Observe room info updates and automatically dismiss the room if meanwhile left or banned (#4122)

* Fix #3302 - Observe room info updates and automatically dismiss the room if meanwhile left or banned.

ElementX/Sources/FlowCoordinators/RoomFlowCoordinator.swift

@@ -273,6 +273,19 @@ class RoomFlowCoordinator: FlowCoordinatorProtocol {
         // early return above could result in trying to access the room's timeline provider
         // before it has been set which triggers a fatal error.
         self.roomProxy = roomProxy
+        
+        // Subscribe to room info updates in order to detect rooms being left on other devices
+        // and react accordingly by dismissing this flow coordinator.
+        self.roomProxy.infoPublisher
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] info in
+                guard let self else { return }
+                
+                if info.membership == .left || info.membership == .banned, stateMachine.state != .complete {
+                    stateMachine.tryEvent(.dismissFlow)
+                }
+            }
+            .store(in: &cancellables)
     }
     
     // swiftlint:disable:next function_body_length

ElementX/Sources/Mocks/JoinedRoomProxyMock.swift

@@ -43,7 +43,10 @@ struct JoinedRoomProxyMockConfiguration {
     var canUserPin = true
     
     var shouldUseAutoUpdatingTimeline = false
+    
     var joinRule: JoinRule?
+    var membership: Membership = .joined
+    
     var isVisibleInPublicDirectory = false
 }
 
@@ -151,7 +154,7 @@ extension RoomInfo {
                   isFavourite: false,
                   canonicalAlias: configuration.canonicalAlias,
                   alternativeAliases: configuration.alternativeAliases,
-                  membership: .joined,
+                  membership: configuration.membership,
                   inviter: configuration.inviter.map { RoomMember(userId: $0.userID,
                                                                   displayName: $0.displayName,
                                                                   avatarUrl: $0.avatarURL?.absoluteString,

UnitTests/Sources/RoomFlowCoordinatorTests.swift

@@ -268,6 +268,31 @@ class RoomFlowCoordinatorTests: XCTestCase {
         XCTAssertNil(navigationStackCoordinator.sheetCoordinator, "The media upload sheet shouldn't be shown when sharing text.")
     }
     
+    func testLeavingRoom() async throws {
+        await setupRoomFlowCoordinator()
+        
+        var configuration = JoinedRoomProxyMockConfiguration()
+        let roomProxy = JoinedRoomProxyMock(configuration)
+        
+        let roomInfoSubject = CurrentValueSubject<RoomInfoProxy, Never>(.init(roomInfo: .init(configuration)))
+        roomProxy.infoPublisher = roomInfoSubject.asCurrentValuePublisher()
+        
+        clientProxy.roomForIdentifierClosure = { _ in
+            .joined(roomProxy)
+        }
+        
+        try await process(route: .room(roomID: "1", via: []))
+        
+        let fulfillment = deferFulfillment(roomFlowCoordinator.actions) { action in
+            action == .finished
+        }
+        
+        configuration.membership = .left
+        roomInfoSubject.send(.init(roomInfo: .init(configuration)))
+        
+        try await fulfillment.fulfill()
+    }
+    
     // MARK: - Private
     
     private func process(route: AppRoute) async throws {