public virtual void TestJoinMultiKey()
{
var list = (
from c in db.Customers
where c.CustomerID == "ALFKI"
join o in db.Orders on new { a = c.CustomerID, b = c.CustomerID } equals new { a = o.CustomerID, b = o.CustomerID }
select new { c, o }
).ToList();
AssertValue(6, list.Count);
}