diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index 3e54b3f085..32c97b63b5 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -324,10 +324,10 @@ public function getDatabasePrefix() {
   private function bootKernel() {
     $this->setSetting('container_yamls', []);
     // Allow for test-specific overrides.
-    $settings_services_file = $this->root . '/sites/default' . '/testing.services.yml';
+    $settings_services_file = $this->root . '/sites/default/testing.services.yml';
     if (file_exists($settings_services_file)) {
       // Copy the testing-specific service overrides in place.
-      $testing_services_file = $this->root . '/' . $this->siteDirectory . '/services.yml';
+      $testing_services_file = $this->siteDirectory . '/services.yml';
       copy($settings_services_file, $testing_services_file);
       $this->setSetting('container_yamls', [$testing_services_file]);
     }
diff --git a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
index f44c9650f6..7ee0ff9ae9 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
@@ -17,6 +17,14 @@
 class KernelTestBaseTest extends KernelTestBase {
 
   /**
+   * {@inheritdoc}
+   */
+  protected function setUpFilesystem() {
+    parent::setUpFilesystem();
+    file_put_contents($this->root . '/sites/default/testing.services.yml', "parameters:\n  testing.services.included: true");
+  }
+
+  /**
    * @covers ::setUpBeforeClass
    */
   public function testSetUpBeforeClass() {
@@ -40,6 +48,7 @@ public function testBootEnvironment() {
                   'sync' => [],
                 ],
               ],
+              'services.yml' => "parameters:\n  testing.services.included: true",
             ],
           ],
         ],
@@ -216,6 +225,13 @@ public function testFileDefaultScheme() {
   }
 
   /**
+   * Tests that testing.service.yml files are loaded.
+   */
+  public function testTestingServicesYml() {
+    $this->assertSame(TRUE, \Drupal::getContainer()->getParameter('testing.services.included'));
+  }
+
+  /**
    * Tests the assumption that local time is in 'Australia/Sydney'.
    */
   public function testLocalTimeZone() {
@@ -300,6 +316,8 @@ protected function tearDown() {
 
       $this->assertTrue(empty($result), 'All test tables have been removed.');
     }
+
+    unlink($this->root . '/sites/default/testing.services.yml');
   }
 
 }