@Test(expected = IllegalArgumentException.class)
 public void testCannotRemovePrimaryPrerequisite() throws Exception {
   IGenericTrait expected = new ValuedTraitType(AbilityType.Awareness, 4);
   data.setPrimaryPrerequisite(expected);
   data.removePrerequisite(expected);
   assertEquals(1, data.getPrerequisites().length);
   assertTrue(ArrayUtilities.containsValue(data.getPrerequisites(), expected));
 }
 @Test
 public void testRemovePrerequisite() throws Exception {
   IGenericTrait unwanted = new ValuedTraitType(AbilityType.Athletics, 4);
   data.addPrerequisite(unwanted);
   data.removePrerequisite(unwanted);
   assertEquals(0, data.getPrerequisites().length);
   assertFalse(ArrayUtilities.containsValue(data.getPrerequisites(), unwanted));
 }