Merge pull request #104 from ably/80-always-transition-to-SYNCING-on-ATTACHED

Always transition to `SYNCING` on receipt of `ATTACHED`

Author: lawrence-forooghian

Sources/AblyLiveObjects/Internal/InternalDefaultRealtimeObjects.swift

@@ -448,7 +448,7 @@ internal final class InternalDefaultRealtimeObjects: Sendable, LiveMapObjectsPoo
 
         /// The state that drives the emission of the `syncing` and `synced` events and which stores the sync sequence data.
         ///
-        /// This manipulation of this value is based on https://github.com/ably/ably-js/blob/0c5baa9273ca87aec6ca594833d59c4c4d2dddbb/src/plugins/objects/objects.ts.
+        /// This manipulation of this value is based on https://github.com/ably/ably-js/blob/e280bff11a4a7627362c5185e764b7ebd0490570/src/plugins/objects/objects.ts.
         /// TODO: Bring in line with spec once it exists (https://github.com/ably/ably-liveobjects-swift-plugin/issues/80)
         internal var state = State.initialized
 
@@ -507,8 +507,8 @@ internal final class InternalDefaultRealtimeObjects: Sendable, LiveMapObjectsPoo
 
             onChannelAttachedHasObjects = hasObjects
 
-            if (hasObjects && state.toObjectsSyncState != .syncing) || state.toObjectsSyncState == .initialized {
-                // We will subsequently transition to .synced either by the completion of the RTO4a OBJECT_SYNC, or by the RTO4b no-HAS_OBJECTS case below
+            // We will subsequently transition to .synced either by the completion of the RTO4a OBJECT_SYNC, or by the RTO4b no-HAS_OBJECTS case below
+            if state.toObjectsSyncState != .syncing {
                 transition(to: .syncing(.init(syncSequence: nil)), userCallbackQueue: userCallbackQueue)
             }
 
@@ -523,9 +523,7 @@ internal final class InternalDefaultRealtimeObjects: Sendable, LiveMapObjectsPoo
             // I have, for now, not directly implemented the "perform the actions for object sync completion" of RTO4b4 since my implementation doesn't quite match the model given there; here you only have a SyncObjectsPool if you have an OBJECT_SYNC in progress, which you might not have upon receiving an ATTACHED. Instead I've just implemented what seem like the relevant side effects. Can revisit this if "the actions for object sync completion" get more complex.
 
             // RTO4b3, RTO4b4, RTO4b5, RTO5c3, RTO5c4, RTO5c5
-            if state.toObjectsSyncState != .synced {
-                transition(to: .synced, userCallbackQueue: userCallbackQueue)
-            }
+            transition(to: .synced, userCallbackQueue: userCallbackQueue)
         }
 
         /// Implements the `OBJECT_SYNC` handling of RTO5.

Sources/AblyLiveObjects/Internal/InternalLiveObject.swift

@@ -35,7 +35,7 @@ internal extension InternalLiveObject {
         resetDataToZeroValued()
 
         // Emit the deleted lifecycle event
-        // Taken from https://github.com/ably/ably-js/blob/0c5baa9273ca87aec6ca594833d59c4c4d2dddbb/src/plugins/objects/liveobject.ts#L168
+        // Taken from https://github.com/ably/ably-js/blob/e280bff11a4a7627362c5185e764b7ebd0490570/src/plugins/objects/liveobject.ts#L168
         // TODO: Bring in line with spec once it exists (https://github.com/ably/ably-liveobjects-swift-plugin/issues/77)
         liveObjectMutableState.emitLifecycleEvent(.deleted, on: userCallbackQueue)
     }

Sources/AblyLiveObjects/Internal/ObjectsSyncState.swift

@@ -1,6 +1,6 @@
 /// The type that the spec uses to represent the client's state of syncing its local Objects data with the server.
 ///
-/// (TODO: This isn't actually in the spec yet, will specify in https://github.com/ably/ably-liveobjects-swift-plugin/issues/80; it's currently copied from https://github.com/ably/ably-js/blob/0c5baa9273ca87aec6ca594833d59c4c4d2dddbb/src/plugins/objects/objects.ts)
+/// (TODO: This isn't actually in the spec yet, will specify in https://github.com/ably/ably-liveobjects-swift-plugin/issues/80; it's currently copied from https://github.com/ably/ably-js/blob/e280bff11a4a7627362c5185e764b7ebd0490570/src/plugins/objects/objects.ts)
 internal enum ObjectsSyncState {
     case initialized
     case syncing

Tests/AblyLiveObjectsTests/InternalDefaultRealtimeObjectsTests.swift

@@ -1475,9 +1475,12 @@ struct InternalDefaultRealtimeObjectsTests {
                 ),
 
                 .init(
-                    description: "ATTACHED with HAS_OBJECTS false once SYNCED should not provoke further events",
+                    description: "ATTACHED with HAS_OBJECTS false once SYNCED emits SYNCING and then SYNCED",
                     channelEvents: [.attached(hasObjects: false), .attached(hasObjects: false)],
-                    expectedSyncEvents: [.syncing, .synced],
+                    expectedSyncEvents: [
+                        .syncing, .synced, // The initial SYNCED
+                        .syncing, .synced, // From the subsequent ATTACHED
+                    ],
                 ),
 
                 .init(