Change room lifecycle contributor into a protocol

For an upcoming feature, I’m going to want to add methods to the
contributor itself, and hence want to be able to mock it.

Sources/AblyChat/RoomLifecycleManager.swift

@@ -13,15 +13,16 @@ internal protocol RoomLifecycleContributorChannel: Sendable {
     var errorReason: ARTErrorInfo? { get async }
 }
 
-internal actor RoomLifecycleManager<Channel: RoomLifecycleContributorChannel> {
-    /// A realtime channel that contributes to the room lifecycle.
-    internal struct Contributor {
-        /// The room feature that this contributor corresponds to. Used only for choosing which error to throw when a contributor operation fails.
-        internal var feature: RoomFeature
+/// A realtime channel that contributes to the room lifecycle.
+internal protocol RoomLifecycleContributor: Sendable {
+    associatedtype Channel: RoomLifecycleContributorChannel
 
-        internal var channel: Channel
-    }
+    /// The room feature that this contributor corresponds to. Used only for choosing which error to throw when a contributor operation fails.
+    var feature: RoomFeature { get }
+    var channel: Channel { get }
+}
 
+internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
     internal private(set) var current: RoomLifecycle
     internal private(set) var error: ARTErrorInfo?
 

Tests/AblyChatTests/Mocks/MockRoomLifecycleContributor.swift

@@ -0,0 +1,11 @@
+@testable import AblyChat
+
+actor MockRoomLifecycleContributor: RoomLifecycleContributor {
+    nonisolated let feature: RoomFeature
+    nonisolated let channel: MockRoomLifecycleContributorChannel
+
+    init(feature: RoomFeature, channel: MockRoomLifecycleContributorChannel) {
+        self.feature = feature
+        self.channel = channel
+    }
+}

Tests/AblyChatTests/RoomLifecycleManagerTests.swift

@@ -29,9 +29,9 @@ struct RoomLifecycleManagerTests {
 
     private func createManager(
         forTestingWhatHappensWhenCurrentlyIn current: RoomLifecycle? = nil,
-        contributors: [RoomLifecycleManager<MockRoomLifecycleContributorChannel>.Contributor] = [],
+        contributors: [MockRoomLifecycleContributor] = [],
         clock: SimpleClock = MockSimpleClock()
-    ) async -> RoomLifecycleManager<MockRoomLifecycleContributorChannel> {
+    ) async -> RoomLifecycleManager<MockRoomLifecycleContributor> {
         await .init(
             testsOnly_current: current,
             contributors: contributors,
@@ -45,7 +45,7 @@ struct RoomLifecycleManagerTests {
         feature: RoomFeature = .messages, // Arbitrarily chosen, its value only matters in test cases where we check which error is thrown
         attachBehavior: MockRoomLifecycleContributorChannel.AttachOrDetachBehavior? = nil,
         detachBehavior: MockRoomLifecycleContributorChannel.AttachOrDetachBehavior? = nil
-    ) -> RoomLifecycleManager<MockRoomLifecycleContributorChannel>.Contributor {
+    ) -> MockRoomLifecycleContributor {
         .init(
             feature: feature,
             channel: .init(