@Test( expected = UnsupportedOperationException.class )
public void shouldReturnImmutableIteratorOfChildren() {

    parent = new AstNode("parent");
    new AstNode(parent, "childA");
    new AstNode(parent, "childB");
    new AstNode(parent, "childC");
    Iterator<AstNode> iter = parent.iterator();
    iter.next();
    iter.remove();
}