Ensure Composer is properly loaded during unit tests when installing (#…

…542)

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## v0.12.13 - 2024-05-07
+
+### Fixed
+
+- Ensure that Composer is properly loaded during unit tests when installing
+  WordPress.
+
 ## v0.12.12 - 2024-01-08
 
 ### Added

src/mantle/testing/class-utils.php

@@ -459,7 +459,7 @@ public static function command( $command, &$exit_code = null ) {
 	 * Ensure that Composer is loaded for the current environment.
 	 */
 	public static function ensure_composer_loaded() {
-		if ( class_exists( 'Composer\Autoload\ClassLoader' ) ) {
+		if ( class_exists( \Composer\Autoload\ClassLoader::class ) && class_exists( Str::class ) ) {
 			return;
 		}