Don't reference ConnectAsync's CancellationToken while waiting for the first message

src/MagicOnion.Client/StreamingHubClientBase.cs

@@ -1,4 +1,4 @@
-using Grpc.Core;
+using Grpc.Core;
 using MagicOnion.Client.Internal;
 using MagicOnion.Internal;
 using MagicOnion.Internal.Buffers;
@@ -242,20 +242,16 @@ internal async Task __ConnectAndSubscribeAsync(CancellationToken connectAndSubsc
             subscriptionToken = CancellationTokenSource.CreateLinkedTokenSource(heartbeatManager.TimeoutToken, subscriptionCts.Token).Token;
         }
 
-        var firstMoveNextTask = reader.MoveNext(CancellationTokenSource.CreateLinkedTokenSource(connectAndSubscribeCancellationToken, subscriptionToken).Token);
+        var firstMoveNextTask = reader.MoveNext(subscriptionToken);
         if (firstMoveNextTask.IsFaulted || messageVersion == null)
         {
             // NOTE: Grpc.Net:
             //           If an error is returned from `StreamingHub.Connect` method on a server-side,
             //           ResponseStream.MoveNext synchronously returns a task that is `IsFaulted = true`.
             //           `ConnectAsync` method should throw an exception here immediately.
-            //       C-core:
-            //           `firstMoveNextTask` is incomplete task (`IsFaulted = false`) whether ResponseHeadersAsync is failed or not.
-            //           If the channel is disconnected or the server returns an error (StatusCode != OK), awaiting the Task will throw an exception.
             await firstMoveNextTask.ConfigureAwait(false);
 
-            // NOTE: C-core: If the execution reaches here, Connect method returns without any error (StatusCode = OK). but MessageVersion isn't provided from the server.
-            throw new RpcException(new Status(StatusCode.Internal, $"The request started successfully (StatusCode = OK), but the StreamingHub client has failed to negotiate with the server."));
+            throw new RpcException(new Status(StatusCode.Internal, $"The request started successfully (StatusCode = OK), but the StreamingHub client has failed to negotiate with the server. ServerVersion is missing."));
         }
 
         this.subscription = StartSubscribe(syncContext, firstMoveNextTask, subscriptionToken);

tests/MagicOnion.Client.Tests/StreamingHubTest.cs

@@ -1,8 +1,9 @@
-using MagicOnion.Client.DynamicClient;
+using MagicOnion.Client.DynamicClient;
 using Microsoft.Extensions.Time.Testing;
 using System.Buffers;
 using System.Diagnostics;
 using System.Reflection;
+using System.Threading;
 
 namespace MagicOnion.Client.Tests;
 
@@ -783,6 +784,40 @@ public async Task ConnectAsync_CancellationToken_Timeout()
         Assert.True(disposed);
     }
 
+    [Fact]
+    public async Task ConnectAsync_CancellationToken_Timeout_On_FirstMoveNext()
+    {
+        // Verify that there is no problem when the CancellationToken passed to ConnectAsync is canceled after ConnectAsync and before the first message arrives.
+
+        // Arrange
+        var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+        var connectTimeout = new CancellationTokenSource();
+        var disposed = true;
+        var helper = new StreamingHubClientTestHelper<IGreeterHub, IGreeterHubReceiver>(
+            factoryProvider: DynamicStreamingHubClientFactoryProvider.Instance,
+            onResponseHeaderAsync: metadata => Task.CompletedTask,
+            onDuplexStreamingCallDisposeAction: () =>
+            {
+                disposed = true;
+            });
+
+        // Act
+        var client = await helper.ConnectAsync(connectTimeout.Token);
+        connectTimeout.Cancel();
+
+        // Invoke Hub Method
+        var t = client.Parameter_Zero().WaitAsync(timeout.Token);
+        {
+            // Read a hub method request payload
+            var (messageId, methodId, requestBody) = await helper.ReadRequestAsync<Nil>();
+            // Write a response to the stream
+            helper.WriteResponse(messageId, methodId, 123);
+        }
+        var result = await t;
+
+        // Assert
+        Assert.Equal(123, result);
+    }
 }
 
 public interface IGreeterHubReceiver