GroupByTests.cs: In GroupByTwoFieldsWhereOneOfThemIsTooDeep() we get a NullReferenceException from inside the result transformer lambda when running on .Net 4. Perhaps there is something deep in .Net framework that differs between 2.0 and 4.0?. In any case, casting to (int?) already in the group expression resolves this, which seems like a reasonable fix given that an employee may indeed lack a superior.

Author: oskarb

src/NHibernate.Test/Linq/ByMethod/GroupByTests.cs

@@ -228,12 +228,12 @@ public void GroupByTwoFieldsWhereOneOfThemIsTooDeep()
 		{
 			var query = (from ol in db.OrderLines
 						 let superior = ol.Order.Employee.Superior
-						 group ol by new {ol.Order.OrderId, SuperiorId = superior.EmployeeId}
+						 group ol by new { ol.Order.OrderId, SuperiorId = (int?)superior.EmployeeId }
 						 into temp
 						 select new
 									{
 										OrderId = (int?) temp.Key.OrderId,
-										SuperiorId = (int?) temp.Key.SuperiorId,
+										SuperiorId = temp.Key.SuperiorId,
 										Count = temp.Count(),
 									}).ToList();