diff --git a/core/modules/system/tests/src/Functional/Theme/ThemeLegacyTest.php b/core/modules/system/tests/src/Functional/Theme/ThemeLegacyTest.php
index 7de359c95b..f7b0cbfe46 100644
--- a/core/modules/system/tests/src/Functional/Theme/ThemeLegacyTest.php
+++ b/core/modules/system/tests/src/Functional/Theme/ThemeLegacyTest.php
@@ -33,6 +33,8 @@ protected function setUp(): void {
 
   /**
    * Ensures a theme template can override a theme function.
+   *
+   * @expectedDeprecation Theme functions are deprecated in drupal:8.0.0 and are removed from drupal:10.0.0. Use Twig templates instead of theme_theme_test_render_element_children(). See https://www.drupal.org/node/1831138
    */
   public function testFunctionOverride() {
     $this->drupalGet('theme-test/function-template-overridden');
@@ -41,6 +43,8 @@ public function testFunctionOverride() {
 
   /**
    * Tests that theme suggestion alter hooks work for theme functions.
+   *
+   * @expectedDeprecation Theme functions are deprecated in drupal:8.0.0 and are removed from drupal:10.0.0. Use Twig templates instead of theme_theme_test_render_element_children(). See https://www.drupal.org/node/1831138
    */
   public function testThemeFunctionSuggestionsAlter() {
     $this->drupalGet('theme-test/function-suggestion-alter');
@@ -63,6 +67,8 @@ public function testThemeFunctionSuggestionsAlter() {
 
   /**
    * Tests that theme suggestion alter hooks work with theme hook includes.
+   *
+   * @expectedDeprecation Theme functions are deprecated in drupal:8.0.0 and are removed from drupal:10.0.0. Use Twig templates instead of theme_theme_test_render_element_children(). See https://www.drupal.org/node/1831138
    */
   public function testSuggestionsAlterInclude() {
     // Check the original theme output.
diff --git a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
index d6d8e44246..897a07dfd2 100644
--- a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -799,6 +799,7 @@ public function testEscapingAssertions() {
   /**
    * Tests that deprecation headers do not get duplicated.
    *
+   * @expectedDeprecation Test deprecation message
    * @group legacy
    *
    * @see \Drupal\Core\Test\HttpClientMiddleware\TestHttpClientMiddleware::__invoke()
diff --git a/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php b/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
index f28f28f92e..3de5673ee4 100644
--- a/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
+++ b/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
@@ -209,8 +209,19 @@ protected function registerErrorHandler() {
     }
     $deprecation_handler = function ($type, $msg, $file, $line, $context = []) {
       // Skip listed deprecations.
-      if ($type === E_USER_DEPRECATED && static::isDeprecationSkipped($msg)) {
-        return;
+      if ($type === E_USER_DEPRECATED) {
+        $message = $msg;
+        // @todo long and winding comment.
+        if (strpos($message, 'a:') === 0) {
+          $deprecation_array = @unserialize($message, ['allowed_classes' => FALSE]);
+          if (isset($deprecation_array['deprecation'])) {
+            $message = $deprecation_array['deprecation'];
+          }
+        }
+
+        if (static::isDeprecationSkipped($message)) {
+          return;
+        }
       }
       return call_user_func($this->previousHandler, $type, $msg, $file, $line, $context);
     };
diff --git a/core/tests/Drupal/Tests/Listeners/DrupalListener.php b/core/tests/Drupal/Tests/Listeners/DrupalListener.php
index 04254b24c3..5a70cfe637 100644
--- a/core/tests/Drupal/Tests/Listeners/DrupalListener.php
+++ b/core/tests/Drupal/Tests/Listeners/DrupalListener.php
@@ -6,7 +6,7 @@
 use PHPUnit\Framework\TestListenerDefaultImplementation;
 use PHPUnit\Framework\Test;
 use PHPUnit\Framework\TestSuite;
-use Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerTrait;
+use Symfony\Bridge\PhpUnit\SymfonyTestsListener;
 
 /**
  * Listens to PHPUnit test runs.
@@ -36,22 +36,22 @@ class DrupalListener implements TestListener {
   ];
 
   /**
-   * @var \Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerTrait
+   * @var \Symfony\Bridge\PhpUnit\SymfonyTestsListener
    */
-  private $symfonyTrait;
+  private $symfonyListener;
 
   /**
    * {@inheritdoc}
    */
   public function __construct() {
-    $this->symfonyTrait = new SymfonyTestsListenerTrait();
+    $this->symfonyListener = new SymfonyTestsListener();
   }
 
   /**
    * {@inheritdoc}
    */
   public function startTestSuite(TestSuite $suite): void {
-    $this->symfonyTrait->startTestSuite($suite);
+    $this->symfonyListener->startTestSuite($suite);
     $this->registerErrorHandler();
   }
 
@@ -59,7 +59,7 @@ public function startTestSuite(TestSuite $suite): void {
    * {@inheritdoc}
    */
   public function addSkippedTest(Test $test, \Throwable $t, float $time): void {
-    $this->symfonyTrait->addSkippedTest($test, $t, $time);
+    $this->symfonyListener->addSkippedTest($test, $t, $time);
   }
 
   /**
@@ -68,7 +68,7 @@ public function addSkippedTest(Test $test, \Throwable $t, float $time): void {
   public function startTest(Test $test): void {
     $this->registerErrorHandler();
     $this->deprecationStartTest($test);
-    $this->symfonyTrait->startTest($test);
+    $this->symfonyListener->startTest($test);
 
     // Check for missing void return typehints in concrete test classes'
     // methods. If the method is inherited from a base test class, do
@@ -91,10 +91,20 @@ public function startTest(Test $test): void {
    */
   public function endTest(Test $test, float $time): void {
     $this->deprecationEndTest($test, $time);
-    $this->symfonyTrait->endTest($test, $time);
+    $this->symfonyListener->endTest($test, $time);
     $this->componentEndTest($test, $time);
     $this->standardsEndTest($test, $time);
     $this->removeErrorHandler();
   }
 
+  /**
+   * Gets the wrapped symfony listener.
+   *
+   * @return \Symfony\Bridge\PhpUnit\SymfonyTestsListener
+   *   The Symfony test listener.
+   */
+  public function getSymfonyTestListener() {
+    return $this->symfonyListener;
+  }
+
 }
diff --git a/core/tests/Drupal/Tests/Traits/ExpectDeprecationTrait.php b/core/tests/Drupal/Tests/Traits/ExpectDeprecationTrait.php
index 0aab5cade2..e9bff32fd3 100644
--- a/core/tests/Drupal/Tests/Traits/ExpectDeprecationTrait.php
+++ b/core/tests/Drupal/Tests/Traits/ExpectDeprecationTrait.php
@@ -100,10 +100,11 @@ private function getSymfonyTestListenerTrait() {
     $listeners = $reflection_property->getValue($test_result_object);
     foreach ($listeners as $listener) {
       if ($listener instanceof DrupalListener) {
-        $reflection_class = new \ReflectionClass($listener);
-        $reflection_property = $reflection_class->getProperty('symfonyTrait');
+        $sf_listener = $listener->getSymfonyTestListener();
+        $reflection_class = new \ReflectionClass($sf_listener);
+        $reflection_property = $reflection_class->getProperty('trait');
         $reflection_property->setAccessible(TRUE);
-        return $reflection_property->getValue($listener);
+        return $reflection_property->getValue($sf_listener);
       }
     }
   }