Code review for 6.1.1 global stylesheet invalidation testing plugin

wp-test-56970.php

@@ -1,7 +1,50 @@
 <?php
 /**
  * Plugin Name: Test for Trac 56970
- * Description: Clears global stylesheet transient. See <a href="https://core.trac.wordpress.org/ticket/56970">Trac 56970</a>.
+ * Description: Clears the global stylesheet transient after upgrade to 6.1.1. See <a href="https://core.trac.wordpress.org/ticket/56970">Trac 56970</a>.
  * Version: 0.1
  */
 
+// Initialize plugin.
+WP_Test_56970_Controller::init();
+
+class WP_Test_56970_Controller {
+	public static function init() {
+		add_action( 'init', 'wp_test_56970_init' );
+		register_activation_hook( __FILE__, array( __CLASS__, 'activate' ) );
+		register_deactivation_hook( __FILE__, array( __CLASS__, 'deactivate' ) );
+	}
+	public static function activate() {
+		add_option( 'wp_test_56970_run', true );
+		register_uninstall_hook( __FILE__, array( __CLASS__, 'uninstall' ) );
+	}
+	public static function deactivate() {
+		delete_option( 'wp_test_56970_run' );
+	}
+	public static function uninstall() {
+		self::deactivate();
+	}
+}
+
+function wp_test_56970_init() {
+	global $wp_version;
+
+	if ( ! get_option( 'wp_test_56970_run' ) ) {
+		return;
+	}
+
+	// Issue described in Trac 56970 only affects upgrade from 5.9/6.0 to 6.1.1.
+	if ( '6.1.1' === $wp_version ) {
+		// Name of `global_styles_` stylesheet transient, e.g. 'global_styles_twentytwentyone'.
+		$transient_name = 'global_styles_' . get_stylesheet();
+		// Hook to invalidate the transient.
+		add_filter( "transient_$transient_name", 'wp_test_56970_transient_global_styles_stylesheet', 10, 2 );
+	}
+}
+
+function wp_test_56970_transient_global_styles_stylesheet( $value, $transient ) {
+	// Prevent hook from firing again.
+	update_option( 'wp_test_56970_run', false );
+
+	return false;
+}