From ee631556b43aca2d55a32d58189da55faa219547 Mon Sep 17 00:00:00 2001
From: Tonya Mork <hellofromtonya@git.wordpress.org>
Date: Mon, 23 Oct 2023 23:37:55 +0000
Subject: [PATCH] Editor: Fix render_duotone_support() to be compatible with
 enhanced pagination.

Some blocks do not have content. For duotone support, blocks without content still need to run through the `render_duotone_support()` to render their duotone CSS.

This fix makes the duotone compatible with the enhanced pagination (introduced in 6.4.0) by making sure that the CSS is always on the page, even when the posts have no featured image. It also prevents the duotone from interfering with other blocks using `wp_unique_id()`.


References:
* [https://github.com/WordPress/gutenberg/pull/55415 Gutenberg PR 55415]

Follow-up to [56226].

Props cbravobernal, luisherranz, hellofromTonya, isabel_brison, jorbin.
Fixes #59694.

git-svn-id: https://develop.svn.wordpress.org/trunk@56991 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-wp-duotone.php          |  2 +-
 .../phpunit/tests/block-supports/duotone.php  | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/class-wp-duotone.php b/src/wp-includes/class-wp-duotone.php
index 1bb8bea5cd..813258c10d 100644
--- a/src/wp-includes/class-wp-duotone.php
+++ b/src/wp-includes/class-wp-duotone.php
@@ -1074,7 +1074,7 @@ class WP_Duotone {
 	 * @return string Filtered block content.
 	 */
 	public static function render_duotone_support( $block_content, $block, $wp_block ) {
-		if ( empty( $block_content ) || ! $block['blockName'] ) {
+		if ( ! $block['blockName'] ) {
 			return $block_content;
 		}
 		$duotone_selector = self::get_selector( $wp_block->block_type );
diff --git a/tests/phpunit/tests/block-supports/duotone.php b/tests/phpunit/tests/block-supports/duotone.php
index 9ec3c70958..eac3d2acac 100644
--- a/tests/phpunit/tests/block-supports/duotone.php
+++ b/tests/phpunit/tests/block-supports/duotone.php
@@ -102,6 +102,33 @@ class Tests_Block_Supports_Duotone extends WP_UnitTestCase {
 		);
 	}
 
+	/**
+	 * Tests whether the CSS declarations are generated even if the block content is
+	 * empty. This is needed to make the CSS output stable across paginations for
+	 * features like the enhanced pagination of the Query block.
+	 *
+	 * @ticket 59694
+	 *
+	 * @covers ::render_duotone_support
+	 */
+	public function test_css_declarations_are_generated_even_with_empty_block_content() {
+		$block                           = array(
+			'blockName' => 'core/image',
+			'attrs'     => array( 'style' => array( 'color' => array( 'duotone' => 'var:preset|duotone|blue-orange' ) ) ),
+		);
+		$wp_block                        = new WP_Block( $block );
+		$block_css_declarations_property = new ReflectionProperty( 'WP_Duotone', 'block_css_declarations' );
+		$block_css_declarations_property->setAccessible( true );
+		$block_css_declarations_property->setValue( $wp_block, array() );
+
+		WP_Duotone::render_duotone_support( '', $block, $wp_block );
+		$actual = $block_css_declarations_property->getValue();
+		// Reset the property's visibility.
+		$block_css_declarations_property->setAccessible( false );
+
+		$this->assertNotEmpty( $actual );
+	}
+
 	/**
 	 * @dataProvider data_is_preset
 	 */