Feature Complete

- Add remaining test scenarios
- Refactor implementation
- Add gitignore entry for optimization profiles

test/dotnet.Tests/TestCommandExtensions.cs

@@ -0,0 +1,31 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. 
+// Licensed under the MIT license. See LICENSE file in the project root for full license information. 
+
+using Microsoft.DotNet.Cli.Utils;
+using Microsoft.DotNet.Tools.Test.Utilities;
+using Microsoft.Extensions.PlatformAbstractions;
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+using Xunit;
+using Xunit.Abstractions;
+using FluentAssertions;
+
+namespace Microsoft.DotNet.Tests
+{
+    public static class TestCommandExtensions
+    {
+        public static TestCommand WithUserProfileRoot(this TestCommand testCommand, string path)
+        {
+            var userProfileEnvironmentVariableName = GetUserProfileEnvironmentVariableName();
+            return testCommand.WithEnvironmentVariable(userProfileEnvironmentVariableName, path);
+        }
+        
+        private static string GetUserProfileEnvironmentVariableName()
+        {
+            return RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+                ? "LocalAppData"
+                : "HOME";
+        }
+    }
+}