diff --git a/system/Boot.php b/system/Boot.php
index 00ae0f61de25..6902684ca612 100644
--- a/system/Boot.php
+++ b/system/Boot.php
@@ -20,6 +20,9 @@
 use Config\Paths;
 use Config\Services;
 
+/**
+ * Bootstrap for the application
+ */
 class Boot
 {
     /**
@@ -35,7 +38,9 @@ public static function bootWeb(Paths $paths): void
         static::defineEnvironment();
         static::loadEnvironmentBootstrap($paths);
         static::definePathConstant($paths);
-        static::loadConstants();
+        if (! defined('APP_NAMESPACE')) {
+            static::loadConstants();
+        }
         static::loadCommonFunctions();
         static::loadAutoloader();
         static::setExceptionHandler();
@@ -52,6 +57,23 @@ public static function bootSpark(Paths $paths): void
         static::defineEnvironment();
         static::loadEnvironmentBootstrap($paths);
         static::definePathConstant($paths);
+        if (! defined('APP_NAMESPACE')) {
+            static::loadConstants();
+        }
+        static::loadCommonFunctions();
+        static::loadAutoloader();
+        static::setExceptionHandler();
+        static::checkMissingExtensions();
+        static::initializeKint();
+    }
+
+    /**
+     * @used-by system/Test/bootstrap.php
+     */
+    public static function bootTest(Paths $paths): void
+    {
+        static::loadDotEnv($paths);
+        static::loadEnvironmentBootstrap($paths, false);
         static::loadConstants();
         static::loadCommonFunctions();
         static::loadAutoloader();
@@ -72,21 +94,27 @@ protected static function loadDotEnv(Paths $paths): void
     protected static function defineEnvironment(): void
     {
         if (! defined('ENVIRONMENT')) {
+            // @phpstan-ignore-next-line
             $env = $_ENV['CI_ENVIRONMENT'] ?? $_SERVER['CI_ENVIRONMENT'] ?? getenv('CI_ENVIRONMENT');
+
             define('ENVIRONMENT', ($env !== false) ? $env : 'production');
             unset($env);
         }
     }
 
-    protected static function loadEnvironmentBootstrap(Paths $paths): void
+    protected static function loadEnvironmentBootstrap(Paths $paths, bool $exit = true): void
     {
         if (is_file($paths->appDirectory . '/Config/Boot/' . ENVIRONMENT . '.php')) {
             require_once $paths->appDirectory . '/Config/Boot/' . ENVIRONMENT . '.php';
-        } else {
+
+            return;
+        }
+
+        if ($exit) {
             header('HTTP/1.1 503 Service Unavailable.', true, 503);
             echo 'The application environment is not set correctly.';
 
-            exit(EXIT_ERROR); // EXIT_ERROR
+            exit(EXIT_ERROR);
         }
     }
 
@@ -125,9 +153,7 @@ protected static function definePathConstant(Paths $paths): void
 
     protected static function loadConstants(): void
     {
-        if (! defined('APP_NAMESPACE')) {
-            require_once APPPATH . 'Config/Constants.php';
-        }
+        require_once APPPATH . 'Config/Constants.php';
     }
 
     protected static function loadCommonFunctions(): void
diff --git a/system/Test/bootstrap.php b/system/Test/bootstrap.php
index 08c6b2e52519..cb70a435831b 100644
--- a/system/Test/bootstrap.php
+++ b/system/Test/bootstrap.php
@@ -11,9 +11,7 @@
  * the LICENSE file that was distributed with this source code.
  */
 
-use CodeIgniter\Config\DotEnv;
-use Config\Autoload;
-use Config\Modules;
+use CodeIgniter\Boot;
 use Config\Paths;
 use Config\Services;
 
@@ -80,85 +78,9 @@
  * and fires up an environment-specific bootstrapping.
  */
 
-// LOAD DOTENV FILE
-// Load environment settings from .env files into $_SERVER and $_ENV
-require_once $paths->systemDirectory . '/Config/DotEnv.php';
-(new DotEnv($paths->appDirectory . '/../'))->load();
-
-/*
- * ---------------------------------------------------------------
- * LOAD ENVIRONMENT BOOTSTRAP
- * ---------------------------------------------------------------
- *
- * Load any custom boot files based upon the current environment.
- * If no boot file exists, we shouldn't continue because something
- * is wrong. At the very least, they should have error reporting setup.
- */
-
-if (is_file(APPPATH . 'Config/Boot/' . ENVIRONMENT . '.php')) {
-    require_once APPPATH . 'Config/Boot/' . ENVIRONMENT . '.php';
-}
-
-/*
- * ---------------------------------------------------------------
- * GRAB OUR CONSTANTS
- * ---------------------------------------------------------------
- */
-
-require_once APPPATH . 'Config/Constants.php';
-
-/*
- * ---------------------------------------------------------------
- * LOAD COMMON FUNCTIONS
- * ---------------------------------------------------------------
- */
-
-// Load Common.php from App then System
-if (is_file(APPPATH . 'Common.php')) {
-    require_once APPPATH . 'Common.php';
-}
-
-require_once SYSTEMPATH . 'Common.php';
-
-/*
- * ---------------------------------------------------------------
- * LOAD OUR AUTOLOADER
- * ---------------------------------------------------------------
- *
- * The autoloader allows all of the pieces to work together in the
- * framework. We have to load it here, though, so that the config
- * files can use the path constants.
- */
-
-require_once SYSTEMPATH . 'Config/AutoloadConfig.php';
-require_once APPPATH . 'Config/Autoload.php';
-require_once SYSTEMPATH . 'Modules/Modules.php';
-require_once APPPATH . 'Config/Modules.php';
-
-require_once SYSTEMPATH . 'Autoloader/Autoloader.php';
-require_once SYSTEMPATH . 'Config/BaseService.php';
-require_once SYSTEMPATH . 'Config/Services.php';
-require_once APPPATH . 'Config/Services.php';
-
-// Initialize and register the loader with the SPL autoloader stack.
-Services::autoloader()->initialize(new Autoload(), new Modules())->register();
-Services::autoloader()->loadHelpers();
-
-/*
- * ---------------------------------------------------------------
- * SET EXCEPTION AND ERROR HANDLERS
- * ---------------------------------------------------------------
- */
-
-Services::exceptions()->initialize();
-
-/*
- * ---------------------------------------------------------------
- * INITIALIZE KINT
- * ---------------------------------------------------------------
- */
-
-Services::autoloader()->initializeKint(CI_DEBUG);
+// LOAD THE FRAMEWORK BOOTSTRAP FILE
+require rtrim($paths->systemDirectory, '\\/ ') . DIRECTORY_SEPARATOR . 'Boot.php';
+Boot::bootTest($paths);
 
 /*
  * ---------------------------------------------------------------