diff --git a/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php b/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php
index 85c6f010f3..e2de5ca210 100644
--- a/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php
+++ b/core/tests/Drupal/Tests/Component/Annotation/AnnotatedClassDiscoveryTest.php
@@ -14,18 +14,34 @@
 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();
     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 5139f97730..032b8c7e9d 100644
--- a/core/tests/Drupal/Tests/UnitTestCase.php
+++ b/core/tests/Drupal/Tests/UnitTestCase.php
@@ -33,6 +33,13 @@
   protected $root;
 
   /**
+   * Original file cache configuration from before we disable it.
+   *
+   * @var array
+   */
+  protected $originalFileCacheConfig;
+
+  /**
    * {@inheritdoc}
    */
   protected function setUp() {
@@ -43,6 +50,7 @@ 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');
@@ -51,6 +59,14 @@ protected function setUp() {
   }
 
   /**
+   * {@inheritdoc}
+   */
+  protected function tearDown() {
+    FileCacheFactory::setConfiguration($this->originalFileCacheConfig);
+    parent::tearDown();
+  }
+
+  /**
    * Generates a unique random string containing letters and numbers.
    *
    * @param int $length