adds another test to ensure the cache expiry is working

src/Umbraco.Core/Persistence/PetaPoco.cs

@@ -1704,13 +1704,16 @@ namespace Umbraco.Core.Persistence
             }
 
             static readonly ObjectCache ObjectCache = new MemoryCache("NPoco");
+            
         }
 
         public class PocoData
         {
             //USE ONLY FOR TESTING
             internal static bool UseLongKeys = false;
-
+            //USE ONLY FOR TESTING - default is one hr
+            internal static int SlidingExpirationSeconds = 3600;
+            
 			public static PocoData ForObject(object o, string primaryKeyName)
 			{
 				var t = o.GetType();
@@ -2078,7 +2081,7 @@ namespace Umbraco.Core.Persistence
                 {
                     //sliding expiration of 1 hr, if the same key isn't used in this 
                     // timeframe it will be removed from the cache
-                    SlidingExpiration = new TimeSpan(1,0,0)
+                    SlidingExpiration = new TimeSpan(0, 0, SlidingExpirationSeconds)
                 });
                 return (value ?? newValue).Value; // Lazy<T> handles the locking itself
 
@@ -2170,7 +2173,7 @@ namespace Umbraco.Core.Persistence
 			public TableInfo TableInfo { get; private set; }
 			public Dictionary<string, PocoColumn> Columns { get; private set; }
             static System.Threading.ReaderWriterLockSlim InnerLock = new System.Threading.ReaderWriterLockSlim();
-
+            
             /// <summary>
             /// Returns a report of the current cache being utilized by PetaPoco
             /// </summary>

src/Umbraco.Core/Persistence/Repositories/TagRepository.cs

@@ -163,6 +163,8 @@ namespace Umbraco.Core.Persistence.Repositories
 
         //TODO: Consider caching implications.
 
+        //TODO: We need to add lookups for parentId or path! (i.e. get content in tag group that are descendants of x)
+
 
         public IEnumerable<TaggedEntity> GetTaggedEntitiesByTagGroup(TaggableObjectTypes objectType, string tagGroup)
         {

src/Umbraco.Tests/Persistence/PetaPocoExtensionsTest.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text.RegularExpressions;
+using System.Threading;
 using NUnit.Framework;
 using Umbraco.Core;
 using Umbraco.Core.Models;
@@ -73,6 +74,29 @@ namespace Umbraco.Tests.Persistence
             Assert.AreEqual(1, totalKeys.Count());
         }
 
+        [Test]
+        public void Verify_Memory_Expires()
+        {
+            Database.PocoData.SlidingExpirationSeconds = 2;
+
+            var managedCache = new Database.ManagedCache();
+
+            int id1, id2, id3;
+            string alias;
+            CreateStuff(out id1, out id2, out id3, out alias);
+            QueryStuff(id1, id2, id3, alias);
+
+            var count1 = managedCache.GetCache().GetCount();
+            Console.WriteLine("Keys = " + count1);
+            Assert.Greater(count1, 0);
+            
+            Thread.Sleep(10000);
+
+            var count2 = managedCache.GetCache().GetCount();
+            Console.WriteLine("Keys = " + count2);
+            Assert.Less(count2, count1);
+        }
+
         private void QueryStuff(int id1, int id2, int id3, string alias1)
         {
             var contentService = ServiceContext.ContentService;