From c1b8f1f72ac1b27edf7659cceeb552921b1e55bd Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Fri, 21 Aug 2015 01:10:34 +0000
Subject: [PATCH] In `Walker_CategoryDropdown::start_el()`, cast values to
 strings before deciding whether to append 'selected' attribute.

As of [32484], `wp_dropdown_categories()` uses the `$value_field` value to
decide whether a given `<option>` should be 'selected'. However, `$value_field`
can refer to a value that is a string, such as a category's slug. This causes
problems when doing a loose comparison (`==`) with the value of the `'selected'`
parameter, which defaults to `0`, because when doing a loose comparison
between an integer and a string, PHP will cast the string to an integer. This
creates false matches, resulting in `<option>` elements getting a 'selected'
attribute incorrectly.

We address the issue by casting the comparison values to strings, and then
using the strict comparison operator `===`.

Fixes #33452 for trunk.

git-svn-id: https://develop.svn.wordpress.org/trunk@33681 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/category-template.php |  3 +-
 tests/phpunit/tests/category.php      | 43 +++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/category-template.php b/src/wp-includes/category-template.php
index d29ae479ec..6bac6c11b7 100644
--- a/src/wp-includes/category-template.php
+++ b/src/wp-includes/category-template.php
@@ -1207,7 +1207,8 @@ class Walker_CategoryDropdown extends Walker {
 
 		$output .= "\t<option class=\"level-$depth\" value=\"" . esc_attr( $category->{$value_field} ) . "\"";
 
-		if ( $category->{$value_field} == $args['selected'] )
+		// Type-juggling causes false matches, so we force everything to a string.
+		if ( (string) $category->{$value_field} === (string) $args['selected'] )
 			$output .= ' selected="selected"';
 		$output .= '>';
 		$output .= $pad.$cat_name;
diff --git a/tests/phpunit/tests/category.php b/tests/phpunit/tests/category.php
index b23be34edd..470f0e4f9f 100644
--- a/tests/phpunit/tests/category.php
+++ b/tests/phpunit/tests/category.php
@@ -351,4 +351,47 @@ class Tests_Category extends WP_UnitTestCase {
 
 		$this->assertContains( "value=\"test_category_2\" selected=\"selected\"", $found );
 	}
+
+	/**
+	 * @ticket 33452
+	 */
+	public function test_wp_dropdown_categories_show_option_all_should_be_selected_if_no_selected_value_is_explicitly_passed_and_value_field_does_not_have_string_values() {
+		$cats = $this->factory->category->create_many( 3 );
+
+		$found = wp_dropdown_categories( array(
+			'echo' => 0,
+			'hide_empty' => 0,
+			'show_option_all' => 'Foo',
+			'value_field' => 'slug',
+		) );
+
+		$this->assertContains( "value='0' selected='selected'", $found );
+
+		foreach ( $cats as $cat ) {
+			$_cat = get_term( $cat, 'category' );
+			$this->assertNotContains( 'value="' . $_cat->slug . '" selected="selected"', $found );
+		}
+	}
+
+	/**
+	 * @ticket 33452
+	 */
+	public function test_wp_dropdown_categories_show_option_all_should_be_selected_if_selected_value_of_0_string_is_explicitly_passed_and_value_field_does_not_have_string_values() {
+		$cats = $this->factory->category->create_many( 3 );
+
+		$found = wp_dropdown_categories( array(
+			'echo' => 0,
+			'hide_empty' => 0,
+			'show_option_all' => 'Foo',
+			'value_field' => 'slug',
+			'selected' => '0',
+		) );
+
+		$this->assertContains( "value='0' selected='selected'", $found );
+
+		foreach ( $cats as $cat ) {
+			$_cat = get_term( $cat, 'category' );
+			$this->assertNotContains( 'value="' . $_cat->slug . '" selected="selected"', $found );
+		}
+	}
 }