diff --git a/tests/src/Functional/JsonExtrasApiFunctionalTest.php b/tests/src/Functional/JsonExtrasApiFunctionalTest.php
index f69b6c820f606fb662144f366a26340604766d9f..2f353d001e6e9e495d26f306ab8818ff222cbfa1 100644
--- a/tests/src/Functional/JsonExtrasApiFunctionalTest.php
+++ b/tests/src/Functional/JsonExtrasApiFunctionalTest.php
@@ -106,6 +106,20 @@ class JsonExtrasApiFunctionalTest extends JsonApiFunctionalTestBase {
     // 8. Test the field enhancers: SingleNestedEnhancer.
     $output = Json::decode($this->drupalGet('/api/articles/' . $this->nodes[3]->uuid()));
     $this->assertInternalType('string', $output['data']['attributes']['body']);
+
+    // 9. Test the related endpoint.
+    // This tests the overridden resource name, the overridden field names and
+    // the disabled fields.
+    $output = Json::decode($this->drupalGet('/api/articles/' . $this->nodes[4]->uuid() . '/contentType'));
+    $this->assertArrayNotHasKey('type', $output['data']['attributes']);
+    $this->assertSame('article', $output['data']['attributes']['machineName']);
+    $this->assertSame('contentTypes', $output['data']['type']);
+    $this->assertArrayNotHasKey('uuid', $output['data']['attributes']);
+
+    // 10. Test the relationships endpoint.
+    $output = Json::decode($this->drupalGet('/api/articles/' . $this->nodes[4]->uuid() . '/relationships/contentType'));
+    $this->assertSame('contentTypes', $output['data']['type']);
+    $this->assertArrayHasKey('id', $output['data']);
   }
 
   /**