diff -u b/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php b/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php
--- b/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php
+++ b/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php
@@ -66,7 +66,7 @@
     $dependencies['config'] = array_merge($config, $format_dependencies);
     return $dependencies;
   }
-  
+
   /**
    * {@inheritdoc}
    */
diff -u b/core/modules/text/tests/src/Functional/TextFieldTest.php b/core/modules/text/tests/src/Functional/TextFieldTest.php
--- b/core/modules/text/tests/src/Functional/TextFieldTest.php
+++ b/core/modules/text/tests/src/Functional/TextFieldTest.php
@@ -163,7 +163,8 @@
       'format' => mb_strtolower($this->randomMachineName()),
       'name' => $this->randomMachineName(),
     ];
-    $this->drupalPostForm('admin/config/content/formats/add', $edit, t('Save configuration'));
+    $this->drupalGet('admin/config/content/formats/add');
+    $this->submitForm($edit, 'Save configuration');
     filter_formats_reset();
     /** @var \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager */
     $entity_type_manager = $this->container->get('entity_type.manager');
@@ -177,7 +178,8 @@
       'format' => mb_strtolower($this->randomMachineName()),
       'name' => $this->randomMachineName(),
     ];
-    $this->drupalPostForm('admin/config/content/formats/add', $edit, t('Save configuration'));
+    $this->drupalGet('admin/config/content/formats/add');
+    $this->submitForm($edit, 'Save configuration');
     filter_formats_reset();
     /** @var \Drupal\filter\Entity\FilterFormat $format2 */
     $format2 = $filter_format_storage->load($edit['format']);
@@ -230,7 +232,7 @@
     // We shouldn't have the 'format' selector since only one format is allowed.
     $this->drupalGet('entity_test/add');
     $this->assertSession()->fieldExists("{$field_name}[0][value]", NULL);
-    $this->assertNoFieldByName("{$field_name}[0][format]", NULL, 'Format selector is not displayed');
+    $this->assertSession()->fieldNotExists("{$field_name}[0][format]");
 
     // Change field to allow all formats by configuring none as allowed.
     $field->setSetting('allowed_formats', []);