private int[] makeValidSelected() {
    int[] selected = new int[512];
    for (int i=0; i < selected.length; i++){
      selected[i] = i*2;
    }
    return selected;
  }
Test creation and manipulation of MutableFilterContext and FilterContext.
ql/src/test/org/apache/hadoop/hive/ql/io/filter/TestFilterContext.java