Implement missing helper types

Author: sharwell

Tvl.VisualStudio.MouseFastScroll.IntegrationTests/Threading/ExceptionUtilities.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE.txt in the project root for license information.
+
+namespace Tvl.VisualStudio.MouseFastScroll.IntegrationTests.Threading
+{
+    using System;
+
+    internal static class ExceptionUtilities
+    {
+        internal static Exception Unreachable
+            => new InvalidOperationException("This program location is thought to be unreachable.");
+    }
+}

Tvl.VisualStudio.MouseFastScroll.IntegrationTests/Threading/ExecutionCondition.cs

@@ -0,0 +1,12 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE.txt in the project root for license information.
+
+namespace Tvl.VisualStudio.MouseFastScroll.IntegrationTests.Threading
+{
+    public abstract class ExecutionCondition
+    {
+        public abstract bool ShouldSkip { get; }
+
+        public abstract string SkipReason { get; }
+    }
+}