diff --git a/core/modules/media/tests/src/FunctionalJavascript/MediaSourceAudioVideoTest.php b/core/modules/media/tests/src/FunctionalJavascript/MediaSourceAudioVideoTest.php
index 3b53952..218821a 100644
--- a/core/modules/media/tests/src/FunctionalJavascript/MediaSourceAudioVideoTest.php
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaSourceAudioVideoTest.php
@@ -5,6 +5,7 @@
 use Drupal\Core\Entity\Entity\EntityViewDisplay;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\file\Entity\File;
 
 /**
  * Tests the Audio and Video media sources.
@@ -17,6 +18,9 @@ class MediaSourceAudioVideoTest extends MediaSourceTestBase {
    * Check the Local Audio source functionality.
    */
   public function testAudioTypeCreation() {
+    $assert_session = $this->assertSession();
+    $page = $this->getSession()->getPage();
+
     $source_id = 'file_audio';
     $type_name = 'audio_type';
     $field_name = 'field_media_' . $source_id;
@@ -34,12 +38,33 @@ public function testAudioTypeCreation() {
     $this->assertNotNull($display);
     $formatter = $display->getComponent($field_name)['type'];
     $this->assertSame('file_audio', $formatter);
+
+    // Create a media asset and verify that the <audio> tag is present.
+    file_put_contents('public://file.mp3', str_repeat('t', 10));
+    $file = File::create([
+      'uri' => 'public://file.mp3',
+      'filename' => 'file.mp3',
+    ]);
+    $file->save();
+
+    $this->drupalGet("media/add/$type_name");
+    $page->fillField('Name', 'Audio media asset');
+    $page->attachFileToField("files[{$field_name}_0]", \Drupal::service('file_system')->realpath('public://file.mp3'));
+    $result = $assert_session->waitForButton('Remove');
+    $this->assertNotEmpty($result);
+    $page->pressButton('Save');
+
+    $assert_session->pageTextContains("$type_name Audio media asset has been created.");
+    $assert_session->elementExists('css', "audio > source[type='audio/mpeg']");
   }
 
   /**
    * Check the Local Video source functionality.
    */
   public function testVideoTypeCreation() {
+    $assert_session = $this->assertSession();
+    $page = $this->getSession()->getPage();
+
     $source_id = 'file_video';
     $type_name = 'video_type';
     $field_name = 'field_media_' . $source_id;
@@ -57,6 +82,24 @@ public function testVideoTypeCreation() {
     $this->assertNotNull($display);
     $formatter = $display->getComponent($field_name)['type'];
     $this->assertSame('file_video', $formatter);
+
+    // Create a media asset and verify that the <video> tag is present.
+    file_put_contents('public://file.mp4', str_repeat('t', 10));
+    $file = File::create([
+      'uri' => 'public://file.mp4',
+      'filename' => 'file.mp4',
+    ]);
+    $file->save();
+
+    $this->drupalGet("media/add/$type_name");
+    $page->fillField('Name', 'Video media asset');
+    $page->attachFileToField("files[{$field_name}_0]", \Drupal::service('file_system')->realpath('public://file.mp4'));
+    $result = $assert_session->waitForButton('Remove');
+    $this->assertNotEmpty($result);
+    $page->pressButton('Save');
+
+    $assert_session->pageTextContains("$type_name Video media asset has been created.");
+    $assert_session->elementExists('css', "video > source[type='video/mp4']");
   }
 
 }