Exceptions thrown by UIA server in UI thread in WPF should be caught …

…and redirected to automating thread in order to report error correctly. Otherwise automated app just crashes as with usual uncaught exception in dispatcher. On UIA client side added UiaCallFailedException because otherwise it is TargetInvocationException without any details, which is very common.

ManagedUiaCustomizationCore/AutomationPeerAugmentationHelper.cs

@@ -159,6 +159,42 @@ public object WrapObjectReplacer(AutomationPeer peer, object iface)
             }
         }
 
+        private static void GuardUiaServerInvocation(Action invocation, Dispatcher dispatcher)
+        {
+            if (dispatcher == null)
+                throw new ElementNotAvailableException();
+            Exception remoteException = null;
+            bool completed = false;
+            dispatcher.Invoke(DispatcherPriority.Send, TimeSpan.FromMinutes(3.0), (Action)(() =>
+            {
+                try
+                {
+                    invocation();
+                }
+                catch (Exception e)
+                {
+                    remoteException = e;
+                }
+                catch
+                {
+                    remoteException = null;
+                }
+                finally
+                {
+                    completed = true;
+                }
+            }));
+            if (completed)
+            {
+                if (remoteException != null)
+                    throw remoteException;
+            }
+            else if (dispatcher.HasShutdownStarted)
+                throw new InvalidOperationException("AutomationDispatcherShutdown");
+            else
+                throw new TimeoutException("AutomationTimeout");
+        }
+
         private class StandalonePropertyGetter
         {
             private readonly AutomationProperty _property;
@@ -172,7 +208,9 @@ public object Getter(AutomationPeer peer)
             {
                 var propertyProvider = peer as IStandalonePropertyProvider;
                 if (propertyProvider == null) return null;
-                return propertyProvider.GetPropertyValue(_property);
+                object result = null;
+                GuardUiaServerInvocation(() => result = propertyProvider.GetPropertyValue(_property), peer.Dispatcher);
+                return result;
             }
         }
 
@@ -187,15 +225,7 @@ public SendingToUIThreadInterceptor(AutomationPeer peer)
 
             public void Intercept(IInvocation invocation)
             {
-                if (_dispatcher.CheckAccess())
-                {
-                    invocation.Proceed();
-                }
-                else
-                {
-                    Action a = invocation.Proceed;
-                    _dispatcher.Invoke(a);
-                }
+                GuardUiaServerInvocation(invocation.Proceed, _dispatcher);
             }
         }
     }

ManagedUiaCustomizationCore/ManagedUiaCustomizationCore.csproj

@@ -81,6 +81,7 @@
     <Compile Include="Schema\UiaPatternInfoHelper.cs" />
     <Compile Include="Schema\UiaPropertyInfoHelper.cs" />
     <Compile Include="AttributeDrivenPatternHelpers\UiaTypesHelper.cs" />
+    <Compile Include="UiaCallFailedException.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />

ManagedUiaCustomizationCore/NativeMethods.cs

@@ -33,6 +33,14 @@ public static void WrapUiaComCall(Action call)
                     throw newEx;
                 throw;
             }
+            catch (Exception e)
+            {
+                throw new UiaCallFailedException("Automation call failure", e);
+            }
+            catch
+            {
+                throw new UiaCallFailedException("Automation call failure");
+            }
         }
 
         #region Taken from UIAComWrapper - exception wrapping

ManagedUiaCustomizationCore/UiaCallFailedException.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Runtime.Serialization;
+
+namespace ManagedUiaCustomizationCore
+{
+    [Serializable]
+    public class UiaCallFailedException : Exception
+    {
+        public UiaCallFailedException()
+        {
+        }
+
+        public UiaCallFailedException(string message) : base(message)
+        {
+        }
+
+        public UiaCallFailedException(string message, Exception inner) : base(message, inner)
+        {
+        }
+
+        protected UiaCallFailedException(
+            SerializationInfo info,
+            StreamingContext context) : base(info, context)
+        {
+        }
+    }
+}