diff --git a/core/modules/jsonapi/src/Exception/EntityAccessDeniedHttpException.php b/core/modules/jsonapi/src/Exception/EntityAccessDeniedHttpException.php
index 6b067ebe6fbce0388d5952a5a3a0ec017b982589..3365326aac52fb66e9305a12c51c4f31f293b25c 100644
--- a/core/modules/jsonapi/src/Exception/EntityAccessDeniedHttpException.php
+++ b/core/modules/jsonapi/src/Exception/EntityAccessDeniedHttpException.php
@@ -30,7 +30,7 @@ class EntityAccessDeniedHttpException extends CacheableAccessDeniedHttpException
    * The error which caused the 403.
    *
    * The error contains:
-   *   - entity: The entity which the current user doens't have access to.
+   *   - entity: The entity which the current user does not have access to.
    *   - pointer: A path in the JSON:API response structure pointing to the
    *     entity.
    *   - reason: (Optional) An optional reason for this failure.
diff --git a/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalTest.php b/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalTest.php
index f5016f6e31fdc663efd836819e156babaf6ec826..b3ea1f58058a0600ebeebf8c5d7ae88db4cde2c8 100644
--- a/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalTest.php
@@ -862,7 +862,7 @@ public function testWrite() {
         'id' => $uuid,
         'type' => 'node--article',
         'attributes' => [
-          'field_that_doesnt_exist' => 'foobar',
+          'field_that_does_not_exist' => 'foobar',
         ],
       ],
     ];
@@ -876,7 +876,7 @@ public function testWrite() {
     ]);
     $updated_response = Json::decode($response->getBody()->__toString());
     $this->assertEquals(422, $response->getStatusCode());
-    $this->assertEquals("The attribute field_that_doesnt_exist does not exist on the node--article resource type.",
+    $this->assertEquals("The attribute field_that_does_not_exist does not exist on the node--article resource type.",
       $updated_response['errors']['0']['detail']);
     // 14. Successful DELETE.
     $response = $this->request('DELETE', $individual_url, [
diff --git a/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php b/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php
index 4cc441b29ae975a801f5cc9ed4865a2d33efa8f0..b7149ec5663b8852bbe1214b24dd7295b686211a 100644
--- a/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php
+++ b/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php
@@ -1118,7 +1118,7 @@ public function testCollection() {
           'related_author_id' => [
             'operator' => '<>',
             'path' => 'field_jsonapi_test_entity_ref.status',
-            'value' => 'doesnt@matter.com',
+            'value' => 'does_not@matter.com',
           ],
         ],
       ]);
diff --git a/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php b/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php
index fb7cd83551e3c126edf8feeb67bd22d7fbcb71ba..d32dd4fb2dcd4470c4bba74a9e1597dce7b935b9 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/SelectTest.php
@@ -559,7 +559,7 @@ public function testInvalidSelectCount() {
       // Normally it would throw an exception but we are suppressing
       // it with the throw_exception option.
       $options['throw_exception'] = FALSE;
-      $this->connection->select('some_table_that_doesnt_exist', 't', $options)
+      $this->connection->select('some_table_that_does_not_exist', 't', $options)
         ->fields('t')
         ->countQuery()
         ->execute();
@@ -573,7 +573,7 @@ public function testInvalidSelectCount() {
 
     try {
       // This query will fail because the table does not exist.
-      $this->connection->select('some_table_that_doesnt_exist', 't')
+      $this->connection->select('some_table_that_does_not_exist', 't')
         ->fields('t')
         ->countQuery()
         ->execute();
diff --git a/core/tests/Drupal/Tests/Component/Annotation/Doctrine/DocParserTest.php b/core/tests/Drupal/Tests/Component/Annotation/Doctrine/DocParserTest.php
index f455ea410af8ccf72cbf176d7ef308de2a6aed84..d98f8340338d54e7e819eb535994b5e8588ef7ab 100644
--- a/core/tests/Drupal/Tests/Component/Annotation/Doctrine/DocParserTest.php
+++ b/core/tests/Drupal/Tests/Component/Annotation/Doctrine/DocParserTest.php
@@ -1025,7 +1025,7 @@ public function testAnnotationDontAcceptSingleQuotes()
     /**
      * @group DCOM-41
      */
-    public function testAnnotationDoesntThrowExceptionWhenAtSignIsNotFollowedByIdentifier()
+    public function testAnnotationDoesNotThrowExceptionWhenAtSignIsNotFollowedByIdentifier()
     {
         $parser = new DocParser();
         $result = $parser->parse("'@'");
diff --git a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
index 51f02eb25373d6fb95fb7f3a5fc4b2482ed0f6ad..8f203b0f165905e9940e8e69abd7633ac541162c 100644
--- a/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php
@@ -36,7 +36,7 @@ class ChainedFastBackendTest extends UnitTestCase {
   /**
    * Tests a get() on the fast backend, with no hit on the consistent backend.
    */
-  public function testGetDoesntHitConsistentBackend() {
+  public function testGetDoesNotHitConsistentBackend() {
     $consistent_cache = $this->createMock('Drupal\Core\Cache\CacheBackendInterface');
     $timestamp_cid = ChainedFastBackend::LAST_WRITE_TIMESTAMP_PREFIX . 'cache_foo';
     // Use the request time because that is what we will be comparing against.