From b66fcb55e5d42b6e4d18a100dc3762e3d9b5ed6d Mon Sep 17 00:00:00 2001
From: Jb Audras <audrasjb@git.wordpress.org>
Date: Tue, 27 Jun 2023 15:25:00 +0000
Subject: [PATCH] Menus: Allow themes and plugins to pass HTML attributes to
 various Nav Walker outputs.

This introduces a new set of hooks that can be used to filter various HTML elements of the Nav Walker, in order to output the desired HTML attributes:

- List items: `nav_menu_item_attributes`
- Submenu `<ul>` element: `nav_menu_submenu_attributes`

Props davidwebca, danyk4, costdev, peterwilsoncc, audrasjb, oglekler.
Fixes #57140.




git-svn-id: https://develop.svn.wordpress.org/trunk@56067 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-walker-nav-menu.php    |  78 ++++++++++---
 tests/phpunit/tests/menu/walker-nav-menu.php | 113 +++++++++++++++++++
 2 files changed, 177 insertions(+), 14 deletions(-)

diff --git a/src/wp-includes/class-walker-nav-menu.php b/src/wp-includes/class-walker-nav-menu.php
index e683a3d5c8..4683970c61 100644
--- a/src/wp-includes/class-walker-nav-menu.php
+++ b/src/wp-includes/class-walker-nav-menu.php
@@ -73,9 +73,27 @@ class Walker_Nav_Menu extends Walker {
 		 * @param int      $depth   Depth of menu item. Used for padding.
 		 */
 		$class_names = implode( ' ', apply_filters( 'nav_menu_submenu_css_class', $classes, $args, $depth ) );
-		$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
 
-		$output .= "{$n}{$indent}<ul$class_names>{$n}";
+		$atts          = array();
+		$atts['class'] = ! empty( $class_names ) ? $class_names : '';
+
+		/**
+		 * Filters the HTML attributes applied to a menu list element.
+		 *
+		 * @since 6.3.0
+		 *
+		 * @param array $atts {
+		 *     The HTML attributes applied to the `<ul>` element, empty strings are ignored.
+		 *
+		 *     @type string $class    HTML CSS class attribute.
+		 * }
+		 * @param stdClass $args      An object of `wp_nav_menu()` arguments.
+		 * @param int      $depth     Depth of menu item. Used for padding.
+		 */
+		$atts       = apply_filters( 'nav_menu_submenu_attributes', $atts, $args, $depth );
+		$attributes = $this->build_atts( $atts );
+
+		$output .= "{$n}{$indent}<ul{$attributes}>{$n}";
 	}
 
 	/**
@@ -156,7 +174,6 @@ class Walker_Nav_Menu extends Walker {
 		 * @param int      $depth     Depth of menu item. Used for padding.
 		 */
 		$class_names = implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $menu_item, $args, $depth ) );
-		$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
 
 		/**
 		 * Filters the ID attribute applied to a menu item's list item element.
@@ -170,9 +187,30 @@ class Walker_Nav_Menu extends Walker {
 		 * @param int      $depth        Depth of menu item. Used for padding.
 		 */
 		$id = apply_filters( 'nav_menu_item_id', 'menu-item-' . $menu_item->ID, $menu_item, $args, $depth );
-		$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';
 
-		$output .= $indent . '<li' . $id . $class_names . '>';
+		$li_atts          = array();
+		$li_atts['id']    = ! empty( $id ) ? $id : '';
+		$li_atts['class'] = ! empty( $class_names ) ? $class_names : '';
+
+		/**
+		 * Filters the HTML attributes applied to a menu's list item element.
+		 *
+		 * @since 6.3.0
+		 *
+		 * @param array $li_atts {
+		 *     The HTML attributes applied to the menu item's `<li>` element, empty strings are ignored.
+		 *
+		 *     @type string $class        HTML CSS class attribute.
+		 *     @type string $id           HTML id attribute.
+		 * }
+		 * @param WP_Post  $menu_item The current menu item object.
+		 * @param stdClass $args      An object of wp_nav_menu() arguments.
+		 * @param int      $depth     Depth of menu item. Used for padding.
+		 */
+		$li_atts       = apply_filters( 'nav_menu_item_attributes', $li_atts, $menu_item, $args, $depth );
+		$li_attributes = $this->build_atts( $li_atts );
+
+		$output .= $indent . '<li' . $li_attributes . '>';
 
 		$atts           = array();
 		$atts['title']  = ! empty( $menu_item->attr_title ) ? $menu_item->attr_title : '';
@@ -214,15 +252,8 @@ class Walker_Nav_Menu extends Walker {
 		 * @param stdClass $args      An object of wp_nav_menu() arguments.
 		 * @param int      $depth     Depth of menu item. Used for padding.
 		 */
-		$atts = apply_filters( 'nav_menu_link_attributes', $atts, $menu_item, $args, $depth );
-
-		$attributes = '';
-		foreach ( $atts as $attr => $value ) {
-			if ( is_scalar( $value ) && '' !== $value && false !== $value ) {
-				$value       = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
-				$attributes .= ' ' . $attr . '="' . $value . '"';
-			}
-		}
+		$atts       = apply_filters( 'nav_menu_link_attributes', $atts, $menu_item, $args, $depth );
+		$attributes = $this->build_atts( $atts );
 
