Salesforce CategoryNode sObject in Apex Unit Tests

In Salesforce,DML operation is not allowed on CategoryNode sObject,even in Unit Test. Although the 《Force.com Apex Code Developer’s Guide》 does not mention it clearly,that CategoryNode object can be accessed in Apex Tests, we have to prepare CategoryNode data first in Setup interface.by clicking Customize > Solution > Solution Categories.

The following is the sample code for CategoryNode and CategoryData sObject testing ,and it works for me.


Reference : CategoryNode API Reference  and   CategoryData API Reference