OutlinePageDestinations { public void addPage(Integer page, String title) { if (page == null) { throw new IllegalArgumentException("Unable to add a null page to the destinations."); } destinations.put(page, title); }  void addPage(Integer page, String title); Set<Integer> getPages(); String getTitle(Integer page);  }
@Test(expected = IllegalArgumentException.class) public void testAddNull() { OutlinePageDestinations victim = new OutlinePageDestinations(); victim.addPage(null, "Title1"); }