jsonapi.services.yml                               | 13 +++++++----
 ...ported.php => RestJsonApiFormatUnsupported.php} | 27 +++++++++-------------
 2 files changed, 19 insertions(+), 21 deletions(-)

diff --git a/jsonapi.services.yml b/jsonapi.services.yml
index 0b47f98..ecd6c36 100644
--- a/jsonapi.services.yml
+++ b/jsonapi.services.yml
@@ -98,11 +98,14 @@ services:
       - { name: event_subscriber }
     arguments: ['@jsonapi.serializer', '%serializer.formats%']
 
-  # We want the 'api_json' format to not be supported in the REST module, so we cannot register its encoder with the
-  # Serialization module. Hence we have an encoder without the 'encoder' tag and 'format' property. But that also means
-  # we cannot reuse the @serializer service. So we define our own serializer service. But we still do want to reuse the
-  # generic normalizers from the Serialization module. So we inject all normalizers just like the default @serializer
-  # service does. Only appropriate normalizers are called thanks to the supportsNormalization() API method.
+  # We want the 'api_json' format to not be supported in the REST module, so we
+  # cannot register its encoder with the Serialization module. Hence we have an
+  # encoder without the 'encoder' tag and 'format' property. But that also
+  # means we cannot reuse the @serializer service. So we define our own
+  # serializer service. But we still do want to reuse the generic normalizers
+  # from the Serialization module. So we inject all normalizers just like the
+  # default @serializer service does. Only appropriate normalizers are called
+  # thanks to the supportsNormalization() API method.
   # @see \Drupal\jsonapi\DependencyInjection\Compiler\RegisterNormalizerClassesCompilerPass
   # @see \Drupal\jsonapi\JsonapiServiceProvider::register()
   # @see \Drupal\Tests\jsonapi\Functional\RestJsonApiUnsupported
diff --git a/tests/src/Functional/RestJsonApiUnsupported.php b/tests/src/Functional/RestJsonApiFormatUnsupported.php
similarity index 76%
rename from tests/src/Functional/RestJsonApiUnsupported.php
rename to tests/src/Functional/RestJsonApiFormatUnsupported.php
index 18e0878..1c7d783 100644
--- a/tests/src/Functional/RestJsonApiUnsupported.php
+++ b/tests/src/Functional/RestJsonApiFormatUnsupported.php
@@ -12,7 +12,7 @@ use Drupal\Tests\rest\Functional\ResourceTestBase;
 /**
  * @group jsonapi
  */
-class RestJsonApiUnsupported extends ResourceTestBase {
+class RestJsonApiFormatUnsupported extends ResourceTestBase {
 
   use AnonResourceTestTrait;
 
@@ -35,13 +35,7 @@ class RestJsonApiUnsupported extends ResourceTestBase {
    * {@inheritdoc}
    */
   protected function setUpAuthorization($method) {
-    switch ($method) {
-      case 'GET':
-        $this->grantPermissionsToTestedRole(['access content']);
-        break;
-      default:
-        throw new \UnexpectedValueException();
-    }
+    $this->grantPermissionsToTestedRole(['access content']);
   }
 
   /**
@@ -69,19 +63,20 @@ class RestJsonApiUnsupported extends ResourceTestBase {
   }
 
   /**
-   * Deploying a REST resource using api_json format results in 406 responses.
+   * Tests that JSON API is not supported
    */
-  public function testApiJsonNotSupportedInRest() {
+  public function testJsonApiFormatNotSupportedInRest() {
+    // First, verify that 'api_json' does not appear in the 'serializer.foramts'
+    // container parameter, which is what the REST module uses to determine
+    // which formats it supports.
     $this->assertSame(['json', 'xml'], $this->container->getParameter('serializer.formats'));
 
+    // Second, verify that provisioning a REST resource that lists 'api_json' as
+    // one of its formats
     $this->provisionResource('entity.node', ['api_json'], []);
     $this->setUpAuthorization('GET');
-
-    $url = Node::load(1)->toUrl()
-      ->setOption('query', ['_format' => 'api_json']);
-    $request_options = [];
-
-    $response = $this->request('GET', $url, $request_options);
+    $url = Node::load(1)->toUrl()->setOption('query', ['_format' => 'api_json']);
+    $response = $this->request('GET', $url, []);
     $expected_body = Json::encode([
       'errors' => [
         [