### Question:
IndexResultSet extends TreeSet<IndexItem> { public boolean contains(String uri) {return uriToItem.containsKey(uri);}  boolean contains(String uri); boolean contains(IndexItem item); @Override boolean contains(Object o); IndexItem get(String uri); IndexItem get(IndexItem item); @Override boolean add(IndexItem item); @Synchronized boolean remove(IndexItem item); @Override @Synchronized boolean remove(Object o); @Override boolean removeAll(Collection<?> c); @Override void clear(); @Override boolean addAll(Collection<? extends IndexItem> c); boolean retainAll(Collection<?> c); @Override Iterator<IndexItem> iterator();  }### Answer:
@Test public void testContainsString() { IndexResultSet test = testSet(); assertTrue(test.contains(LEIPZIG_URI)); assertFalse(test.contains(BERLIN_URI)); }
@Test public void testContainsIndexItem() { IndexResultSet test = testSet(); assertTrue(test.contains(leipzig2)); assertFalse(test.contains(berlin)); }
@Test public void testContainsObject() { IndexResultSet test = testSet(); assertTrue(test.contains((Object)leipzig2)); assertFalse(test.contains((Object)berlin)); assertTrue(test.contains((Object)LEIPZIG_URI)); assertFalse(test.contains((Object)BERLIN_URI)); }