### Question:
DepthTreeIterator implements TreeIterator<T> { @Override public boolean hasNext() { return iterator.hasNext() || selfHasNext() || childrenHasNext(); } DepthTreeIterator(@Nonnull TreeNode<T> root);   DepthTreeIterator(@Nonnull Tree<T> tree);   DepthTreeIterator(@Nonnull Collection<? extends TreeNode<T>> nodes); private  DepthTreeIterator(@Nonnull Collection<? extends TreeNode<T>> nodes, int depth); private  DepthTreeIterator(@Nonnull Iterator<? extends TreeNode<T>> iterator, int depth); @Override boolean hasNext(); @Override TreeNode<T> next(); @Override int getDepth(); @Override void remove();  }### Answer:
@Test public void testHasNext() throws Exception { LinkedTreeTest.createMockTree(); }