tests/src/Functional/JsonApiFunctionalTest.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/src/Functional/JsonApiFunctionalTest.php b/tests/src/Functional/JsonApiFunctionalTest.php
index 79a51a5..75f2bf5 100644
--- a/tests/src/Functional/JsonApiFunctionalTest.php
+++ b/tests/src/Functional/JsonApiFunctionalTest.php
@@ -464,12 +464,13 @@ class JsonApiFunctionalTest extends JsonApiFunctionalTestBase {
         ],
       ],
     ];
-    $response = $this->request('POST', $collection_url, [
+    $response = $this->request('POST', $collection_url->setOption('query', ['_format' => 'api_json']), [
       'body' => Json::encode($body),
       'auth' => [$this->user->getUsername(), $this->user->pass_raw],
       'headers' => ['Content-Type' => 'application/vnd.api+json'],
     ]);
     $created_response = Json::decode($response->getBody()->__toString());
+    var_dump($response->getBody()->__toString());
     $this->assertEquals(201, $response->getStatusCode());
     $this->assertArrayHasKey('uuid', $created_response['data']['attributes']);
     $uuid = $created_response['data']['attributes']['uuid'];