diff --git a/core/lib/Drupal/Core/Test/EnvironmentCleaner.php b/core/lib/Drupal/Core/Test/EnvironmentCleaner.php
index 23976b666c..31da3cfc07 100644
--- a/core/lib/Drupal/Core/Test/EnvironmentCleaner.php
+++ b/core/lib/Drupal/Core/Test/EnvironmentCleaner.php
@@ -7,7 +7,7 @@
 use Symfony\Component\Console\Output\OutputInterface;
 
 /**
- * Clean up after tests.
+ * Helper class for cleaning test environments.
  */
 class EnvironmentCleaner implements EnvironmentCleanerInterface {
 
@@ -29,6 +29,8 @@ class EnvironmentCleaner implements EnvironmentCleanerInterface {
    * Connection to the database where test results are stored.
    *
    * This could be the same as $testDatabase, or it could be different.
+   * run-tests.sh allows you to specify a different results database with the
+   * --sqlite parameter.
    *
    * @var \Drupal\Core\Database\Connection
    */
@@ -42,6 +44,7 @@ class EnvironmentCleaner implements EnvironmentCleanerInterface {
   protected $fileSystem;
 
   /**
+   * Console output.
    *
    * @var \Symfony\Component\Console\Output\OutputInterface
    */
@@ -104,6 +107,7 @@ public function cleanDatabase() {
   }
 
   /**
+   * Performs the fixture database cleanup.
    *
    * @return int
    *   The number of tables that were removed.
@@ -138,6 +142,7 @@ public function cleanTemporaryDirectories() {
   }
 
   /**
+   * Performs the cleanup of temporary test directories.
    *
    * @return int
    *   The count of temporary directories removed.
diff --git a/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
index 947828f2ec..a2ee22a6b9 100644
--- a/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -658,12 +658,13 @@ function simpletest_clean_temporary_directories() {
  */
 function simpletest_clean_results_table($test_id = NULL) {
   @trigger_error(__FUNCTION__ . ' is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Access the environment_cleaner service and call its cleanResultsTable() method, or use \Drupal\Core\Test\EnvironmentCleaner::cleanResultsTable() instead. See https://www.drupal.org/node/3076634', E_USER_DEPRECATED);
+  $count = 0;
   if (\Drupal::config('simpletest.settings')->get('clear_results')) {
     /* @var $cleaner \Drupal\simpletest\EnvironmentCleanerService */
     $cleaner = \Drupal::service('environment_cleaner');
-    $cleaner->cleanResultsTable($test_id);
+    $count = $cleaner->cleanResultsTable($test_id);
   }
-  return 0;
+  return $count;
 }
 
 /**
diff --git a/core/modules/simpletest/simpletest.services.yml b/core/modules/simpletest/simpletest.services.yml
index cede4646b5..afae7c4358 100644
--- a/core/modules/simpletest/simpletest.services.yml
+++ b/core/modules/simpletest/simpletest.services.yml
@@ -1,17 +1,13 @@
 services:
   test_discovery:
-    # Drupal\simpletest\TestDiscovery is deprecated, but we still want to use it
-    # as the service here to support BC hooks.
     class: Drupal\simpletest\TestDiscovery
     arguments: ['@app.root', '@class_loader', '@module_handler']
-
   environment_cleaner_factory:
     class: Drupal\simpletest\EnvironmentCleanerFactory
     arguments: ['@service_container']
   environment_cleaner:
     class: Drupal\simpletest\EnvironmentCleanerService
     factory: 'environment_cleaner_factory:createCleaner'
-
   cache_context.test_discovery:
     class: Drupal\simpletest\Cache\Context\TestDiscoveryCacheContext
     arguments: ['@test_discovery', '@private_key']
diff --git a/core/modules/simpletest/tests/src/Kernel/DeprecatedCleanupTest.php b/core/modules/simpletest/tests/src/Kernel/DeprecatedCleanupTest.php
index a5efa34a1e..ec29a76768 100644
--- a/core/modules/simpletest/tests/src/Kernel/DeprecatedCleanupTest.php
+++ b/core/modules/simpletest/tests/src/Kernel/DeprecatedCleanupTest.php
@@ -36,7 +36,7 @@ public function testDeprecatedCleanFunctions() {
     $this->assertNull(simpletest_clean_environment());
     $this->assertNull(simpletest_clean_database());
     $this->assertNull(simpletest_clean_temporary_directories());
-    $this->assertNull(simpletest_clean_results_table());
+    $this->assertEquals(0, simpletest_clean_results_table());
   }
 
 }