diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/ClassloaderTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/ClassloaderTest.php
new file mode 100644
index 0000000..75476c0
--- /dev/null
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/ClassloaderTest.php
@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\simpletest\Tests\ClassloaderTest.
+ */
+
+namespace Drupal\simpletest\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests the classloader during SimpleTest runs.
+ */
+class ClassloaderTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('simpletest');
+
+  public static function getInfo() {
+    return array(
+      'name' => 'SimpleTest class loading',
+      'description' => 'Tests the classloader during SimpleTest runs.',
+      'group' => 'SimpleTest'
+    );
+  }
+
+  /**
+   * Namespaces for disabled modules are only added if they contain tests.
+   */
+  protected function testDisabledModuleClassLoading() {
+    $namespaces = drupal_classloader()->getNamespaces();
+    $this->assertTrue(isset($namespaces['Drupal\\config']), 'Disabled modules that provide test classes are loaded.');
+    $this->assertTrue(!isset($namespaces['Drupal\\config_test']), 'Disabled modules that do not provide test classes are not loaded.');
+  }
+
+}