### Question:
ZkTreeModel extends DefaultTreeModel<E> { public E getChildData(int... path) { TreeNode<E> child = getChild(path); if (child == null) { return null; } return child.getData(); } 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 testGetChildData() throws Exception { assertSame(sut.getChildData(1, 0), sut.getRoot().getChildAt(1).getChildAt(0).getData()); }
@Test public void testGetChildData_withNoSuchPathExisting() throws Exception { assertNull(sut.getChildData(5)); }