### Question:
ZkTreeModel extends DefaultTreeModel<E> { @Override public TreeNode<E> getChild(int... path) { return super.getChild(path); } ZkTreeModel(@Nonnull TreeNode<E> root); TreeNode<E> find(@Nonnull E data); @Override TreeNode<E> getChild(int... path); E getChildData(int... path); E getSelectedData(@Nonnegative int depth); TreeNode<E> removeSelected(); TreeNode<E> removeChild(int... path); ZkTreeNode<E> addExpandableNode(E data, int... parentNodePath); void dropNodeBefore(TreeNode<E> node, TreeNode<E> target); void dropNodeIn(TreeNode<E> node, TreeNode<E> target); void setSelectedNode(TreeNode<E> node);  }### Answer:
@Test public void testGetChild() throws Exception { assertSame(sut.getChild(1, 0), sut.getRoot().getChildAt(1).getChildAt(0)); }
@Test public void testGetChild_withNoSuchPathExisting() throws Exception { assertNull(sut.getChild(5)); }
@Test public void testGetChild_withEmptyPath() throws Exception { assertSame(sut.getChild(), sut.getRoot()); }