increase test coverage, case of null -> Option[UUID]

Author: max-l

src/test/scala/org/squeryl/test/UuidTests.scala

@@ -77,6 +77,12 @@ abstract class UuidTests extends SchemaTester with RunTestsInsideTransaction{
 
     uuidWithOption.lookup(testObject.id).get.optionalUuid should equal(Some(uuid))
 
+    update(uuidWithOption)(p =>
+      where(p.id === testObject.id)
+      set(p.optionalUuid := None)
+    )
+    
+    uuidWithOption.lookup(testObject.id).get.optionalUuid should equal(None)    
   }
 
   test("UuidAsId") {