From 9d7392865279b10cf10c6061ca25569bd22e88d3 Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Mon, 23 Nov 2020 10:38:45 +0100
Subject: [PATCH] Fix `ancestors` not working when in `root`

Closes rehypejs/rehype-sanitize#8.
---
 lib/index.js | 2 +-
 test.js      | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/index.js b/lib/index.js
index 1665e11..b9e8cad 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -249,7 +249,7 @@ function handleTagName(schema, tagName, node, stack) {
   // Some nodes can break out of their context if they don’t have a certain
   // ancestor.
   if (own.call(schema.ancestors, name)) {
-    while (++index <= schema.ancestors[name].length) {
+    while (++index < schema.ancestors[name].length) {
       if (stack.indexOf(schema.ancestors[name][index]) > -1) {
         return name
       }
diff --git a/test.js b/test.js
index 749fe75..9255452 100644
--- a/test.js
+++ b/test.js
@@ -647,6 +647,15 @@ test('sanitize()', function (t) {
       'should allow known properties'
     )
 
+    t.deepEqual(
+      sanitize(u('root', [h('div', h('li', 'text'))]), {
+        tagNames: ['div', 'ul', 'li'],
+        ancestors: {li: ['ul']}
+      }),
+      u('root', [h('div', 'text')]),
+      'should support `ancestors` to enforce certain ancestors in a `root` (rehypejs/rehype-sanitize#8)'
+    )
+
     t.end()
   })