diff --git a/core/modules/simpletest/simpletest.services.yml b/core/modules/simpletest/simpletest.services.yml
index 0335afa5b1..c7c145e763 100644
--- a/core/modules/simpletest/simpletest.services.yml
+++ b/core/modules/simpletest/simpletest.services.yml
@@ -1,15 +1,9 @@
 services:
   test_discovery:
     class: Drupal\simpletest\TestDiscovery
-    arguments: ['@app.root', '@class_loader', '@module_handler', '@?cache.simpletest']
-  cache.simpletest:
-    class: Drupal\Core\Cache\CacheBackendInterface
-    tags:
-      - { name: cache.bin }
-    factory: cache_factory:get
-    arguments: [simpletest]
+    arguments: ['@app.root', '@class_loader', '@module_handler', '@?cache.discovery']
   cache_context.test_discovery:
     class: Drupal\simpletest\Cache\Context\TestDiscoveryCacheContext
-    arguments: ['@test_discovery', '@private_key', '@cache.simpletest']
+    arguments: ['@test_discovery', '@private_key', '@cache.discovery']
     tags:
       - { name: cache.context}
diff --git a/core/modules/simpletest/src/Cache/Context/TestDiscoveryCacheContext.php b/core/modules/simpletest/src/Cache/Context/TestDiscoveryCacheContext.php
index d9f12be003..13bfc655f1 100644
--- a/core/modules/simpletest/src/Cache/Context/TestDiscoveryCacheContext.php
+++ b/core/modules/simpletest/src/Cache/Context/TestDiscoveryCacheContext.php
@@ -31,11 +31,11 @@ class TestDiscoveryCacheContext implements CacheContextInterface {
   protected $privateKey;
 
   /**
-   * The cache backend for simpletest.
+   * The cache backend for TestDiscovery.
    *
    * @var \Drupal\Core\Cache\CacheBackendInterface
    */
-  protected $simpletestCache;
+  protected $discoveryCache;
 
   /**
    * The hash of discovered test information.
@@ -56,12 +56,12 @@ class TestDiscoveryCacheContext implements CacheContextInterface {
    * @param \Drupal\Core\PrivateKey $private_key
    *   The private key service.
    * @param \Drupal\Core\Cache\CacheBackendInterface $cache
-   *   The simpletest cache.
+   *   The cache backend for TestDiscovery.
    */
   public function __construct(TestDiscovery $test_discovery, PrivateKey $private_key, CacheBackendInterface $cache) {
     $this->testDiscovery = $test_discovery;
     $this->privateKey = $private_key;
-    $this->simpletestCache = $cache;
+    $this->discoveryCache = $cache;
   }
 
   /**
@@ -79,7 +79,7 @@ public function getContext() {
       // Remove TestDiscovery's internal cache so it scans the filesystem.
       // @todo Change this for
       //   https://www.drupal.org/project/drupal/issues/1667822
-      $this->simpletestCache->delete('simpletest:discovery:classes');
+      $this->discoveryCache->delete('simpletest:discovery:classes');
       $tests = $this->testDiscovery->getTestClasses();
       $this->hash = $this->hash(serialize($tests));
     }
diff --git a/core/modules/simpletest/src/Form/SimpletestTestForm.php b/core/modules/simpletest/src/Form/SimpletestTestForm.php
index 207636a47e..a8d474fc0a 100644
--- a/core/modules/simpletest/src/Form/SimpletestTestForm.php
+++ b/core/modules/simpletest/src/Form/SimpletestTestForm.php
@@ -32,11 +32,11 @@ class SimpletestTestForm extends FormBase {
   protected $testDiscovery;
 
   /**
-   * The simpletest cache.
+   * The TestDiscovery cache.
    *
    * @var \Drupal\Core\Cache\CacheBackendInterface
    */
-  protected $simpletestCache;
+  protected $discoveryCache;
 
   /**
    * {@inheritdoc}
@@ -45,7 +45,7 @@ public static function create(ContainerInterface $container) {
     return new static(
       $container->get('renderer'),
       $container->get('test_discovery'),
-      $container->get('cache.simpletest')
+      $container->get('cache.discovery')
     );
   }
 
@@ -57,12 +57,12 @@ public static function create(ContainerInterface $container) {
    * @param \Drupal\simpletest\TestDiscovery $test_discovery
    *   The test discovery service.
    * @param \Drupal\Core\Cache\CacheBackendInterface $cache
-   *   The simpletest cache.
+   *   The TestDiscovery cache.
    */
   public function __construct(RendererInterface $renderer, TestDiscovery $test_discovery, CacheBackendInterface $cache) {
     $this->renderer = $renderer;
     $this->testDiscovery = $test_discovery;
-    $this->simpletestCache = $cache;
+    $this->discoveryCache = $cache;
   }
 
   /**
@@ -79,7 +79,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     // Clear TestDiscovery's cache. We do this to avoid a race condition within
     // the test_discovery cache context for this form.
     // @todo Change this in https://www.drupal.org/project/drupal/issues/1667822
-    $this->simpletestCache->invalidate('simpletest:discovery:classes');
+    $this->discoveryCache->invalidate('simpletest:discovery:classes');
 
     $form['#cache'] = [
       'max-age' => Cache::PERMANENT,