diff --git a/core/modules/file/tests/src/FunctionalJavascript/ClientValidationTest.php b/core/modules/file/tests/src/FunctionalJavascript/ClientValidationTest.php
index 82ee052..e2bb136 100644
--- a/core/modules/file/tests/src/FunctionalJavascript/ClientValidationTest.php
+++ b/core/modules/file/tests/src/FunctionalJavascript/ClientValidationTest.php
@@ -3,6 +3,8 @@
 namespace Drupal\Tests\file\FunctionalJavascript;
 
 use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+use Drupal\image\Tests\ImageFieldCreationTrait;
+
 
 /**
  * Tests the client side JavaScript validation.
@@ -11,10 +13,12 @@
  */
 class ClientValidationTest extends JavascriptTestBase {
 
+  use ImageFieldCreationTrait;
+
   /**
    * {@inheritdoc}
    */
-  public static $modules = ['file', 'node'];
+  public static $modules = ['node', 'image', 'field_ui'];
 
 
   /**
@@ -29,6 +33,30 @@ class ClientValidationTest extends JavascriptTestBase {
    */
   protected function setUp() {
     parent::setUp();
+
+    // Create the Article node type.
+    $this->drupalCreateContentType(['type' => 'article', 'name' => 'Article']);
+
+    // Create a field with a basic filetype restriction.
+    $field_name = strtolower($this->randomMachineName());
+    $field_settings = [
+      'file_extensions' => 'png',
+    ];
+    $formatter_settings = [
+      'image_style' => 'large',
+      'image_link' => '',
+    ];
+    $this->createImageField($field_name, 'article', [], $field_settings, [], $formatter_settings);
+
+    // Log in as a content author who can create Articles.
+    $user = $this->drupalCreateUser([
+      'access content',
+      'create article content',
+      'edit any article content',
+      'delete any article content',
+    ]);
+    $this->drupalLogin($user);
+
     $uri = 'public://file.txt';
     file_unmanaged_save_data('Drupal rocks!', $uri, FILE_EXISTS_REPLACE);
     $this->file_path = \Drupal::service('file_system')->realpath($uri);
@@ -38,27 +66,28 @@ protected function setUp() {
    * Tests the client side validation on file fields.
    */
   public function testDisallowedExtensionErrorMessage() {
-    $admin_user = $this->drupalCreateUser([
-      'administer site configuration',
-    ]);
-    $this->drupalLogin($admin_user);
-
     $this->drupalGet('node/add/article');
+    $assert = $this->assertSession();
 
     // Test uploading a file with a file extension not allowed.
     // Try to upload a file with an unallowed extension
-    $file_path = $this->file_path;
-    $session = $this->getSession();
-    $session->executeScript("page.uploadFile('input[name=files[field_image_0]]', $file_path);");
+    $input_selector = 'input.form-file';
+    $input = $assert->elementExists('css', $input_selector);
+    $input->attachFile($this->file_path);
+
+    // Trigger the upload logic with a mock "drop" event.
+    $script = 'var e = jQuery.Event("drop");'
+      . 'e.originalEvent = {dataTransfer: {files: jQuery("input.form-file").get(0).files}};'
+      . 'e.preventDefault = e.stopPropagation = function () {};'
+      . 'jQuery("input.form-file").trigger(e);';
+    $this->getSession()->executeScript($script);
 
     // Verify that the error message is there.
     $error_selector = '.file-upload-js-error';
-    $assert = $this->assertSession();
+    // Verify that there is one and only one error message on the page.
+    $condition = "jQuery('$error_selector').length == 1";
+    $this->assertJsCondition($condition, 10000);
     $assert->elementExists('css', $error_selector);
-    $assert->elementContains('css', $error_selector, 'The selected file robots.txt cannot be uploaded. Only files with the following extensions are allowed: png, gif, jpg, jpeg.');
-    // Verify that there is only one error message on the page.
-    $condition = "(jQuery('$error_selector').length == 1)";
-    $assert->assertJsCondition($condition);
   }
 
 }