.../EntityTestTextItemNormalizerTest.php           | 63 +++++++++++++++++++---
 .../EntityResource/Term/TermResourceTestBase.php   |  6 +--
 2 files changed, 60 insertions(+), 9 deletions(-)

diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestTextItemNormalizerTest.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestTextItemNormalizerTest.php
index 336bd58..b41ad7f 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestTextItemNormalizerTest.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestTextItemNormalizerTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\rest\Functional\EntityResource\EntityTest;
 
 use Drupal\Core\Cache\Cache;
+use Drupal\Core\Language\LanguageInterface;
 use Drupal\filter\Entity\FilterFormat;
 use Drupal\Tests\rest\Functional\AnonResourceTestTrait;
 
@@ -16,6 +17,11 @@ class EntityTestTextItemNormalizerTest extends EntityTestResourceTestBase {
   /**
    * {@inheritdoc}
    */
+  public static $modules = ['filter_test'];
+
+  /**
+   * {@inheritdoc}
+   */
   protected static $format = 'json';
 
   /**
@@ -31,8 +37,8 @@ protected function getExpectedNormalizedEntity() {
     $expected['field_test_text'] = [
       [
         'value' => 'Cádiz is the oldest continuously inhabited city in Spain and a nice place to spend a Sunday with friends.',
-        'format' => 'plain_text',
-        'processed' => '<p>Cádiz is the oldest continuously inhabited city in Spain and a nice place to spend a Sunday with friends.</p>' . "\n",
+        'format' => 'my_text_format',
+        'processed' => '<p>Cádiz is the oldest continuously inhabited city in Spain and a nice place to spend a Sunday with friends.</p>' . "\n" . '<p>This is a dynamic llama.</p>',
       ],
     ];
     return $expected;
@@ -43,9 +49,38 @@ protected function getExpectedNormalizedEntity() {
    */
   protected function createEntity() {
     $entity = parent::createEntity();
+    FilterFormat::create([
+      'format' => 'my_text_format',
+      'name' => 'My Text Format',
+      'filters' => [
+        'filter_test_assets' => [
+          'weight' => -1,
+          'status' => TRUE,
+        ],
+        'filter_test_cache_tags' => [
+          'weight' => 0,
+          'status' => TRUE,
+        ],
+        'filter_test_cache_contexts' => [
+          'weight' => 0,
+          'status' => TRUE,
+        ],
+        'filter_test_cache_merge' => [
+          'weight' => 0,
+          'status' => TRUE,
+        ],
+        'filter_test_placeholders' => [
+          'weight' => 1,
+          'status' => TRUE,
+        ],
+        'filter_autop' => [
+          'status' => TRUE,
+        ],
+      ],
+    ])->save();
     $entity->field_test_text = [
       'value' => 'Cádiz is the oldest continuously inhabited city in Spain and a nice place to spend a Sunday with friends.',
-      'format' => 'plain_text',
+      'format' => 'my_text_format',
     ];
     $entity->save();
     return $entity;
@@ -59,7 +94,7 @@ protected function getNormalizedPostEntity() {
     $post_entity['field_test_text'] = [
       [
         'value' => 'Llamas are awesome.',
-        'format' => 'plain_text',
+        'format' => 'my_text_format',
       ],
     ];
     return $post_entity;
@@ -69,14 +104,30 @@ protected function getNormalizedPostEntity() {
    * {@inheritdoc}
    */
   protected function getExpectedCacheTags() {
-    return Cache::mergeTags(['config:filter.format.plain_text'], parent::getExpectedCacheTags());
+    return Cache::mergeTags([
+      // The cache tag set by the processed_text element itself.
+      'config:filter.format.my_text_format',
+      // The cache tags set by the filter_test_cache_tags filter.
+      'foo:bar',
+      'foo:baz',
+      // The cache tags set by the filter_test_cache_merge filter.
+      'merge:tag'
+    ], parent::getExpectedCacheTags());
   }
 
   /**
    * {@inheritdoc}
    */
   protected function getExpectedCacheContexts() {
-    return Cache::mergeContexts(['languages:language_interface', 'theme'], parent::getExpectedCacheContexts());
+    return Cache::mergeContexts([
+      // The cache context set by the filter_test_cache_contexts filter.
+      'languages:' . LanguageInterface::TYPE_CONTENT,
+      // The default cache contexts for Renderer.
+      'languages:' . LanguageInterface::TYPE_INTERFACE,
+      'theme',
+      // The cache tags set by the filter_test_cache_merge filter.
+      'user.permissions',
+    ], parent::getExpectedCacheContexts());
   }
 
   /**
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/Term/TermResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/Term/TermResourceTestBase.php
index b34fb52..713c1e5 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/Term/TermResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/Term/TermResourceTestBase.php
@@ -80,7 +80,7 @@ protected function createEntity() {
     // Create a "Llama" taxonomy term.
     $term = Term::create(['vid' => $vocabulary->id()])
       ->setName('Llama')
-      ->setDescription("It is a little known fact that llamas cannot count higher the seven.")
+      ->setDescription("It is a little known fact that llamas cannot count higher than seven.")
       ->setChangedTime(123456789)
       ->set('path', '/llama');
     $term->save();
@@ -111,9 +111,9 @@ protected function getExpectedNormalizedEntity() {
       ],
       'description' => [
         [
-          'value' => 'It is a little known fact that llamas cannot count higher the seven.',
+          'value' => 'It is a little known fact that llamas cannot count higher than seven.',
           'format' => NULL,
-          'processed' => "<p>It is a little known fact that llamas cannot count higher the seven.</p>\n",
+          'processed' => "<p>It is a little known fact that llamas cannot count higher than seven.</p>\n",
         ],
       ],
       'parent' => [],