### Question:
RadixTreeImpl implements RadixTree<T>, Formattable { public boolean contains(String key) { Visitor<T, Boolean> visitor = new VisitorImpl<T,Boolean>(Boolean.FALSE) { public void visit(String key, RadixTreeNode<T> parent, RadixTreeNode<T> node) { result = node.isReal(); } }; visit(key, visitor); return visitor.getResult().booleanValue(); } RadixTreeImpl(); T find(String key); boolean delete(String key); void insert(String key, T value); ArrayList<T> searchPrefix(String key, int recordLimit); boolean contains(String key); void visit(String key, Visitor<T, R> visitor); long getSize(); @Deprecated void display(); @Override void formatTo(Formatter formatter, int flags, int width, int precision); String complete(String prefix);  }### Answer:
@Test public void testDoesntContainNonexistantNode() { assertFalse(trie.contains("apple")); }