 		/** This filter is documented in wp-includes/post-template.php */
 		$title = apply_filters( 'the_title', $menu_item->title, $menu_item->ID );
@@ -286,4 +317,23 @@ class Walker_Nav_Menu extends Walker {
 		$output .= "</li>{$n}";
 	}
 
+	/**
+	 * Builds a string of HTML attributes from an array of key/value pairs.
+	 * Empty values are ignored.
+	 *
+	 * @since 6.3.0
+	 *
+	 * @param  array $atts Optional. An array of HTML attribute key/value pairs. Default empty array.
+	 * @return string A string of HTML attributes.
+	 */
+	protected function build_atts( $atts = array() ) {
+		$attribute_string = '';
+		foreach ( $atts as $attr => $value ) {
+			if ( false !== $value && '' !== $value && is_scalar( $value ) ) {
+				$value             = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
+				$attribute_string .= ' ' . $attr . '="' . $value . '"';
+			}
+		}
+		return $attribute_string;
+	}
 }
diff --git a/tests/phpunit/tests/menu/walker-nav-menu.php b/tests/phpunit/tests/menu/walker-nav-menu.php
index 0c38502f9e..1fa255ef61 100644
--- a/tests/phpunit/tests/menu/walker-nav-menu.php
+++ b/tests/phpunit/tests/menu/walker-nav-menu.php
@@ -365,4 +365,117 @@ class Tests_Menu_Walker_Nav_Menu extends WP_UnitTestCase {
 
 		$this->assertStringContainsString( 'rel="privacy-policy"', $output );
 	}
+
+	/**
+	 * Tests that `Walker_Nav_Menu::start_lvl()` applies 'nav_menu_submenu_attributes' filters.
+	 *
+	 * @ticket 57278
+	 *
+	 * @covers Walker_Nav_Menu::start_lvl
+	 */
+	public function test_start_lvl_should_apply_nav_menu_submenu_attributes_filters() {
+		$output = '';
+		$args   = (object) array(
+			'before'      => '',
+			'after'       => '',
+			'link_before' => '',
+			'link_after'  => '',
+		);
+
+		$filter = new MockAction();
+		add_filter( 'nav_menu_submenu_attributes', array( $filter, 'filter' ) );
+
+		$this->walker->start_lvl( $output, 0, $args );
+
+		$this->assertSame( 1, $filter->get_call_count() );
+	}
+
+	/**
+	 * Tests that `Walker_Nav_Menu::start_el()` applies 'nav_menu_item_attributes' filters.
+	 *
+	 * @ticket 57278
+	 *
+	 * @covers Walker_Nav_Menu::start_el
+	 */
+	public function test_start_el_should_apply_nav_menu_item_attributes_filters() {
+		$output  = '';
+		$post_id = self::factory()->post->create();
+		$item    = (object) array(
+			'ID'        => $post_id,
+			'object_id' => $post_id,
+			'title'     => get_the_title( $post_id ),
+			'target'    => '',
+			'xfn'       => '',
+			'current'   => false,
+		);
+		$args    = (object) array(
+			'before'      => '',
+			'after'       => '',
+			'link_before' => '',
+			'link_after'  => '',
+		);
+
+		$filter = new MockAction();
+		add_filter( 'nav_menu_item_attributes', array( $filter, 'filter' ) );
+
+		$this->walker->start_el( $output, $item, 0, $args );
+
+		$this->assertSame( 1, $filter->get_call_count() );
+	}
+
+	/**
+	 * Tests that `Walker_Nav_Menu::build_atts()` builds attributes correctly.
+	 *
+	 * @ticket 57278
+	 *
+	 * @covers Walker_Nav_Menu::build_atts
+	 *
+	 * @dataProvider data_build_atts_should_build_attributes
+	 *
+	 * @param array  $atts     An array of HTML attribute key/value pairs.
+	 * @param string $expected The expected built attributes.
+	 */
+	public function test_build_atts_should_build_attributes( $atts, $expected ) {
+		$build_atts_reflection = new ReflectionMethod( $this->walker, 'build_atts' );
+
+		$build_atts_reflection->setAccessible( true );
+		$actual = $build_atts_reflection->invoke( $this->walker, $atts );
+		$build_atts_reflection->setAccessible( false );
+
+		$this->assertSame( $expected, $actual );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_build_atts_should_build_attributes() {
+		return array(
+			'an empty attributes array'                   => array(
+				'atts'     => array(),
+				'expected' => '',
+			),
+			'attributes containing a (bool) false value'  => array(
+				'atts'     => array( 'disabled' => false ),
+				'expected' => '',
+			),
+			'attributes containing an empty string value' => array(
+				'atts'     => array( 'id' => '' ),
+				'expected' => '',
+			),
+			'attributes containing a non-scalar value'    => array(
+				'atts'     => array( 'data-items' => new stdClass() ),
+				'expected' => '',
+			),
+			'attributes containing a "href" -> should escape the URL' => array(
+				'atts'     => array( 'href' => 'https://example.org/A File With Spaces.pdf' ),
+				'expected' => ' href="https://example.org/A%20File%20With%20Spaces.pdf"',
+			),
+			'attributes containing a non-"href" attribute -> should escape the value' => array(
+				'atts'     => array( 'id' => 'hello&goodbye' ),
+				'expected' => ' id="hello&amp;goodbye"',
+			),
+		);
+	}
 }