Implement Messages.get() according to CHA-M13

Author: maratal

Example/AblyChatExample/Mocks/MockClients.swift

@@ -219,6 +219,23 @@ class MockMessages: Messages {
         mockSubscriptions.emit(ChatMessageEvent(message: message))
         return message
     }
+
+    func get(withSerial serial: String) async throws(ARTErrorInfo) -> Message {
+        Message(
+            serial: serial,
+            action: .messageCreate,
+            clientID: clientID,
+            text: MockStrings.randomPhrase(),
+            metadata: [:],
+            headers: [:],
+            version: .init(
+                serial: serial,
+                timestamp: Date(),
+            ),
+            timestamp: Date(),
+            reactions: .init(unique: [:], distinct: [:], multiple: [:]),
+        )
+    }
 }
 
 class MockMessageReactions: MessageReactions {

Sources/AblyChat/ChatAPI.swift

@@ -33,6 +33,12 @@ internal final class ChatAPI {
         return try await makePaginatedRequest(endpoint, params: params.asQueryItems())
     }
 
+    // (CHA-M13) Get a single message by its serial
+    internal func getMessage(roomName: String, serial: String) async throws(InternalError) -> Message {
+        let endpoint = messageUrl(roomName: roomName, serial: serial)
+        return try await makeRequest(endpoint, method: "GET")
+    }
+
     internal struct SendMessageReactionParams: Sendable {
         internal let type: MessageReactionType
         internal let name: String

Sources/AblyChat/DefaultMessages.swift

@@ -147,6 +147,15 @@ internal final class DefaultMessages: Messages {
         }
     }
 
+    // (CHA-M13) A single message must be retrievable from the REST API.
+    internal func get(withSerial serial: String) async throws(ARTErrorInfo) -> Message {
+        do {
+            return try await chatAPI.getMessage(roomName: roomName, serial: serial)
+        } catch {
+            throw error.toARTErrorInfo()
+        }
+    }
+
     private func resolveSubscriptionStart() async throws(InternalError) -> String {
         logger.log(message: "Resolving subscription start serial", level: .debug)
         // (CHA-M5a) If a subscription is added when the underlying realtime channel is ATTACHED, then the subscription point is the current channelSerial of the realtime channel.

Sources/AblyChat/Messages.swift

@@ -79,6 +79,16 @@ public protocol Messages: AnyObject, Sendable {
      */
     func delete(message: Message, details: OperationDetails?) async throws(ARTErrorInfo) -> Message
 
+    /**
+     * Get a message by its serial.
+     *
+     * - Parameters:
+     *   - serial: The serial of the message to get.
+     *
+     * - Returns: The message with the specified serial.
+     */
+    func get(withSerial serial: String) async throws(ARTErrorInfo) -> Message
+
     /**
      * Add, delete, and subscribe to message reactions.
      */

Tests/AblyChatTests/ChatAPITests.swift

@@ -143,24 +143,24 @@ struct ChatAPITests {
             paginatedResponse: paginatedResponse,
             items: [
                 Message(
-                    serial: "3446456",
+                    serial: "123456789-000@123456789:000",
                     action: .messageCreate,
                     clientID: "random",
                     text: "hello",
                     metadata: [:],
                     headers: [:],
-                    version: .init(serial: "3446456", timestamp: Date(timeIntervalSince1970: 1_730_943_049.269)), // from successGetMessagesWithItems
+                    version: .init(serial: "123456789-000@123456789:000", timestamp: Date(timeIntervalSince1970: 1_730_943_049.269)), // from successGetMessagesWithItems
                     timestamp: Date(timeIntervalSince1970: 1_730_943_049.269),
                     reactions: .empty,
                 ),
                 Message(
-                    serial: "3446457",
+                    serial: "123456789-000@123456789:001",
                     action: .messageCreate,
                     clientID: "random",
                     text: "hello response",
                     metadata: [:],
                     headers: [:],
-                    version: .init(serial: "3446457", timestamp: Date(timeIntervalSince1970: 1_730_943_051.269)),
+                    version: .init(serial: "123456789-000@123456789:001", timestamp: Date(timeIntervalSince1970: 1_730_943_051.269)),
                     timestamp: Date(timeIntervalSince1970: 1_730_943_051.269),
                     reactions: .empty,
                 ),

