Extract MessageFilter to a top level test utility class

src/VisualStudio/IntegrationTest/IntegrationTests/AbstractIntegrationTest.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
-using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.VisualStudio;
 using Microsoft.VisualStudio.IntegrationTest.Utilities;
+using Microsoft.VisualStudio.IntegrationTest.Utilities.Harness;
 using Microsoft.VisualStudio.IntegrationTest.Utilities.Input;
-using Microsoft.Win32.SafeHandles;
 using Xunit;
-using IMessageFilter = Microsoft.VisualStudio.OLE.Interop.IMessageFilter;
-using INTERFACEINFO = Microsoft.VisualStudio.OLE.Interop.INTERFACEINFO;
-using PENDINGMSG = Microsoft.VisualStudio.OLE.Interop.PENDINGMSG;
-using SERVERCALL = Microsoft.VisualStudio.OLE.Interop.SERVERCALL;
 
 namespace Roslyn.VisualStudio.IntegrationTests
 {
@@ -109,110 +103,5 @@ protected KeyPress Shift(VirtualKey virtualKey)
 
         protected KeyPress Alt(VirtualKey virtualKey)
             => new KeyPress(virtualKey, ShiftState.Alt);
-
-        protected class MessageFilter : IMessageFilter, IDisposable
-        {
-            protected const uint CancelCall = ~0U;
-
-            private readonly MessageFilterSafeHandle _messageFilterRegistration;
-            private readonly TimeSpan _timeout;
-            private readonly TimeSpan _retryDelay;
-
-            public MessageFilter()
-                : this(timeout: TimeSpan.FromSeconds(60), retryDelay: TimeSpan.FromMilliseconds(150))
-            {
-            }
-
-            public MessageFilter(TimeSpan timeout, TimeSpan retryDelay)
-            {
-                _timeout = timeout;
-                _retryDelay = retryDelay;
-                _messageFilterRegistration = MessageFilterSafeHandle.Register(this);
-            }
-
-            public virtual uint HandleInComingCall(uint dwCallType, IntPtr htaskCaller, uint dwTickCount, INTERFACEINFO[] lpInterfaceInfo)
-            {
-                return (uint)SERVERCALL.SERVERCALL_ISHANDLED;
-            }
-
-            public virtual uint RetryRejectedCall(IntPtr htaskCallee, uint dwTickCount, uint dwRejectType)
-            {
-                if ((SERVERCALL)dwRejectType != SERVERCALL.SERVERCALL_RETRYLATER
-                    && (SERVERCALL)dwRejectType != SERVERCALL.SERVERCALL_REJECTED)
-                {
-                    return CancelCall;
-                }
-
-                if (dwTickCount >= _timeout.TotalMilliseconds)
-                {
-                    return CancelCall;
-                }
-
-                return (uint)_retryDelay.TotalMilliseconds;
-            }
-
-            public virtual uint MessagePending(IntPtr htaskCallee, uint dwTickCount, uint dwPendingType)
-            {
-                return (uint)PENDINGMSG.PENDINGMSG_WAITDEFPROCESS;
-            }
-
-            protected virtual void Dispose(bool disposing)
-            {
-                if (disposing)
-                {
-                    _messageFilterRegistration.Dispose();
-                }
-            }
-
-            public void Dispose()
-            {
-                Dispose(true);
-                GC.SuppressFinalize(this);
-            }
-        }
-
-        private sealed class MessageFilterSafeHandle : SafeHandleMinusOneIsInvalid
-        {
-            private readonly IntPtr _oldFilter;
-
-            private MessageFilterSafeHandle(IntPtr handle)
-                : base(true)
-            {
-                SetHandle(handle);
-
-                try
-                {
-                    if (CoRegisterMessageFilter(handle, out _oldFilter) != VSConstants.S_OK)
-                    {
-                        throw new InvalidOperationException("Failed to register a new message filter");
-                    }
-                }
-                catch
-                {
-                    SetHandleAsInvalid();
-                    throw;
-                }
-            }
-
-            [DllImport("ole32", SetLastError = true)]
-            private static extern int CoRegisterMessageFilter(IntPtr messageFilter, out IntPtr oldMessageFilter);
-
-            public static MessageFilterSafeHandle Register<T>(T messageFilter)
-                where T : IMessageFilter
-            {
-                var handle = Marshal.GetComInterfaceForObject<T, IMessageFilter>(messageFilter);
-                return new MessageFilterSafeHandle(handle);
-            }
-
-            protected override bool ReleaseHandle()
-            {
-                if (CoRegisterMessageFilter(_oldFilter, out _) == VSConstants.S_OK)
-                {
-                    Marshal.Release(handle);
-                }
-
-                return true;
-            }
-        }
     }
 }

