diff --git a/core/tests/Drupal/Tests/Core/Test/PhpUnitBridgeTest.php b/core/tests/Drupal/Tests/Core/Test/PhpUnitBridgeTest.php
index 73ba0de167..93556ccb1a 100644
--- a/core/tests/Drupal/Tests/Core/Test/PhpUnitBridgeTest.php
+++ b/core/tests/Drupal/Tests/Core/Test/PhpUnitBridgeTest.php
@@ -21,6 +21,18 @@ public function testDeprecatedClass() {
     $this->assertEquals('test', $deprecated->testFunction());
   }
 
+  /**
+   * Tests that a PHPUnit 8 deprecation warning is converted to E_USER_DEPRECATED.
+   *
+   * @expectedDeprecation Un-skipped warning for \Drupal\Tests\Traits\PHPUnit8Warnings::$deprecationWarnings
+   *
+   * @see Drupal\Tests\Traits\PHPUnit8Warnings
+   */
+  public function testDeprecatedPhpunitMethod() {
+    $this->addWarning('Un-skipped warning for \\Drupal\\Tests\\Traits\\PHPUnit8Warnings::$deprecationWarnings');
+    $this->addToAssertionCount(1);
+  }
+
   public function testDeprecatedFunction() {
     $this->markTestIncomplete('Modules are not loaded for unit tests, so deprecated_test_function() will not be available.');
     $this->assertEquals('known_return_value', \deprecation_test_function());
diff --git a/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php b/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
index d7fb0ae246..0dcd02555b 100644
--- a/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
+++ b/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
@@ -142,6 +142,12 @@ public static function getSkippedDeprecations() {
     return [
       // The following deprecation message is skipped for testing purposes.
       '\Drupal\Tests\SkippedDeprecationTest deprecation',
+      // The following is a test PHPUnit deprecation warning re-thrown as a
+      // deprecation.
+      'Skipped warning for \\Drupal\\Tests\\Traits\\PHPUnit8Warnings::$deprecationWarnings',
+      // The following are PHPUnit 8 deprecations that need to be resolved prior
+      // to PHPUnit 9 compatibility.
+      'expectExceptionMessageRegExp() is deprecated in PHPUnit 8 and will be removed in PHPUnit 9.',
       // The following Symfony deprecations are introduced in the Symfony 4
       // development cycle. They will need to be resolved prior to Symfony 5
       // compatibility.
diff --git a/core/tests/Drupal/Tests/SkippedDeprecationTest.php b/core/tests/Drupal/Tests/SkippedDeprecationTest.php
index b65bdd22e3..65178df95c 100644
--- a/core/tests/Drupal/Tests/SkippedDeprecationTest.php
+++ b/core/tests/Drupal/Tests/SkippedDeprecationTest.php
@@ -14,6 +14,7 @@ class SkippedDeprecationTest extends UnitTestCase {
    */
   public function testSkippingDeprecations() {
     @trigger_error('\Drupal\Tests\SkippedDeprecationTest deprecation', E_USER_DEPRECATED);
+    $this->addWarning('Skipped warning for \\Drupal\\Tests\\Traits\\PHPUnit8Warnings::$deprecationWarnings');
     $this->addToAssertionCount(1);
   }
 
@@ -24,6 +25,7 @@ public function testSkippingDeprecations() {
    */
   public function testSkippingDeprecationsAgain() {
     @trigger_error('\Drupal\Tests\SkippedDeprecationTest deprecation', E_USER_DEPRECATED);
+    $this->addWarning('Skipped warning for \\Drupal\\Tests\\Traits\\PHPUnit8Warnings::$deprecationWarnings');
     $this->addToAssertionCount(1);
   }