ExpressionSessionLeakTest - mark as KnownBug and refactor to use using statement.

Author: hazzik

src/NHibernate.Test/Linq/ExpressionSessionLeakTest.cs

@@ -8,32 +8,30 @@ namespace NHibernate.Test.Linq
 {
 	public class ExpressionSessionLeakTest : LinqTestCase
 	{
-		[Test]
-		[Ignore("Not fixed yet. NH-3579")]
+		[Test, KnownBug("NH-3579")]
 		public void SessionGetsCollected()
 		{
 			var reference = DoLinqInSeparateSession();
 
 			GC.Collect();
 
-			Assert.Null(reference.Target);
+			Assert.That(reference.IsAlive, Is.False);
 		}
 
-
 		private WeakReference DoLinqInSeparateSession()
 		{
-			var leakTest = session.SessionFactory.OpenSession();
-
-			// It appears linq expressions will (or might) contain a reference to the
-			// IQueryable. At time of writing, linq expressions are helt within NhLinqExpression,
-			// which in turn will be held in the query plan cache. Since the IQueryable will
-			// be an NhQueryable, which holds a reference to the SessionImpl instance,
-			// we will be leaking session instances.
-
-			var query = leakTest.Query<Customer>().FirstOrDefault(t => t.CustomerId != "");
-			leakTest.Dispose();
-
-			return new WeakReference(leakTest, false);
+			using (var leakTest = session.SessionFactory.OpenSession())
+			{
+				// It appears linq expressions will (or might) contain a reference to the
+				// IQueryable. At time of writing, linq expressions are helt within NhLinqExpression,
+				// which in turn will be held in the query plan cache. Since the IQueryable will
+				// be an NhQueryable, which holds a reference to the SessionImpl instance,
+				// we will be leaking session instances.
+
+				var query = leakTest.Query<Customer>().FirstOrDefault(t => t.CustomerId != "");
+
+				return new WeakReference(leakTest, false);
+			}
 		}
 	}
 }