diff --git a/tests/Models/NullQAAnswerTest.php b/tests/Models/NullQAAnswerTest.php
index 140b4ce..f40661a 100755
--- a/tests/Models/NullQAAnswerTest.php
+++ b/tests/Models/NullQAAnswerTest.php
@@ -39,4 +39,14 @@ final class NullQAAnswerTest extends \PHPUnit\Framework\TestCase
         $null = new NullQAAnswer(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\QA\Models\NullQAAnswer
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullQAAnswer(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }
diff --git a/tests/Models/NullQAAnswerVoteTest.php b/tests/Models/NullQAAnswerVoteTest.php
index f6227a5..35e1923 100755
--- a/tests/Models/NullQAAnswerVoteTest.php
+++ b/tests/Models/NullQAAnswerVoteTest.php
@@ -39,4 +39,14 @@ final class NullQAAnswerVoteTest extends \PHPUnit\Framework\TestCase
         $null = new NullQAAnswerVote(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\QA\Models\NullQAAnswerVote
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullQAAnswerVote(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }
diff --git a/tests/Models/NullQAAppTest.php b/tests/Models/NullQAAppTest.php
index a194f63..33febf2 100755
--- a/tests/Models/NullQAAppTest.php
+++ b/tests/Models/NullQAAppTest.php
@@ -39,4 +39,14 @@ final class NullQAAppTest extends \PHPUnit\Framework\TestCase
         $null = new NullQAApp(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\QA\Models\NullQAApp
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullQAApp(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }
diff --git a/tests/Models/NullQAQuestionTest.php b/tests/Models/NullQAQuestionTest.php
index 97f677c..b70234f 100755
--- a/tests/Models/NullQAQuestionTest.php
+++ b/tests/Models/NullQAQuestionTest.php
@@ -39,4 +39,14 @@ final class NullQAQuestionTest extends \PHPUnit\Framework\TestCase
         $null = new NullQAQuestion(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\QA\Models\NullQAQuestion
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullQAQuestion(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }
diff --git a/tests/Models/NullQAQuestionVoteTest.php b/tests/Models/NullQAQuestionVoteTest.php
index c6e4d5b..f4559e9 100755
--- a/tests/Models/NullQAQuestionVoteTest.php
+++ b/tests/Models/NullQAQuestionVoteTest.php
@@ -39,4 +39,14 @@ final class NullQAQuestionVoteTest extends \PHPUnit\Framework\TestCase
         $null = new NullQAQuestionVote(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\QA\Models\NullQAQuestionVote
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullQAQuestionVote(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }