### Question:
NodeToElementTreeWalker implements TreeWalker<N> { @Override public void onStarted() { delegateTreeWalker.onStarted(); } NodeToElementTreeWalker(TreeWalker<E> delegateTreeWalker); @Override void onStarted(); @Override void onNode(N node); @Override void onNodeChildrenStarted(N node); @Override void onNodeChildrenRemaining(N node); @Override void onNodeChildrenCompleted(N node); @Override void onNodeNoChildren(N node); @Override void onCompleted();  }### Answer:
@Test public void onStarted() throws Exception { final NodeToElementTreeWalker<String, MutableSettableStructuredNode<String>> elementWalker = new NodeToElementTreeWalker<>(walker); elementWalker.onStarted(); Mockito.verify(walker).onStarted(); }