diff --git a/src/Transports.AspNetCore/WebSockets/AsyncMessagePump.cs b/src/Transports.AspNetCore/WebSockets/AsyncMessagePump.cs
index c9da3dcf..6c3da2d6 100644
--- a/src/Transports.AspNetCore/WebSockets/AsyncMessagePump.cs
+++ b/src/Transports.AspNetCore/WebSockets/AsyncMessagePump.cs
@@ -22,6 +22,21 @@ internal class AsyncMessagePump<T>
     private readonly Func<T, Task> _callback;
     private readonly Queue<ValueTask<T>> _queue = new();
 
+    /// <summary>
+    /// Returns the number of messages in the queue.
+    /// This count includes any message currently being processed.
+    /// </summary>
+    public int Count
+    {
+        get
+        {
+            lock (_queue)
+            {
+                return _queue.Count;
+            }
+        }
+    }
+
     /// <summary>
     /// Initializes a new instance with the specified asynchronous callback delegate.
     /// </summary>
diff --git a/src/Transports.AspNetCore/WebSockets/WebSocketConnection.cs b/src/Transports.AspNetCore/WebSockets/WebSocketConnection.cs
index e75f2349..40c92ddb 100644
--- a/src/Transports.AspNetCore/WebSockets/WebSocketConnection.cs
+++ b/src/Transports.AspNetCore/WebSockets/WebSocketConnection.cs
@@ -43,6 +43,13 @@ public class WebSocketConnection : IWebSocketConnection
     /// <inheritdoc/>
     public HttpContext HttpContext { get; }
 
+    /// <summary>
+    /// Returns the number of packets waiting in the send queue, including
+    /// messages, keep-alive packets, and the close message.
+    /// This count includes any packet currently being processed.
+    /// </summary>
+    protected int SendQueueCount => _pump.Count;
+
     /// <summary>
     /// Initializes an instance with the specified parameters.
     /// </summary>
@@ -218,7 +225,7 @@ public Task CloseAsync(int eventId, string? description)
     /// <remarks>
     /// The message is posted to a queue and execution returns immediately.
     /// </remarks>
-    public Task SendMessageAsync(OperationMessage message)
+    public virtual Task SendMessageAsync(OperationMessage message)
     {
         _pump.Post(new Message { OperationMessage = message });
         return Task.CompletedTask;
diff --git a/tests/ApiApprovalTests/net50+net60+net80/GraphQL.Server.Transports.AspNetCore.approved.txt b/tests/ApiApprovalTests/net50+net60+net80/GraphQL.Server.Transports.AspNetCore.approved.txt
index 066e8a44..94573a13 100644
--- a/tests/ApiApprovalTests/net50+net60+net80/GraphQL.Server.Transports.AspNetCore.approved.txt
+++ b/tests/ApiApprovalTests/net50+net60+net80/GraphQL.Server.Transports.AspNetCore.approved.txt
@@ -340,6 +340,7 @@ namespace GraphQL.Server.Transports.AspNetCore.WebSockets
         public Microsoft.AspNetCore.Http.HttpContext HttpContext { get; }
         public System.DateTime LastMessageSentAt { get; }
         public System.Threading.CancellationToken RequestAborted { get; }
+        protected int SendQueueCount { get; }
         public System.Threading.Tasks.Task CloseAsync() { }
         public System.Threading.Tasks.Task CloseAsync(int eventId, string? description) { }
         public virtual void Dispose() { }
@@ -348,7 +349,7 @@ namespace GraphQL.Server.Transports.AspNetCore.WebSockets
         protected virtual System.Threading.Tasks.Task OnDispatchMessageAsync(GraphQL.Server.Transports.AspNetCore.WebSockets.IOperationMessageProcessor operationMessageProcessor, GraphQL.Transport.OperationMessage message) { }
         protected virtual System.Threading.Tasks.Task OnNonGracefulShutdownAsync(bool receivedCloseMessage, bool sentCloseMessage) { }
         protected virtual System.Threading.Tasks.Task OnSendMessageAsync(GraphQL.Transport.OperationMessage message) { }
