public void testRemoveNotExists() throws Exception {
   try {
     ConstraintSet set = new ConstraintSet(ConstraintOp.OR);
     set.addConstraint(sc1);
     set.removeConstraint(sc2);
     fail("Expected IllegalArgumentExcepion");
   } catch (IllegalArgumentException e) {
   }
 }
  public void testRemoveConstrint() {
    ConstraintSet set = new ConstraintSet(ConstraintOp.AND);
    set.addConstraint(sc1);
    set.addConstraint(sc2);
    set.removeConstraint(sc1);

    LinkedHashSet test = new LinkedHashSet();
    test.add(sc2);

    assertEquals(test, set.getConstraints());
  }