--- /dev/null
+<?php
+
+namespace Drupal\Tests\file\Functional\Formatter;
+
+use Drupal\entity_test\Entity\EntityTest;
+use Drupal\file\Entity\File;
+
+/**
+ * @coversDefaultClass \Drupal\file\Plugin\Field\FieldFormatter\FileVideoFormatter
+ * @group file
+ */
+class FileVideoFormatterTest extends FileMediaFormatterTestBase {
+
+ /**
+ * @covers ::viewElements
+ *
+ * @dataProvider dataProvider
+ */
+ public function testRender($tag_count, $formatter_settings) {
+ $field_config = $this->createMediaField('file_video', 'mp4', $formatter_settings);
+
+ file_put_contents('public://file.mp4', str_repeat('t', 10));
+ $file1 = File::create([
+ 'uri' => 'public://file.mp4',
+ 'filename' => 'file.mp4',
+ ]);
+ $file1->save();
+
+ $file2 = File::create([
+ 'uri' => 'public://file.mp4',
+ 'filename' => 'file.mp4',
+ ]);
+ $file2->save();
+
+ $entity = EntityTest::create([
+ $field_config->getName() => [
+ [
+ 'target_id' => $file1->id(),
+ ],
+ [
+ 'target_id' => $file2->id(),
+ ],
+ ],
+ ]);
+ $entity->save();
+
+ $this->drupalGet($entity->toUrl());
+
+ $file1_url = file_url_transform_relative(file_create_url($file1->getFileUri()));
+ $file2_url = file_url_transform_relative(file_create_url($file2->getFileUri()));
+
+ $assert_session = $this->assertSession();
+ $assert_session->elementsCount('css', 'video[controls="controls"]', $tag_count);
+ $assert_session->elementExists('css', "video > source[src='$file1_url'][type='video/mp4']");
+ $assert_session->elementExists('css', "video > source[src='$file2_url'][type='video/mp4']");
+ }
+
+}