src/VisualStudio/IntegrationTest/TestUtilities/Harness/MessageFilter.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using IMessageFilter = Microsoft.VisualStudio.OLE.Interop.IMessageFilter;
+using INTERFACEINFO = Microsoft.VisualStudio.OLE.Interop.INTERFACEINFO;
+using PENDINGMSG = Microsoft.VisualStudio.OLE.Interop.PENDINGMSG;
+using SERVERCALL = Microsoft.VisualStudio.OLE.Interop.SERVERCALL;
+
+namespace Microsoft.VisualStudio.IntegrationTest.Utilities.Harness
+{
+    public class MessageFilter : IMessageFilter, IDisposable
+    {
+        protected const uint CancelCall = ~0U;
+
+        private readonly MessageFilterSafeHandle _messageFilterRegistration;
+        private readonly TimeSpan _timeout;
+        private readonly TimeSpan _retryDelay;
+
+        public MessageFilter()
+            : this(timeout: TimeSpan.FromSeconds(60), retryDelay: TimeSpan.FromMilliseconds(150))
+        {
+        }
+
+        public MessageFilter(TimeSpan timeout, TimeSpan retryDelay)
+        {
+            _timeout = timeout;
+            _retryDelay = retryDelay;
+            _messageFilterRegistration = MessageFilterSafeHandle.Register(this);
+        }
+
+        public virtual uint HandleInComingCall(uint dwCallType, IntPtr htaskCaller, uint dwTickCount, INTERFACEINFO[] lpInterfaceInfo)
+        {
+            return (uint)SERVERCALL.SERVERCALL_ISHANDLED;
+        }
+
+        public virtual uint RetryRejectedCall(IntPtr htaskCallee, uint dwTickCount, uint dwRejectType)
+        {
+            if ((SERVERCALL)dwRejectType != SERVERCALL.SERVERCALL_RETRYLATER
+                && (SERVERCALL)dwRejectType != SERVERCALL.SERVERCALL_REJECTED)
+            {
+                return CancelCall;
+            }
+
+            if (dwTickCount >= _timeout.TotalMilliseconds)
+            {
+                return CancelCall;
+            }
+
+            return (uint)_retryDelay.TotalMilliseconds;
+        }
+
+        public virtual uint MessagePending(IntPtr htaskCallee, uint dwTickCount, uint dwPendingType)
+        {
+            return (uint)PENDINGMSG.PENDINGMSG_WAITDEFPROCESS;
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _messageFilterRegistration.Dispose();
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+    }
+}

src/VisualStudio/IntegrationTest/TestUtilities/Harness/MessageFilterSafeHandle.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Runtime.InteropServices;
+using Microsoft.Win32.SafeHandles;
+using IMessageFilter = Microsoft.VisualStudio.OLE.Interop.IMessageFilter;
+
+namespace Microsoft.VisualStudio.IntegrationTest.Utilities.Harness
+{
+    internal sealed class MessageFilterSafeHandle : SafeHandleMinusOneIsInvalid
+    {
+        private readonly IntPtr _oldFilter;
+
+        private MessageFilterSafeHandle(IntPtr handle)
+            : base(true)
+        {
+            SetHandle(handle);
+
+            try
+            {
+                if (CoRegisterMessageFilter(handle, out _oldFilter) != VSConstants.S_OK)
+                {
+                    throw new InvalidOperationException("Failed to register a new message filter");
+                }
+            }
+            catch
+            {
+                SetHandleAsInvalid();
+                throw;
+            }
+        }
+
+        [DllImport("ole32", SetLastError = true)]
+        private static extern int CoRegisterMessageFilter(IntPtr messageFilter, out IntPtr oldMessageFilter);
+
+        public static MessageFilterSafeHandle Register<T>(T messageFilter)
+            where T : IMessageFilter
+        {
+            var handle = Marshal.GetComInterfaceForObject<T, IMessageFilter>(messageFilter);
+            return new MessageFilterSafeHandle(handle);
+        }
+
+        protected override bool ReleaseHandle()
+        {
+            if (CoRegisterMessageFilter(_oldFilter, out _) == VSConstants.S_OK)
+            {
+                Marshal.Release(handle);
+            }
+
+            return true;
+        }
+    }
+}