        // CHA-O4a, CHA-O4c, CHA-O7a
 
         // When
         let subscription = defaultOccupancy.subscribe()
-        let occupancyData = OccupancyData(connections: 5, presenceMembers: 2)
-        subscription.emit(OccupancyEvent(type: .updated, occupancy: occupancyData))
 
         // Then
         let occupancyEvent = try #require(await subscription.first { @Sendable _ in true })
         #expect(occupancyEvent.occupancy.connections == 5)
         #expect(occupancyEvent.occupancy.presenceMembers == 2)
+
+        let currentOccupancy = try defaultOccupancy.current()
+        #expect(currentOccupancy?.connections == 5)
+        #expect(currentOccupancy?.presenceMembers == 2)
     }
 
     // @spec CHA-O4g
@@ -98,4 +121,32 @@ struct DefaultRoomOccupancyTests {
         #expect(occupancyEvent.occupancy.connections == 0)
         #expect(occupancyEvent.occupancy.presenceMembers == 0)
     }
+
+    // @spec CHA-O7c
+    @Test
+    func occupancyCurrentThrowsError() async throws {
+        // Given
+        let realtime = MockRealtime()
+        let chatAPI = ChatAPI(realtime: realtime)
+        let channel = MockRealtimeChannel(name: "basketball::$chat")
+        let defaultOccupancy = DefaultOccupancy(
+            channel: channel,
+            chatAPI: chatAPI,
+            roomName: "basketball",
+            logger: TestLogger(),
+            // Wnen
+            options: .init() // enableEvents: false
+        )
+
+        // Then
+        // TODO: avoids compiler crash (https://github.com/ably/ably-chat-swift/issues/233), revert once Xcode 16.3 released
+        let doIt = {
+            _ = try defaultOccupancy.current()
+        }
+        await #expect {
+            try await doIt()
+        } throws: { error in
+            error as? ARTErrorInfo == ARTErrorInfo(chatError: .occupancyEventsNotEnabled)
+        }
+    }
 }