Tests/AblyChatTests/DefaultMessagesTests.swift

@@ -241,6 +241,77 @@ struct DefaultMessagesTests {
         }
     }
 
+    // @spec CHA-M13a
+    @Test
+    func getMessage() async throws {
+        // Given
+        let realtime = MockRealtime {
+            MockHTTPPaginatedResponse(
+                items: [
+                    [
+                        "serial": "123456789-000@123456789:000",
+                        "version": [
+                            "serial": "123456789-000@123456789:000",
+                            "timestamp": 1_631_840_000_000,
+                        ],
+                        "metadata": ["key1": "val1"],
+                        "headers": ["key2": "val2"],
+                        "timestamp": 1_631_840_000_000,
+                        "text": "hey",
+                        "clientId": "clientId",
+                        "action": "message.create",
+                    ],
+                ],
+                statusCode: 200,
+                headers: [:],
+            )
+        }
+        let chatAPI = ChatAPI(realtime: realtime)
+        let channel = MockRealtimeChannel(initialState: .attached)
+        let defaultMessages = DefaultMessages(channel: channel, chatAPI: chatAPI, roomName: "basketball", logger: TestLogger())
+
+        // When
+        let retrievedMessage = try await defaultMessages.get(withSerial: "123456789-000@123456789:000")
+
+        // Then
+        #expect(retrievedMessage.serial == "123456789-000@123456789:000")
+        #expect(retrievedMessage.action == .messageCreate)
+        #expect(retrievedMessage.text == "hey")
+        #expect(retrievedMessage.clientID == "clientId")
+        #expect(retrievedMessage.version.serial == "123456789-000@123456789:000")
+        #expect(retrievedMessage.version.timestamp == Date(timeIntervalSince1970: 1_631_840_000_000 / 1000))
+        #expect(retrievedMessage.metadata == ["key1": "val1"])
+        #expect(retrievedMessage.headers == ["key2": "val2"])
+        #expect(retrievedMessage.timestamp == Date(timeIntervalSince1970: 1_631_840_000_000 / 1000))
+        #expect(realtime.callRecorder.hasRecord(
+            matching: "request(_:path:params:body:headers:)",
+            arguments: ["method": "GET", "path": "/chat/v4/rooms/basketball/messages/123456789-000@123456789:000", "body": [:], "params": [:], "headers": [:]],
+        ))
+    }
+
+    // @spec CHA-M13b
+    @Test
+    func errorShouldBeThrownIfErrorIsReturnedFromGetRESTChatAPI() async throws {
+        // Given
+        let realtime = MockRealtime { @Sendable () throws(ARTErrorInfo) in
+            throw ARTErrorInfo(domain: "SomeDomain", code: 123)
+        }
+        let chatAPI = ChatAPI(realtime: realtime)
+        let channel = MockRealtimeChannel()
+        let defaultMessages = DefaultMessages(channel: channel, chatAPI: chatAPI, roomName: "basketball", logger: TestLogger())
+
+        // Then
+        // TODO: avoids compiler crash (https://github.com/ably/ably-chat-swift/issues/233), revert once Xcode 16.3 released
+        let doIt = {
+            _ = try await defaultMessages.get(withSerial: "123456789-000@123456789:000")
+        }
+        await #expect {
+            try await doIt()
+        } throws: { error in
+            error as? ARTErrorInfo == ARTErrorInfo(domain: "SomeDomain", code: 123)
+        }
+    }
+
     // @spec CHA-M5a
     // @specOneOf(4/6) CHA-RST6 - Escaping room name for API get messages
     @Test

Tests/AblyChatTests/IntegrationTests.swift

@@ -262,6 +262,14 @@ struct IntegrationTests {
             #expect(value.clientIDs == [messageToReact.clientID])
         }
 
+        // (8) Get a single message by its serial
+        let retrievedMessage = try await rxRoom.messages.get(withSerial: rxMessageFromHistory.serial)
+        #expect(retrievedMessage.serial == rxMessageFromHistory.serial)
+        #expect(retrievedMessage.text == rxMessageFromHistory.text)
+        #expect(retrievedMessage.clientID == rxMessageFromHistory.clientID)
+        // Verify the retrieved message has the same reaction summary
+        #expect(retrievedMessage.reactions.distinct.count == rxMessageFromHistory.reactions.distinct.count)
+
         // MARK: - Editing and Deleting Messages
 
         // Reuse message subscription and message from (5) and (6) above

Tests/AblyChatTests/Mocks/MockHTTPPaginatedResponse.swift

@@ -101,25 +101,25 @@ extension MockHTTPPaginatedResponse {
         items: [
             [
                 "clientId": "random",
-                "serial": "3446456",
+                "serial": "123456789-000@123456789:000",
                 "action": "message.create",
                 "text": "hello",
                 "metadata": [:],
                 "headers": [:],
                 "version": [
-                    "serial": "3446456",
+                    "serial": "123456789-000@123456789:000",
                 ],
                 "timestamp": 1_730_943_049_269,
             ],
             [
                 "clientId": "random",
-                "serial": "3446457",
+                "serial": "123456789-000@123456789:001",
                 "action": "message.create",
                 "text": "hello response",
                 "metadata": [:],
                 "headers": [:],
                 "version": [
-                    "serial": "3446457",
+                    "serial": "123456789-000@123456789:001",
                 ],
                 "timestamp": 1_730_943_051_269,
             ],