instead of returning null.
+ assert_eq!(result, serde_json::json!([["A", "C"], ["A"]]));
+ }
+
+ /// Issue #462: a backward walk must retrace a forward walk exactly, and stop
+ /// at the root without ever returning it.
+ #[test]
+ fn previous_node_retraces_a_full_forward_walk() {
+ let mut rt = setup_runtime(
+ r#""#,
+ );
+ rt.run_page_init();
+ let result = rt
+ .evaluate(
+ r#"
+ const root = document.getElementById('root');
+ const w = document.createTreeWalker(root, NodeFilter.SHOW_ELEMENT);
+ const forward = [];
+ let node;
+ while ((node = w.nextNode())) forward.push(node.tagName);
+ const backward = [];
+ while ((node = w.previousNode())) backward.push(node.tagName);
+ backward.reverse();
+ // previousNode never yields root, and never yields the node the
+ // forward walk ended on, so compare against forward minus its last.
+ // A failed traversal leaves currentNode untouched (DOM 6.1), so
+ // it stays on the last node previousNode did return.
+ return [forward, backward, w.currentNode.tagName];
+ "#,
+ )
+ .unwrap();
+ assert_eq!(
+ result,
+ serde_json::json!([
+ ["SECTION", "P", "SPAN", "A", "B"],
+ ["SECTION", "P", "SPAN", "A"],
+ "SECTION"
+ ])
+ );
+ }
+
+ /// Issue #462: FILTER_REJECT prunes a subtree in the backward direction too
+ /// — the descent into a rejected node's last children must stop.
+ #[test]
+ fn previous_node_honours_filter_reject_subtree_pruning() {
+ let mut rt = setup_runtime(
+ r#""#,
+ );
+ rt.run_page_init();
+ let result = rt
+ .evaluate(
+ r#"
+ const root = document.getElementById('root');
+ const w = document.createTreeWalker(root, NodeFilter.SHOW_ELEMENT, {
+ acceptNode(node) {
+ return node.tagName === 'SECTION'
+ ? NodeFilter.FILTER_REJECT
+ : NodeFilter.FILTER_ACCEPT;
+ }
+ });
+ while (w.nextNode()) { /* advance to the last accepted node */ }
+ const backward = [];
+ let node;
+ while ((node = w.previousNode())) backward.push(node.tagName);
+ return backward;
+ "#,
+ )
+ .unwrap();
+ // lives inside the rejected