@Test
public void testDuplicateColumns() {
AbstractExpression expression = new NullValueExpression();
String columnName = "TABLEA.A_ID";
SortOrder sortOrder = SortOrder.kUnsorted;
Storage storage = Storage.kTemporary;
PlanColumn col0 = context.getPlanColumn(expression, columnName, sortOrder, storage);
assertNotNull(col0);
// System.err.println(col0 + " ==> " + col0.hashCode());