Use array assertions in tests

tests/src/Functional/JsonApiImageStylesFunctionalTest.php

@@ -25,10 +25,10 @@ public function testImageStylesOnJsonApiResponse() {
     // Assert only the two configured image styles (large, thumbnail).
     $styles = $output['included'][0]['attributes']['image_style_uri'];
     $this->assertCount(2, $styles);
-    $this->assertObjectHasAttribute('large', $styles);
-    $this->assertObjectHasAttribute('thumbnail', $styles);
-    $this->assertObjectNotHasAttribute('wide', $styles);
-    $this->assertObjectNotHasAttribute('medium', $styles);
+    $this->assertArrayHasKey('large', $styles);
+    $this->assertArrayHasKey('thumbnail', $styles);
+    $this->assertArrayNotHasKey('wide', $styles);
+    $this->assertArrayNotHasKey('medium', $styles);
   }
 
 }