-        public System.Threading.Tasks.Task SendMessageAsync(GraphQL.Transport.OperationMessage message) { }
+        public virtual System.Threading.Tasks.Task SendMessageAsync(GraphQL.Transport.OperationMessage message) { }
     }
 }
 namespace GraphQL.Server.Transports.AspNetCore.WebSockets.GraphQLWs
diff --git a/tests/ApiApprovalTests/netcoreapp21+netstandard20/GraphQL.Server.Transports.AspNetCore.approved.txt b/tests/ApiApprovalTests/netcoreapp21+netstandard20/GraphQL.Server.Transports.AspNetCore.approved.txt
index 1216fed0..6e037d49 100644
--- a/tests/ApiApprovalTests/netcoreapp21+netstandard20/GraphQL.Server.Transports.AspNetCore.approved.txt
+++ b/tests/ApiApprovalTests/netcoreapp21+netstandard20/GraphQL.Server.Transports.AspNetCore.approved.txt
@@ -358,6 +358,7 @@ namespace GraphQL.Server.Transports.AspNetCore.WebSockets
         public Microsoft.AspNetCore.Http.HttpContext HttpContext { get; }
         public System.DateTime LastMessageSentAt { get; }
         public System.Threading.CancellationToken RequestAborted { get; }
+        protected int SendQueueCount { get; }
         public System.Threading.Tasks.Task CloseAsync() { }
         public System.Threading.Tasks.Task CloseAsync(int eventId, string? description) { }
         public virtual void Dispose() { }
@@ -366,7 +367,7 @@ namespace GraphQL.Server.Transports.AspNetCore.WebSockets
         protected virtual System.Threading.Tasks.Task OnDispatchMessageAsync(GraphQL.Server.Transports.AspNetCore.WebSockets.IOperationMessageProcessor operationMessageProcessor, GraphQL.Transport.OperationMessage message) { }
         protected virtual System.Threading.Tasks.Task OnNonGracefulShutdownAsync(bool receivedCloseMessage, bool sentCloseMessage) { }
         protected virtual System.Threading.Tasks.Task OnSendMessageAsync(GraphQL.Transport.OperationMessage message) { }
-        public System.Threading.Tasks.Task SendMessageAsync(GraphQL.Transport.OperationMessage message) { }
+        public virtual System.Threading.Tasks.Task SendMessageAsync(GraphQL.Transport.OperationMessage message) { }
     }
 }
 namespace GraphQL.Server.Transports.AspNetCore.WebSockets.GraphQLWs
diff --git a/tests/ApiApprovalTests/netcoreapp31/GraphQL.Server.Transports.AspNetCore.approved.txt b/tests/ApiApprovalTests/netcoreapp31/GraphQL.Server.Transports.AspNetCore.approved.txt
index 685396c3..38f847f6 100644
--- a/tests/ApiApprovalTests/netcoreapp31/GraphQL.Server.Transports.AspNetCore.approved.txt
+++ b/tests/ApiApprovalTests/netcoreapp31/GraphQL.Server.Transports.AspNetCore.approved.txt
@@ -340,6 +340,7 @@ namespace GraphQL.Server.Transports.AspNetCore.WebSockets
         public Microsoft.AspNetCore.Http.HttpContext HttpContext { get; }
         public System.DateTime LastMessageSentAt { get; }
         public System.Threading.CancellationToken RequestAborted { get; }
+        protected int SendQueueCount { get; }
         public System.Threading.Tasks.Task CloseAsync() { }
         public System.Threading.Tasks.Task CloseAsync(int eventId, string? description) { }
         public virtual void Dispose() { }
@@ -348,7 +349,7 @@ namespace GraphQL.Server.Transports.AspNetCore.WebSockets
         protected virtual System.Threading.Tasks.Task OnDispatchMessageAsync(GraphQL.Server.Transports.AspNetCore.WebSockets.IOperationMessageProcessor operationMessageProcessor, GraphQL.Transport.OperationMessage message) { }
         protected virtual System.Threading.Tasks.Task OnNonGracefulShutdownAsync(bool receivedCloseMessage, bool sentCloseMessage) { }
         protected virtual System.Threading.Tasks.Task OnSendMessageAsync(GraphQL.Transport.OperationMessage message) { }
