 			}
 
 			it("should fetch an existing object") {
+				let json = ["uniqueValue":"unique id", "username": "Fons"]
+
 				let entity = try! CoreDataEntity(json: json, managedObjectContext: coreDataController.managedObjectContext)
 
 				let sameEntity = try! CoreDataEntity.lookupExistingObjectFromJSON(json, managedObjectContext: coreDataController.managedObjectContext)

				expect(allEntities).to(haveCount(1))
			}

			it("should not throw when no instance is found", closure: { 
				let entity = try! CoreDataEntity.lookupExistingObjectFromJSON(json, managedObjectContext: coreDataController.managedObjectContext)
				expect(entity).to(beNil())
			})

			it("should throw when more then one instance is found", closure: {
				let _ = try! CoreDataEntity(json: ["":""], managedObjectContext: coreDataController.managedObjectContext)
				let _ = try! CoreDataEntity(json: ["":""], managedObjectContext: coreDataController.managedObjectContext)
				expect(expression: { try CoreDataEntity.lookupExistingObjectFromJSON(json, managedObjectContext: coreDataController.managedObjectContext)}).to(throwError{ (error) in
					switch error {
					case MapError.EnityShouldBeUniqueForJSON(json: _, typeName: _):

				coreDataController.managedObjectContext.reset()
			})


			it("Create instanse with username") {
				let entity = try! CoreDataEntity(json: ["username": "Fons"], managedObjectContext: coreDataController.managedObjectContext)
