Functional test for cherry-pick -> restore corruption

GVFS/GVFS.FunctionalTests/Tests/GitCommands/CorruptionReproTests.cs

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+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using GVFS.Common;
+using GVFS.FunctionalTests.Properties;
+using GVFS.FunctionalTests.Tests.EnlistmentPerTestCase;
+using NUnit.Framework;
+
+namespace GVFS.FunctionalTests.Tests.GitCommands
+{
+    /// <summary>
+    /// This class is used to reproduce corruption scenarios in the GVFS virtual projection.
+    /// </summary>
+    [Category(Categories.GitCommands)]
+    [TestFixtureSource(typeof(GitRepoTests), nameof(GitRepoTests.ValidateWorkingTree))]
+    public class CorruptionReproTests : GitRepoTests
+    {
+        public CorruptionReproTests(Settings.ValidateWorkingTreeMode validateWorkingTree)
+            : base(enlistmentPerTest: true, validateWorkingTree: validateWorkingTree)
+        {
+        }
+
+        [TestCase]
+        public void ReproCherryPickRestoreCorruption()
+        {
+            // Based on FunctionalTests/20170206_Conflict_Source
+            const string CherryPickCommit = "51d15f7584e81d59d44c1511ce17d7c493903390";
+            const string StartingCommit = "db95d631e379d366d26d899523f8136a77441914";            
+
+            this.ControlGitRepo.Fetch(StartingCommit);
+            this.ControlGitRepo.Fetch(CherryPickCommit);
+
+            this.ValidateGitCommand($"checkout -b FunctionalTests/CherryPickRestoreCorruptionRepro {StartingCommit}");
+
+            // Cherry-pick a variety of changes (adds, deletes, modifications) but don't commit.
+            // This will leave the repo in a state where the changes are staged (in the index).
+            this.ValidateGitCommand($"cherry-pick -n {CherryPickCommit}");
+
+            // Restore --staged should remove the changes from the index but leave them as-is (ie changed)
+            // in the working directory.
+            // As of VFSForGit 1.0.25169.1 and git 2.50.1.vfs.0.0, the working directory is as-is (still changed,
+            // as expected), but the index shows modified/deleted files as unchanged (ie completely reverted)
+            // and added files as still staged.
+            this.ValidateGitCommand("restore --staged .");
+            this.FilesShouldMatchCheckoutOfSourceBranch();
+        }
+    }
+}