Renaming entities with RavenDb patching API

gistfile1.cs

using System.Linq;
using System.Threading;
using Raven.Abstractions.Data;
using Raven.Abstractions.Indexing;
using Raven.Client;
using Raven.Client.Embedded;
using Raven.Json.Linq;
using Xunit;

namespace RavenDbPatching.StringIdPatching {

	public class StringIdPatchingTests {
		[Fact]
		public void CanRenameEntityWithStringId() {
			var documentStore = new EmbeddableDocumentStore() { RunInMemory = true }.Initialize();
			createDocumentsByEntityNameIndex(documentStore as EmbeddableDocumentStore);
			
			var group = new Group {
				Name = "Cars"
			};

			using (var session = documentStore.OpenSession()) {
				session.Store(group);
				session.SaveChanges();
			}

			while (documentStore.DatabaseCommands.GetStatistics().StaleIndexes.Length != 0) {
				Thread.Sleep(10);
			}

			new Migrations(documentStore).Migrate();

			while (documentStore.DatabaseCommands.GetStatistics().StaleIndexes.Length != 0) {
				Thread.Sleep(10);
			}

			using (var session = documentStore.OpenSession()) {
				var category = session.Query<Category>().FirstOrDefault();
				Assert.NotNull(category); // fails
			}
		}

		private void createDocumentsByEntityNameIndex(EmbeddableDocumentStore store) {
			var database = store.DocumentDatabase;
			if (database.GetIndexDefinition("Raven/DocumentsByEntityName") == null) {
				database.PutIndex("Raven/DocumentsByEntityName", new IndexDefinition {
					Map =
						@"from doc in docs 
let Tag = doc[""@metadata""][""Raven-Entity-Name""]
select new { Tag, LastModified = (DateTime)doc[""@metadata""][""Last-Modified""] };",
					Indexes =
						{
							{"Tag", FieldIndexing.NotAnalyzed},
						},
					Stores =
						{
							{"Tag", FieldStorage.No},
							{"LastModified", FieldStorage.No}
						}
				});
			}
		}
	}

	public class Group {
		public string Id { get; set; }
		public string Name { get; set; }
	}

	public class Category {
		public string Id { get; set; }
		public string Name { get; set; }
	}

	public class Migrations {
		readonly IDocumentStore _documentStore;

		public Migrations(IDocumentStore documentStore) {
			_documentStore = documentStore;
		}

		public void Migrate() {
			_documentStore.DatabaseCommands.UpdateByIndex(
				"Raven/DocumentsByEntityName",
				new IndexQuery {
					Query = "Tag:Group"
				},
				new[]
				{

					new PatchRequest
						{
							Type = PatchCommandType.Modify,
							Name = "@metadata",
							Nested = new[]
								{
									new PatchRequest
										{
											Type = PatchCommandType.Set,
											Name = "Raven-Entity-Name",
											Value = new RavenJValue("Category")
										}
										,
									new PatchRequest
										{
											Type = PatchCommandType.Set,
											Name = "Raven-Clr-Type",
											Value = new RavenJValue("RavenDbPatching.StringIdPatching.Category, RavenDbPatching")
										}
										
								}
						}
						
				}, false);
		}
	}
}