@Test
 public void testClearPrimaryPrerequisite() throws Exception {
   IGenericTrait unwanted = new ValuedTraitType(AbilityType.Athletics, 4);
   data.setPrimaryPrerequisite(unwanted);
   data.clearPrimaryPrerequisite();
   assertEquals(0, data.getPrerequisites().length);
   assertNull(data.getPrimaryTraitType());
 }