Demonstrate the exception that can't be received by client, issue #105.

CoreRemoting.Tests/RpcTests.cs

@@ -538,6 +538,50 @@ public void NonSerializableError_method_throws_Exception()
             }
         }
 
+        [Fact]
+        public void AfterCall_event_handler_can_translate_exceptions_to_improve_diagnostics()
+        {
+            // replace cryptic database error report with a user-friendly error message
+            void AfterCall(object sender, ServerRpcContext ctx)
+            {
+                var errorMsg = ctx.Exception?.Message ?? string.Empty;
+                if (errorMsg.StartsWith("23503:"))
+                    ctx.Exception = new Exception("Deleting clients is not allowed.",
+                        ctx.Exception);
+            }
+
+            _serverFixture.Server.AfterCall += AfterCall;
+            try
+            {
+                using var client = new RemotingClient(new ClientConfig()
+                {
+                    ConnectionTimeout = 5,
+                    InvocationTimeout = 5,
+                    SendTimeout = 5,
+                    Channel = ClientChannel,
+                    MessageEncryption = false,
+                    ServerPort = _serverFixture.Server.Config.NetworkPort
+                });
+
+                client.Connect();
+
+                // simulate a database error on the server-side
+                var proxy = client.CreateProxy<ITestService>();
+                var ex = Assert.Throws<RemoteInvocationException>(() =>
+                    proxy.Error("23503: delete from table 'clients' violates foreign key constraint 'order_client_fk' on table 'orders'"))
+                        .GetInnermostException();
+
+                Assert.NotNull(ex);
+                Assert.Equal("Deleting clients is not allowed.", ex.Message);
+            }
+            finally
+            {
+                // reset the error counter for other tests
+                _serverFixture.ServerErrorCount = 0;
+                _serverFixture.Server.AfterCall -= AfterCall;
+            }
+        }
+
         [Fact]
         public void Failing_component_constructor_throws_RemoteInvocationException()
         {

CoreRemoting/ClientRpcContext.cs

@@ -17,17 +17,17 @@ internal ClientRpcContext()
             UniqueCallKey = Guid.NewGuid();
             WaitHandle = new EventWaitHandle(initialState: false, EventResetMode.ManualReset);
         }
-        
+
         /// <summary>
         /// Gets the unique key of RPC call.
         /// </summary>
         public Guid UniqueCallKey { get; }
-        
+
         /// <summary>
         /// Gets or sets the result message, that was received from server after the call was invoked on server side.
         /// </summary>
         public MethodCallResultMessage ResultMessage { get; set; }
-        
+
         /// <summary>
         /// Gets or sets whether this RPC call is in error state.
         /// </summary>
@@ -37,12 +37,12 @@ internal ClientRpcContext()
         /// Gets or sets an exception that describes an error that occurred on server side RPC invocation.
         /// </summary>
         public RemoteInvocationException RemoteException { get; set; }
-        
+
         /// <summary>
         /// Gets a wait handle that is set, when the response of this RPC call is received from server.
         /// </summary>
         public EventWaitHandle WaitHandle { get; } // TODO: replace with a Task?
-        
+
         /// <summary>
         /// Frees managed resources.
         /// </summary>