@Test
public void testGenericUDF() {
// create a syntax tree for a function call 'myisnull(col0, "UNKNOWN")'
ExprNodeGenericFuncDesc funcDesc;
GenericUDF genericUDF = new GenericUDFIsNull();
TypeInfo typeInfoStr = TypeInfoFactory.stringTypeInfo;
List<ExprNodeDesc> children = new ArrayList<ExprNodeDesc>();
children.add(new ExprNodeColumnDesc(typeInfoStr, "col0", "tablename", false));
children.add(new ExprNodeConstantDesc(typeInfoStr, "UNKNOWN"));