diff --git a/core/tests/Drupal/FunctionalTests/Datetime/TimestampTest.php b/core/tests/Drupal/FunctionalTests/Datetime/TimestampTest.php
index 4e7d989..9e79453 100644
--- a/core/tests/Drupal/FunctionalTests/Datetime/TimestampTest.php
+++ b/core/tests/Drupal/FunctionalTests/Datetime/TimestampTest.php
@@ -14,13 +14,13 @@
 /**
  * Tests the functionality of Timestamp core field UI.
  *
- * @group somegroup
+ * @group field
  */
 
 class TimestampTest extends BrowserTestBase {
 
   /**
-   * An array of display options to pass to entity_get_display()
+   * An array of display options to pass to entity_get_display().
    *
    * @var array
    */
@@ -111,6 +111,10 @@ public function testWidget() {
     // Display creation form.
     $this->drupalGet('entity_test/add');
 
+    // Make sure the "datetime_timestamp" widget is on the page.
+    $fields = $this->xpath('//div[contains(@class, "field--widget-datetime-timestamp") and @id="edit-field-timestamp-wrapper"]');
+    $this->assertEquals(1, count($fields));
+
     // Look for the widget elements and make sure they are empty.
     $this->assertSession()->fieldExists('field_timestamp[0][value][date]');
     $this->assertSession()->fieldValueEquals('field_timestamp[0][value][date]', '');
@@ -121,10 +125,10 @@ public function testWidget() {
     $date_format = DateFormat::load('html_date')->getPattern();
     $time_format = DateFormat::load('html_time')->getPattern();
 
-    $edit = array(
+    $edit = [
       'field_timestamp[0][value][date]' => $date->format($date_format),
       'field_timestamp[0][value][time]' => $date->format($time_format),
-    );
+    ];
     $this->drupalPostForm(NULL, $edit, 'Save');
 
     // Make sure the submitted date is set as the default in the widget.