diff --git a/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryCachedTest.php b/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryCachedTest.php
index ef839c9075..e19c557431 100644
--- a/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryCachedTest.php
+++ b/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryCachedTest.php
@@ -17,6 +17,9 @@ class AnnotatedClassDiscoveryCachedTest extends TestCase {
    */
   protected function setUp() {
     parent::setUp();
+    // Ensure FileCacheFactory::DISABLE_CACHE is *not* set, since we're testing
+    // integration with the file cache.
+    FileCacheFactory::setConfiguration([]);
     // Ensure that FileCacheFactory has a prefix.
     FileCacheFactory::setPrefix('prefix');
   }
diff --git a/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php b/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php
index e2de5ca210..2b1ccb2cb0 100644
--- a/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php
+++ b/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php
@@ -13,34 +13,17 @@
  */
 class AnnotatedClassDiscoveryTest extends TestCase {
 
-  /**
-   * Original file cache configuration from before we disable it.
-   *
-   * @var array
-   */
-  protected $originalFileCacheConfig;
-
   /**
    * {@inheritdoc}
    */
   protected function setUp() {
     parent::setUp();
-    // Ensure that the NullFileCache implementation is used for the FileCache as
-    // unit tests should not be relying on caches implicitly.
-    $this->originalFileCacheConfig = FileCacheFactory::getConfiguration();
+    // Ensure the file cache is disabled.
     FileCacheFactory::setConfiguration([FileCacheFactory::DISABLE_CACHE => TRUE]);
     // Ensure that FileCacheFactory has a prefix.
     FileCacheFactory::setPrefix('prefix');
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  protected function tearDown() {
-    FileCacheFactory::setConfiguration($this->originalFileCacheConfig);
-    parent::tearDown();
-  }
-
   /**
    * @covers ::__construct
    * @covers ::getPluginNamespaces
diff --git a/core/tests/Drupal/Tests/UnitTestCase.php b/core/tests/Drupal/Tests/UnitTestCase.php
index 032b8c7e9d..5139f97730 100644
--- a/core/tests/Drupal/Tests/UnitTestCase.php
+++ b/core/tests/Drupal/Tests/UnitTestCase.php
@@ -32,13 +32,6 @@
    */
   protected $root;
 
-  /**
-   * Original file cache configuration from before we disable it.
-   *
-   * @var array
-   */
-  protected $originalFileCacheConfig;
-
   /**
    * {@inheritdoc}
    */
@@ -50,7 +43,6 @@ protected function setUp() {
 
     // Ensure that the NullFileCache implementation is used for the FileCache as
     // unit tests should not be relying on caches implicitly.
-    $this->originalFileCacheConfig = FileCacheFactory::getConfiguration();
     FileCacheFactory::setConfiguration([FileCacheFactory::DISABLE_CACHE => TRUE]);
     // Ensure that FileCacheFactory has a prefix.
     FileCacheFactory::setPrefix('prefix');
@@ -58,14 +50,6 @@ protected function setUp() {
     $this->root = dirname(dirname(substr(__DIR__, 0, -strlen(__NAMESPACE__))));
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  protected function tearDown() {
-    FileCacheFactory::setConfiguration($this->originalFileCacheConfig);
-    parent::tearDown();
-  }
-
   /**
    * Generates a unique random string containing letters and numbers.
    *