### Question:
RootNode extends BasicTreeNode { @Override public void setSibling(TreeNode sibling) { throw new IllegalAccessError("This is the root node"); }  @Override char getNodeValue(); @Override boolean isRoot(); @Override boolean hasInterestIn(char value, SearchContext context); @Override void setSibling(TreeNode sibling); @Override void setParent(TreeNode parent);  }### Answer:
@Test(expectedExceptions = IllegalAccessError.class) public void setSiblingDisabled() { rootTreeNode.setSibling(mock(TreeNode.class)); }