From a4caf720e981c25ad5b35aae1dbcb66eca565b88 Mon Sep 17 00:00:00 2001
From: ramon <ramonjd@gmail.com>
Date: Wed, 14 Aug 2024 14:21:09 +1000
Subject: [PATCH] Ensures that background image theme.json objects are
 replaced, and not merged. The image object represents a single unit. We want
 to prevent "cross contamination"

---
 src/wp-includes/class-wp-theme-json.php   |  20 ++++
 tests/phpunit/tests/theme/wpThemeJson.php | 109 ++++++++++++++++++++++
 2 files changed, 129 insertions(+)

diff --git a/src/wp-includes/class-wp-theme-json.php b/src/wp-includes/class-wp-theme-json.php
index eb784f0d1fce1..9bef842db836e 100644
--- a/src/wp-includes/class-wp-theme-json.php
+++ b/src/wp-includes/class-wp-theme-json.php
@@ -3110,6 +3110,7 @@ protected static function get_metadata_boolean( $data, $path, $default_value = f
 	 *
 	 * @since 5.8.0
 	 * @since 5.9.0 Duotone preset also has origins.
+	 * @since 6.7.0 Replace background image objects during merge.
 	 *
 	 * @param WP_Theme_JSON $incoming Data to merge.
 	 */
@@ -3233,6 +3234,25 @@ public function merge( $incoming ) {
 				}
 			}
 		}
+
+		/*
+		 * Style values are merged at the leaf level, however
+		 * some values provide exceptions, namely style values that are
+		 * objects and represent unique definitions for the style.
+		 */
+		$style_nodes = static::get_styles_block_nodes();
+		foreach ( $style_nodes as $style_node ) {
+			$path = $style_node['path'];
+			/*
+			 * Background image styles should be replaced, not merged,
+			 * as they themselves are specific object definitions for the style.
+			 */
+			$background_image_path = array_merge( $path, static::PROPERTIES_METADATA['background-image'] );
+			$content               = _wp_array_get( $incoming_data, $background_image_path, null );
+			if ( isset( $content ) ) {
+				_wp_array_set( $this->theme_json, $background_image_path, $content );
+			}
+		}
 	}
 
 	/**
diff --git a/tests/phpunit/tests/theme/wpThemeJson.php b/tests/phpunit/tests/theme/wpThemeJson.php
index 15d101f485c2a..dbb82482fe440 100644
--- a/tests/phpunit/tests/theme/wpThemeJson.php
+++ b/tests/phpunit/tests/theme/wpThemeJson.php
@@ -2334,6 +2334,115 @@ public function test_merge_incoming_data_presets_use_default_names() {
 		$this->assertSameSetsWithIndex( $expected, $actual );
 	}
 
+	/**
+	 * @ticket 61858
+	 */
+	public function test_merge_incoming_background_styles() {
+		$theme_json = new WP_Theme_JSON(
+			array(
+				'version' => WP_Theme_JSON::LATEST_SCHEMA,
+				'styles'  => array(
+					'background' => array(
+						'backgroundImage' => array(
+							'url' => 'http://example.org/quote.png',
+						),
+						'backgroundSize'  => 'cover',
+					),
+					'blocks'     => array(
+						'core/group' => array(
+							'background' => array(
+								'backgroundImage'      => array(
+									'ref' => 'styles.blocks.core/verse.background.backgroundImage',
+								),
+								'backgroundAttachment' => 'fixed',
+							),
+						),
+						'core/quote' => array(
+							'background' => array(
+								'backgroundImage'      => array(
+									'url' => 'http://example.org/quote.png',
+								),
+								'backgroundAttachment' => array(
+									'ref' => 'styles.blocks.core/group.background.backgroundAttachment',
+								),
+							),
+						),
+					),
+				),
+			)
+		);
+
+		$update_background_image_styles = array(
+			'version' => WP_Theme_JSON::LATEST_SCHEMA,
+			'styles'  => array(
+				'background' => array(
+					'backgroundSize' => 'contain',
+				),
+				'blocks'     => array(
+					'core/group' => array(
+						'background' => array(
+							'backgroundImage' => array(
+								'url' => 'http://example.org/group.png',
+							),
+						),
+					),
+					'core/quote' => array(
+						'background' => array(
+							'backgroundAttachment' => 'fixed',
+						),
+					),
+					'core/verse' => array(
+						'background' => array(
+							'backgroundImage' => array(
+								'ref' => 'styles.blocks.core/group.background.backgroundImage',
+							),
+						),
+					),
+				),
+			),
+		);
+		$expected                       = array(
+			'version' => WP_Theme_JSON::LATEST_SCHEMA,
+			'styles'  => array(
+				'background' => array(
+					'backgroundImage' => array(
+						'url' => 'http://example.org/quote.png',
+					),
+					'backgroundSize'  => 'contain',
+				),
+				'blocks'     => array(
+					'core/group' => array(
+						'background' => array(
+							'backgroundImage'      => array(
+								'url' => 'http://example.org/group.png',
+							),
+							'backgroundAttachment' => 'fixed',
+						),
+					),
+					'core/quote' => array(
+						'background' => array(
+							'backgroundImage'      => array(
+								'url' => 'http://example.org/quote.png',
+							),
+							'backgroundAttachment' => 'fixed',
+						),
+					),
+					'core/verse' => array(
+						'background' => array(
+							'backgroundImage' => array(
+								'ref' => 'styles.blocks.core/group.background.backgroundImage',
+							),
+						),
+					),
+				),
+			),
+		);
+		$theme_json->merge( new WP_Theme_JSON( $update_background_image_styles ) );
+		$actual = $theme_json->get_raw_data();
+
+		$this->assertEqualSetsWithIndex( $expected, $actual );
+	}
+
 	/**
 	 * @ticket 54336
 	 */