Global Styles: Fix for third-party blocks

src/wp-includes/global-styles-and-settings.php

@@ -218,14 +218,18 @@ function wp_add_global_styles_for_blocks() {
 			continue;
 		}
 
+		$stylesheet_handle = 'global-styles';
 		if ( isset( $metadata['name'] ) ) {
-			$block_name = str_replace( 'core/', '', $metadata['name'] );
 			/*
 			 * These block styles are added on block_render.
 			 * This hooks inline CSS to them so that they are loaded conditionally
 			 * based on whether or not the block is used on the page.
 			 */
-			wp_add_inline_style( 'wp-block-' . $block_name, $block_css );
+			if ( str_starts_with( $metadata['name'], 'core/' ) ) {
+				$block_name        = str_replace( 'core/', '', $metadata['name'] );
+				$stylesheet_handle = 'wp-block-' . $block_name;
+			}
+			wp_add_inline_style( $stylesheet_handle, $block_css );
 		}
 
 		// The likes of block element styles from theme.json do not have  $metadata['name'] set.
@@ -242,8 +246,11 @@ function ( $item ) {
 				)
 			);
 			if ( isset( $result[0] ) ) {
-				$block_name = str_replace( 'core/', '', $result[0] );
-				wp_add_inline_style( 'wp-block-' . $block_name, $block_css );
+				if ( str_starts_with( $result[0], 'core/' ) ) {
+					$block_name        = str_replace( 'core/', '', $result[0] );
+					$stylesheet_handle = 'wp-block-' . $block_name;
+				}
+				wp_add_inline_style( $stylesheet_handle, $block_css );
 			}
 		}
 	}

tests/phpunit/data/themedir1/block-theme/theme.json

@@ -69,6 +69,11 @@
 				"filter": {
 					"duotone": "var(--wp--preset--duotone--custom-duotone)"
 				}
+			},
+			"my/third-party-block": {
+				"color": {
+					"background": "hotpink"
+				}
 			}
 		},
 		"elements": {

tests/phpunit/tests/theme/wpGetGlobalStylesForBlocks.php

@@ -0,0 +1,94 @@
+<?php
+
+/**
+ * Tests wp_add_global_styles_for_blocks().
+ *
+ * @group themes
+ */
+class Tests_Theme_wpGetGlobalStylesForBlocks extends WP_UnitTestCase {
+
+	/**
+	 * Theme root directory.
+	 *
+	 * @var string
+	 */
+	private $theme_root;
+
+	/**
+	 * Original theme directory.
+	 *
+	 * @var string
+	 */
+	private $orig_theme_dir;
+
+	public function set_up() {
+		parent::set_up();
+
+		$this->orig_theme_dir = $GLOBALS['wp_theme_directories'];
+		$this->theme_root     = realpath( DIR_TESTDATA . '/themedir1' );
+
+		// /themes is necessary as theme.php functions assume /themes is the root if there is only one root.
+		$GLOBALS['wp_theme_directories'] = array( WP_CONTENT_DIR . '/themes', $this->theme_root );
+
+		// Set up the new root.
+		add_filter( 'theme_root', array( $this, 'filter_set_theme_root' ) );
+		add_filter( 'stylesheet_root', array( $this, 'filter_set_theme_root' ) );
+		add_filter( 'template_root', array( $this, 'filter_set_theme_root' ) );
+
+		// Clear caches.
+		wp_clean_themes_cache();
+		unset( $GLOBALS['wp_themes'] );
+	}
+
+	public function tear_down() {
+		$GLOBALS['wp_theme_directories'] = $this->orig_theme_dir;
+
+		// Clear up the filters to modify the theme root.
+		remove_filter( 'theme_root', array( $this, 'filter_set_theme_root' ) );
+		remove_filter( 'stylesheet_root', array( $this, 'filter_set_theme_root' ) );
+		remove_filter( 'template_root', array( $this, 'filter_set_theme_root' ) );
+
+		wp_clean_themes_cache();
+		unset( $GLOBALS['wp_themes'] );
+
+		parent::tear_down();
+	}
+
+	/**
+	 * Cleans up global scope.
+	 *
+	 * @global WP_Styles $wp_styles
+	 */
+	public function clean_up_global_scope() {
+		global $wp_styles;
+		parent::clean_up_global_scope();
+		$wp_styles = null;
+	}
+
+	public function filter_set_theme_root() {
+		return $this->theme_root;
+	}
+
+	public function test_styles_for_blocks() {
+		switch_theme( 'block-theme' );
+
+		// The 3rd party block styles are only missing
+		// if the assets are loaded per block.
+		add_filter( 'should_load_separate_core_block_assets', '__return_true' );
+
+		$name     = 'my/third-party-block';
+		$settings = array(
+			'icon'            => 'text',
+			'category'        => 'common',
+			'render_callback' => 'foo',
+		);
+		register_block_type( $name, $settings );
+		wp_enqueue_global_styles();
+		unregister_block_type( $name );
+
+		$this->assertStringContainsString( '.wp-block-my-third-party-block{background-color: hotpink;}', get_echo( 'wp_print_styles' ), '3rd party block styles are included' );
+
+		switch_theme( WP_DEFAULT_THEME );
+	}
+
+}