-        public System.Threading.Tasks.Task SendMessageAsync(GraphQL.Transport.OperationMessage message) { }
+        public virtual System.Threading.Tasks.Task SendMessageAsync(GraphQL.Transport.OperationMessage message) { }
     }
 }
 namespace GraphQL.Server.Transports.AspNetCore.WebSockets.GraphQLWs
diff --git a/tests/Transports.AspNetCore.Tests/WebSockets/TestWebSocketConnection.cs b/tests/Transports.AspNetCore.Tests/WebSockets/TestWebSocketConnection.cs
index 8c3b8860..14ac2b17 100644
--- a/tests/Transports.AspNetCore.Tests/WebSockets/TestWebSocketConnection.cs
+++ b/tests/Transports.AspNetCore.Tests/WebSockets/TestWebSocketConnection.cs
@@ -25,4 +25,6 @@ public Task Do_OnCloseOutputAsync(WebSocketCloseStatus closeStatus, string? clos
 
     public TimeSpan Get_DefaultDisconnectionTimeout
         => DefaultDisconnectionTimeout;
+
+    public int Get_SendQueueCount => base.SendQueueCount;
 }
diff --git a/tests/Transports.AspNetCore.Tests/WebSockets/WebSocketConnectionTests.cs b/tests/Transports.AspNetCore.Tests/WebSockets/WebSocketConnectionTests.cs
index b67f134b..6f140822 100644
--- a/tests/Transports.AspNetCore.Tests/WebSockets/WebSocketConnectionTests.cs
+++ b/tests/Transports.AspNetCore.Tests/WebSockets/WebSocketConnectionTests.cs
@@ -597,18 +597,44 @@ public async Task CloseConnectionAsync_Specific()
     public async Task SendMessageAsync()
     {
         var message = new OperationMessage();
+        _mockConnection.Setup(x => x.SendMessageAsync(It.IsAny<OperationMessage>())).CallBase().Verifiable();
         _mockConnection.Protected().Setup<Task>("OnSendMessageAsync", message)
             .Returns(Task.CompletedTask).Verifiable();
         await _connection.SendMessageAsync(message);
         _mockConnection.Verify();
     }
 
+    [Fact]
+    public async Task MessageCountAsync()
+    {
+        var tc = new TaskCompletionSource<bool>();
+        var message = new OperationMessage();
+        _mockConnection.Setup(x => x.SendMessageAsync(It.IsAny<OperationMessage>())).CallBase().Verifiable();
+        _mockConnection.Protected().Setup<Task>("OnSendMessageAsync", message)
+            .Returns(tc.Task).Verifiable();
+        await _connection.SendMessageAsync(message);
+        _connection.Get_SendQueueCount.ShouldBe(1);
+        await _connection.SendMessageAsync(message);
+        _connection.Get_SendQueueCount.ShouldBe(2);
+        tc.SetResult(true);
+        for (int i = 0; i < 100; i++)
+        {
+            if (_connection.Get_SendQueueCount != 0)
+                await Task.Delay(100);
+            else
+                break;
+        }
+        _connection.Get_SendQueueCount.ShouldBe(0);
+        _mockConnection.Verify();
+    }
+
     [Fact]
     public async Task LastMessageSentAt()
     {
         var oldTime = _connection.LastMessageSentAt;
         await Task.Delay(100);
         var message = new OperationMessage();
+        _mockConnection.Setup(x => x.SendMessageAsync(It.IsAny<OperationMessage>())).CallBase().Verifiable();
         _mockConnection.Protected().Setup<Task>("OnSendMessageAsync", message)
             .Returns(Task.CompletedTask).Verifiable();
         await _connection.SendMessageAsync(message);
@@ -623,6 +649,7 @@ public async Task DoNotSendMessagesAfterOutputIsClosed()
     {
         // send a message
         var message = new OperationMessage();
+        _mockConnection.Setup(x => x.SendMessageAsync(It.IsAny<OperationMessage>())).CallBase().Verifiable();
         _mockConnection.Protected().SetupGet<TimeSpan>("DefaultDisconnectionTimeout").CallBase().Verifiable();
         _mockConnection.Protected().Setup<Task>("OnSendMessageAsync", message)
             .Returns(Task.CompletedTask).Verifiable();