possibly fixed timing issue in test

MQTTnet.Core/Server/IMqttClientRetainedMessageManager.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Server
+{
+    public interface IMqttClientRetainedMessageManager
+    {
+        Task LoadMessagesAsync();
+
+        Task HandleMessageAsync(string clientId, MqttApplicationMessage applicationMessage);
+
+        List<MqttApplicationMessage> GetMessages(MqttSubscribePacket subscribePacket);
+    }
+}

MQTTnet.Core/Server/MqttClientRetainedMessagesManager.cs

@@ -8,7 +8,7 @@ using Microsoft.Extensions.Options;
 
 namespace MQTTnet.Core.Server
 {
-    public sealed class MqttClientRetainedMessagesManager
+    public sealed class MqttClientRetainedMessagesManager : IMqttClientRetainedMessageManager
     {
         private readonly Dictionary<string, MqttApplicationMessage> _retainedMessages = new Dictionary<string, MqttApplicationMessage>();
         private readonly ILogger<MqttClientRetainedMessagesManager> _logger;

MQTTnet.Core/Server/MqttClientSession.cs

@@ -15,6 +15,7 @@ namespace MQTTnet.Core.Server
 {
     public sealed class MqttClientSession : IDisposable
     {
+        private readonly IMqttClientRetainedMessageManager _clientRetainedMessageManager;
         private readonly HashSet<ushort> _unacknowledgedPublishPackets = new HashSet<ushort>();
 
         private readonly MqttClientSubscriptionsManager _subscriptionsManager;
@@ -33,10 +34,12 @@ namespace MQTTnet.Core.Server
             MqttClientSessionsManager sessionsManager,
             MqttClientSubscriptionsManager subscriptionsManager,
             ILogger<MqttClientSession> logger, 
-            ILogger<MqttClientPendingMessagesQueue> messageQueueLogger)
+            ILogger<MqttClientPendingMessagesQueue> messageQueueLogger,
+            IMqttClientRetainedMessageManager clientRetainedMessageManager)
         {
+            _clientRetainedMessageManager = clientRetainedMessageManager ?? throw new ArgumentNullException(nameof(clientRetainedMessageManager));
             _sessionsManager = sessionsManager ?? throw new ArgumentNullException(nameof(sessionsManager));
-            _subscriptionsManager = subscriptionsManager ?? throw new ArgumentNullException(nameof(sessionsManager));
+            _subscriptionsManager = subscriptionsManager ?? throw new ArgumentNullException(nameof(subscriptionsManager));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
 
             ClientId = clientId;
@@ -206,7 +209,7 @@ namespace MQTTnet.Core.Server
 
         private void EnqueueRetainedMessages(MqttSubscribePacket subscribePacket)
         {
-            var retainedMessages = _sessionsManager.RetainedMessagesManager.GetMessages(subscribePacket);
+            var retainedMessages = _clientRetainedMessageManager.GetMessages(subscribePacket);
             foreach (var publishPacket in retainedMessages)
             {
                 EnqueuePublishPacket(publishPacket.ToPublishPacket());
@@ -227,7 +230,7 @@ namespace MQTTnet.Core.Server
 
             if (applicationMessage.Retain)
             {
-                await _sessionsManager.RetainedMessagesManager.HandleMessageAsync(ClientId, applicationMessage);
+                await _clientRetainedMessageManager.HandleMessageAsync(ClientId, applicationMessage);
             }
 
             switch (applicationMessage.QualityOfServiceLevel)

MQTTnet.Core/Server/MqttClientSessionsManager.cs

@@ -24,12 +24,10 @@ namespace MQTTnet.Core.Server
         public MqttClientSessionsManager(
             IOptions<MqttServerOptions> options, 
             ILogger<MqttClientSessionsManager> logger,
-            MqttClientRetainedMessagesManager retainedMessagesManager, 
             IMqttClientSesssionFactory clientSesssionFactory)
         {
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
             _options = options.Value ?? throw new ArgumentNullException(nameof(options));
-            RetainedMessagesManager = retainedMessagesManager ?? throw new ArgumentNullException(nameof(options));
             _clientSesssionFactory = clientSesssionFactory ?? throw new ArgumentNullException(nameof(clientSesssionFactory));
         }
 
@@ -37,8 +35,6 @@ namespace MQTTnet.Core.Server
         public event EventHandler<MqttClientDisconnectedEventArgs> ClientDisconnected;
         public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
 
-        public MqttClientRetainedMessagesManager RetainedMessagesManager { get; }
-
         public async Task RunClientSessionAsync(IMqttCommunicationAdapter clientAdapter, CancellationToken cancellationToken)
         {
             var clientId = string.Empty;

MQTTnet.Core/Server/MqttServer.cs

@@ -6,11 +6,13 @@ using MQTTnet.Core.Adapter;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using System.Linq;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace MQTTnet.Core.Server
 {
     public class MqttServer : IMqttServer
     {
+        private readonly IMqttClientRetainedMessageManager _clientRetainedMessageManager;
         private readonly ILogger<MqttServer> _logger;
         private readonly MqttClientSessionsManager _clientSessionsManager;
         private readonly ICollection<IMqttServerAdapter> _adapters;
@@ -18,11 +20,18 @@ namespace MQTTnet.Core.Server
 
         private CancellationTokenSource _cancellationTokenSource;
 
-        public MqttServer(IOptions<MqttServerOptions> options, IEnumerable<IMqttServerAdapter> adapters, ILogger<MqttServer> logger, MqttClientSessionsManager clientSessionsManager)
+        public MqttServer(
+            IOptions<MqttServerOptions> options, 
+            IEnumerable<IMqttServerAdapter> adapters,
+            ILogger<MqttServer> logger,
+            MqttClientSessionsManager clientSessionsManager,
+            IMqttClientRetainedMessageManager clientRetainedMessageManager
+            )
         {
             _options = options.Value ?? throw new ArgumentNullException(nameof(options));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
             _clientSessionsManager = clientSessionsManager ?? throw new ArgumentNullException(nameof(clientSessionsManager));
+            _clientRetainedMessageManager = clientRetainedMessageManager ?? throw new ArgumentNullException(nameof(clientRetainedMessageManager));
 
             if (adapters == null)
             {
@@ -79,7 +88,7 @@ namespace MQTTnet.Core.Server
 
             _cancellationTokenSource = new CancellationTokenSource();
 
-            await _clientSessionsManager.RetainedMessagesManager.LoadMessagesAsync();
+            await _clientRetainedMessageManager.LoadMessagesAsync();
 
             foreach (var adapter in _adapters)
             {