Fix tests and fix algorithm

Co-authored-by: Jon Surrell <sirreal@users.noreply.github.com>

Author: dmsnell

src/wp-includes/html-api/class-wp-html-processor.php

@@ -764,15 +764,21 @@ private function step_in_body() {
 			case '+LI':
 				$this->state->frameset_ok = false;
 				$node                     = $this->state->stack_of_open_elements->current_node();
+				$is_li                    = 'LI' === $tag_name;
 
 				in_body_list_loop:
-				if ( $tag_name === $node->node_name ) {
-					$this->generate_implied_end_tags();
-					if ( $tag_name !== $this->state->stack_of_open_elements->current_node()->node_name ) {
+				/*
+				 * The logic for LI and DT/DD is the same except for one point: LI elements _only_
+				 * close other LI elements, but a DT or DD element closes _any_ open DT or DD element.
+				 */
+				if ( $is_li ? 'LI' === $node->node_name : ( 'DD' === $node->node_name || 'DT' === $node->node_name ) ) {
+					$node_name = $is_li ? 'LI' : $node->node_name;
+					$this->generate_implied_end_tags( $node_name );
+					if ( $node_name !== $this->state->stack_of_open_elements->current_node()->node_name ) {
 						// @TODO: Indicate a parse error once it's possible. This error does not impact the logic here.
 					}
 
-					$this->state->stack_of_open_elements->pop_until( $tag_name );
+					$this->state->stack_of_open_elements->pop_until( $node_name );
 					goto in_body_list_done;
 				}
 

tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php

@@ -363,10 +363,10 @@ public function data_html_target_with_breadcrumbs() {
 			'LI after unclosed LI'                  => array( '<li>one<li>two<li target>three', array( 'HTML', 'BODY', 'LI' ), 3 ),
 			'LI in UL in LI'                        => array( '<ul><li>one<ul><li target>two', array( 'HTML', 'BODY', 'UL', 'LI', 'UL', 'LI' ), 1 ),
 
-			'DD and DT mutually close, LI self-closes (dt 2)' => array( '<dd><dd><dt><dt target><dd><li><li>', array( 'HTML', 'BODY', 'DT' ), 1 ),
-			'DD and DT mutually close, LI self-closes (dd 3)' => array( '<dd><dd><dt><dt><dd target><li><li>', array( 'HTML', 'BODY', 'DD' ), 1 ),
+			'DD and DT mutually close, LI self-closes (dt 2)' => array( '<dd><dd><dt><dt target><dd><li><li>', array( 'HTML', 'BODY', 'DT' ), 2 ),
+			'DD and DT mutually close, LI self-closes (dd 3)' => array( '<dd><dd><dt><dt><dd target><li><li>', array( 'HTML', 'BODY', 'DD' ), 3 ),
 			'DD and DT mutually close, LI self-closes (li 1)' => array( '<dd><dd><dt><dt><dd><li target><li>', array( 'HTML', 'BODY', 'DD', 'LI' ), 1 ),
-			'DD and DT mutually close, LI self-closes (li 2)' => array( '<dd><dd><dt><dt><dd><li><li target>', array( 'HTML', 'BODY', 'DD', 'LI' ), 1 ),
+			'DD and DT mutually close, LI self-closes (li 2)' => array( '<dd><dd><dt><dt><dd><li><li target>', array( 'HTML', 'BODY', 'DD', 'LI' ), 2 ),
 		);
 	}
 

tests/phpunit/tests/html-api/wpHtmlProcessorSemanticRulesLIElement.php

@@ -0,0 +1,20 @@
+<?php
+/**
+ * Unit tests covering WP_HTML_Processor compliance with HTML5 semantic parsing rules
+ * for the LI list item element.
+ *
+ * @package WordPress
+ * @subpackage HTML-API
+ *
+ * @since 6.5.0
+ *
+ * @group html-api
+ *
+ * @coversDefaultClass WP_HTML_Processor
+ */
+class Tests_HtmlApi_WpHtmlProcessorSemanticRulesLIElements extends WP_UnitTestCase {
+	/*******************************************************************
+	 * RULES FOR "IN BODY" MODE
+	 *******************************************************************/
+
+}