diff --git a/core/modules/rest/tests/src/Functional/CookieResourceTestTrait.php b/core/modules/rest/tests/src/Functional/CookieResourceTestTrait.php
index c187b65..aa1bd70 100644
--- a/core/modules/rest/tests/src/Functional/CookieResourceTestTrait.php
+++ b/core/modules/rest/tests/src/Functional/CookieResourceTestTrait.php
@@ -94,6 +94,7 @@ protected function getAuthenticationRequestOptions($method) {
   protected function assertResponseWhenMissingAuthentication(ResponseInterface $response) {
     // Requests needing cookie authentication but missing it results in a 403
     // response. The cookie authentication mechanism sets no response message.
+    // @todo https://www.drupal.org/node/2847623
     $this->assertResourceErrorResponse(403, FALSE, $response);
   }
 
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestResourceTestBase.php
index 7c7836b..e6ba5bd 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestResourceTestBase.php
@@ -131,6 +131,7 @@ protected function getExpectedUnauthorizedAccessMessage($method) {
     if ($this->config('rest.settings')->get('bc_entity_resource_permissions')) {
       return parent::getExpectedUnauthorizedAccessMessage($method);
     }
+
     if ($method === 'GET') {
       return "The 'view test entity' permission is required.";
     }
diff --git a/core/modules/rest/tests/src/Functional/ResourceTestBase.php b/core/modules/rest/tests/src/Functional/ResourceTestBase.php
index a7dacac..2674d70 100644
--- a/core/modules/rest/tests/src/Functional/ResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/ResourceTestBase.php
@@ -210,7 +210,7 @@ protected function provisionResource($resource_type, $formats = [], $authenticat
    *   The HTTP method (GET, POST, PATCH, DELETE).
    *
    * @return string
-   *    The Error string.
+   *    The error string.
    */
   abstract protected function getExpectedUnauthorizedAccessMessage($method);
 
@@ -222,7 +222,7 @@ protected function provisionResource($resource_type, $formats = [], $authenticat
    *   The HTTP method (GET, POST, PATCH, DELETE).
    *
    * @return string
-   *   The Error string.
+   *   The error string.
    */
   abstract protected function getExpectedBcUnauthorizedAccessMessage($method);
 
diff --git a/core/tests/Drupal/Tests/Core/Access/AccessResultNeutralTest.php b/core/tests/Drupal/Tests/Core/Access/AccessResultNeutralTest.php
index e96ba29..5b96b19 100644
--- a/core/tests/Drupal/Tests/Core/Access/AccessResultNeutralTest.php
+++ b/core/tests/Drupal/Tests/Core/Access/AccessResultNeutralTest.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\Tests\Core\Access;
 
-use Drupal\Core\Access\AccessResultForbidden;
 use Drupal\Core\Access\AccessResultNeutral;
 use Drupal\Tests\UnitTestCase;
 
@@ -19,9 +18,8 @@ class AccessResultNeutralTest extends UnitTestCase {
    * @covers ::getReason
    */
   public function testConstruction() {
-
     $a = new AccessResultNeutral();
-    $this->assertEquals(NULL, $a->getReason());
+    $this->assertNull($a->getReason());
 
     $reason = $this->getRandomGenerator()->string();
     $b = new AccessResultNeutral($reason);
diff --git a/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php b/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php
index 487ab0e..6f18648 100644
--- a/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php
+++ b/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php
@@ -174,9 +174,9 @@ public function testAccessConditionallyForbidden() {
    * @covers ::andIf
    */
   public function testAndIf() {
-    $neutral = AccessResult::neutral();
+    $neutral = AccessResult::neutral('neutral message');
     $allowed = AccessResult::allowed();
-    $forbidden = AccessResult::forbidden();
+    $forbidden = AccessResult::forbidden('forbidden message');
     $unused_access_result_due_to_lazy_evaluation = $this->getMock('\Drupal\Core\Access\AccessResultInterface');
     $unused_access_result_due_to_lazy_evaluation->expects($this->never())
       ->method($this->anything());
@@ -193,6 +193,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertFalse($access->isForbidden());
     $this->assertTrue($access->isNeutral());
+    $this->assertEquals('neutral message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // ALLOWED && FORBIDDEN === FORBIDDEN.
@@ -200,6 +201,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // NEUTRAL && ALLOW == NEUTRAL
@@ -207,6 +209,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertFalse($access->isForbidden());
     $this->assertTrue($access->isNeutral());
+    $this->assertEquals('neutral message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // NEUTRAL && NEUTRAL === NEUTRAL.
@@ -214,6 +217,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertFalse($access->isForbidden());
     $this->assertTrue($access->isNeutral());
+    $this->assertEquals('neutral message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // NEUTRAL && FORBIDDEN === FORBIDDEN.
@@ -221,6 +225,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN && ALLOWED = FORBIDDEN
@@ -228,6 +233,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN && NEUTRAL = FORBIDDEN
@@ -235,6 +241,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN && FORBIDDEN = FORBIDDEN
@@ -242,6 +249,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN && * === FORBIDDEN: lazy evaluation verification.
@@ -249,6 +257,7 @@ public function testAndIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
   }
 
@@ -256,9 +265,9 @@ public function testAndIf() {
    * @covers ::orIf
    */
   public function testOrIf() {
-    $neutral = AccessResult::neutral();
+    $neutral = AccessResult::neutral('neutral message');
     $allowed = AccessResult::allowed();
-    $forbidden = AccessResult::forbidden();
+    $forbidden = AccessResult::forbidden('forbidden message');
     $unused_access_result_due_to_lazy_evaluation = $this->getMock('\Drupal\Core\Access\AccessResultInterface');
     $unused_access_result_due_to_lazy_evaluation->expects($this->never())
       ->method($this->anything());
@@ -282,6 +291,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // NEUTRAL || NEUTRAL === NEUTRAL.
@@ -289,6 +299,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertFalse($access->isForbidden());
     $this->assertTrue($access->isNeutral());
+    $this->assertEquals('neutral message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // NEUTRAL || ALLOWED === ALLOWED.
@@ -303,6 +314,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN || ALLOWED === FORBIDDEN.
@@ -310,6 +322,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN || NEUTRAL === FORBIDDEN.
@@ -317,6 +330,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN || FORBIDDEN === FORBIDDEN.
@@ -324,6 +338,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
 
     // FORBIDDEN || * === FORBIDDEN.
@@ -331,6 +346,7 @@ public function testOrIf() {
     $this->assertFalse($access->isAllowed());
     $this->assertTrue($access->isForbidden());
     $this->assertFalse($access->isNeutral());
+    $this->assertEquals('forbidden message', $access->getReason());
     $this->assertDefaultCacheability($access);
   }