Populate DebugException on some cancellation scenarios (#1780)

Author: JamesNK

src/Grpc.Net.Client/Internal/GrpcCall.cs

@@ -248,9 +248,9 @@ public void EnsureNotDisposed()
             }
         }
 
-        public Exception CreateCanceledStatusException()
+        public Exception CreateCanceledStatusException(Exception? ex = null)
         {
-            var status = (CallTask.IsCompletedSuccessfully()) ? CallTask.Result : new Status(StatusCode.Cancelled, string.Empty);
+            var status = (CallTask.IsCompletedSuccessfully()) ? CallTask.Result : new Status(StatusCode.Cancelled, string.Empty, ex);
             return CreateRpcException(status);
         }
 
@@ -672,7 +672,7 @@ internal bool ResolveException(string summary, Exception ex, [NotNull] out Statu
         {
             if (ex is OperationCanceledException)
             {
-                status = (CallTask.IsCompletedSuccessfully()) ? CallTask.Result : new Status(StatusCode.Cancelled, string.Empty);
+                status = (CallTask.IsCompletedSuccessfully()) ? CallTask.Result : new Status(StatusCode.Cancelled, string.Empty, ex);
                 if (!Channel.ThrowOperationCanceledOnCancellation)
                 {
                     resolvedException = CreateRpcException(status.Value);

src/Grpc.Net.Client/Internal/HttpContentClientStreamReader.cs

@@ -65,7 +65,8 @@ public Task<bool> MoveNext(CancellationToken cancellationToken)
             {
                 if (!_call.Channel.ThrowOperationCanceledOnCancellation)
                 {
-                    return Task.FromException<bool>(_call.CreateCanceledStatusException());
+                    var ex = _call.CreateCanceledStatusException(new OperationCanceledException(_call.CancellationToken));
+                    return Task.FromException<bool>(ex);
                 }
                 else
                 {
@@ -190,7 +191,7 @@ private async Task<bool> MoveNextCore(CancellationToken cancellationToken)
 
                 if (!_call.Channel.ThrowOperationCanceledOnCancellation)
                 {
-                    throw _call.CreateCanceledStatusException();
+                    throw _call.CreateCanceledStatusException(ex);
                 }
                 else
                 {

src/Grpc.Net.Client/Internal/HttpContentClientStreamWriter.cs

@@ -176,9 +176,9 @@ public async Task WriteAsyncCore<TState>(Func<GrpcCall<TRequest, TResponse>, Str
 
                 GrpcEventSource.Log.MessageSent();
             }
-            catch (OperationCanceledException) when (!_call.Channel.ThrowOperationCanceledOnCancellation)
+            catch (OperationCanceledException ex) when (!_call.Channel.ThrowOperationCanceledOnCancellation)
             {
-                throw _call.CreateCanceledStatusException();
+                throw _call.CreateCanceledStatusException(ex);
             }
         }
     }

test/FunctionalTests/Client/StreamingTests.cs

@@ -424,6 +424,7 @@ async Task<DataComplete> ClientStreamedData(IAsyncStreamReader<DataMessage> requ
             // Assert
             Assert.AreEqual(StatusCode.Cancelled, ex.StatusCode);
             Assert.AreEqual(StatusCode.Cancelled, call.GetStatus().StatusCode);
+            Assert.IsInstanceOf<OperationCanceledException>(call.GetStatus().DebugException);
 
             AssertHasLog(LogLevel.Information, "GrpcStatusError", "Call failed with gRPC error status. Status code: 'Cancelled', Message: ''.");