--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/UnitTests/Linq/UserTests/FirstOrDefaultNullReferenceExceptionTest.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using BLToolkit.DataAccess;
+using BLToolkit.Mapping;
+
+using NUnit.Framework;
+
+namespace Data.Linq.UserTests
+{
+	[TestFixture]
+	public class FirstOrDefaultNullReferenceExceptionTest : TestBase
+	{
+		[TableName("GrandChild")]
+		class Table1
+		{
+			public int ChildID;
+		}
+
+		[TableName("Child")]
+		class Table2
+		{
+			public int ChildID;
+			public int ParentID;
+
+			[Association(ThisKey = "ChildID", OtherKey = "ChildID", CanBeNull = true)]
+			public List<Table1> GrandChildren { get; set; }
+		}
+
+		[TableName("Parent")]
+		class Table3
+		{
+			public int ParentID { get; set; }
+
+			[Association(ThisKey = "ParentID", OtherKey = "ParentID", CanBeNull = true)]
+			public List<Table2> Children { get; set; }
+		}
+
+		[Test]
+		public void Test()
+		{
+			using (var db = new TestDbManager())
+			{
+				/*
+				var query =
+					from t3 in db.Parent
+					//let t1 = t3.Children.SelectMany(x => x.GrandChildren)
+					//let t2 = t3.Table2s.SelectMany(x => x.Table1s)
+					select new
+					{
+						//c2 = t1.Count(),
+						c1 = t3.Children.SelectMany(x => x.GrandChildren),
+					};
+				 */
+
+				var query =
+					from t3 in db.GetTable<Table3>()
+					let t1 = t3.Children.SelectMany(x => x.GrandChildren)
+					//let t2 = t3.Table2s.SelectMany(x => x.Table1s)
+					select new
+					{
+						c2 = t1.Count(),
+						c1 = t3.Children.SelectMany(x => x.GrandChildren).Count(),
+					};
+
+				query.FirstOrDefault(p => p.c1 > 10);
+			}
+		}
+	}
+}