diff --git a/tests/Models/NullCommentListTest.php b/tests/Models/NullCommentListTest.php
index 975285c..6181dd2 100755
--- a/tests/Models/NullCommentListTest.php
+++ b/tests/Models/NullCommentListTest.php
@@ -23,7 +23,7 @@ final class NullCommentListTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * @covers Modules\Comments\Models\NullCommentList
-     * @group framework
+     * @group module
      */
     public function testNull() : void
     {
@@ -32,11 +32,21 @@ final class NullCommentListTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @covers Modules\Comments\Models\NullCommentList
-     * @group framework
+     * @group module
      */
     public function testId() : void
     {
         $null = new NullCommentList(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\Comments\Models\NullCommentList
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullCommentList(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }
diff --git a/tests/Models/NullCommentTest.php b/tests/Models/NullCommentTest.php
index 49bf9a2..eb038d4 100755
--- a/tests/Models/NullCommentTest.php
+++ b/tests/Models/NullCommentTest.php
@@ -23,7 +23,7 @@ final class NullCommentTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * @covers Modules\Comments\Models\NullComment
-     * @group framework
+     * @group module
      */
     public function testNull() : void
     {
@@ -32,11 +32,21 @@ final class NullCommentTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @covers Modules\Comments\Models\NullComment
-     * @group framework
+     * @group module
      */
     public function testId() : void
     {
         $null = new NullComment(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\Comments\Models\NullComment
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullComment(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }
diff --git a/tests/Models/NullCommentVoteTest.php b/tests/Models/NullCommentVoteTest.php
index ebe0e93..83b34f5 100755
--- a/tests/Models/NullCommentVoteTest.php
+++ b/tests/Models/NullCommentVoteTest.php
@@ -23,7 +23,7 @@ final class NullCommentVoteTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * @covers Modules\Comments\Models\NullCommentVote
-     * @group framework
+     * @group module
      */
     public function testNull() : void
     {
@@ -32,11 +32,21 @@ final class NullCommentVoteTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @covers Modules\Comments\Models\NullCommentVote
-     * @group framework
+     * @group module
      */
     public function testId() : void
     {
         $null = new NullCommentVote(2);
         self::assertEquals(2, $null->id);
     }
+
+    /**
+     * @covers Modules\Comments\Models\NullCommentVote
+     * @group module
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullCommentVote(2);
+        self::assertEquals(['id' => 2], $null);
+    }
 }