diff --git a/tests/Models/NullAccountRelationTest.php b/tests/Models/NullAccountRelationTest.php
new file mode 100644
index 0000000..15687e8
--- /dev/null
+++ b/tests/Models/NullAccountRelationTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Jingga
+ *
+ * PHP Version 8.1
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 2.0
+ * @version   1.0.0
+ * @link      https://jingga.app
+ */
+declare(strict_types=1);
+
+namespace Modules\Tasks\tests\Models;
+
+use Modules\Tasks\Models\NullAccountRelation;
+
+/**
+ * @internal
+ */
+final class NullAccountRelationTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Tasks\Models\NullAccountRelation
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Tasks\Models\AccountRelation', new NullAccountRelation());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullAccountRelation
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullAccountRelation(2);
+        self::assertEquals(2, $null->getId());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullAccountRelation
+     * @group framework
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullAccountRelation(2);
+        self::assertEquals(['id' => 2], $null);
+    }
+}
diff --git a/tests/Models/NullGroupRelationTest.php b/tests/Models/NullGroupRelationTest.php
new file mode 100644
index 0000000..da92fdd
--- /dev/null
+++ b/tests/Models/NullGroupRelationTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Jingga
+ *
+ * PHP Version 8.1
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 2.0
+ * @version   1.0.0
+ * @link      https://jingga.app
+ */
+declare(strict_types=1);
+
+namespace Modules\Tasks\tests\Models;
+
+use Modules\Tasks\Models\NullGroupRelation;
+
+/**
+ * @internal
+ */
+final class NullGroupRelationTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Tasks\Models\NullGroupRelation
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Tasks\Models\GroupRelation', new NullGroupRelation());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullGroupRelation
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullGroupRelation(2);
+        self::assertEquals(2, $null->getId());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullGroupRelation
+     * @group framework
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullGroupRelation(2);
+        self::assertEquals(['id' => 2], $null);
+    }
+}
diff --git a/tests/Models/NullTaskAttributeTest.php b/tests/Models/NullTaskAttributeTest.php
new file mode 100644
index 0000000..38a6f65
--- /dev/null
+++ b/tests/Models/NullTaskAttributeTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Jingga
+ *
+ * PHP Version 8.1
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 2.0
+ * @version   1.0.0
+ * @link      https://jingga.app
+ */
+declare(strict_types=1);
+
+namespace Modules\Tasks\tests\Models;
+
+use Modules\Tasks\Models\NullTaskAttribute;
+
+/**
+ * @internal
+ */
+final class NullTaskAttributeTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttribute
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Tasks\Models\TaskAttribute', new NullTaskAttribute());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttribute
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullTaskAttribute(2);
+        self::assertEquals(2, $null->getId());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttribute
+     * @group framework
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullTaskAttribute(2);
+        self::assertEquals(['id' => 2], $null);
+    }
+}
diff --git a/tests/Models/NullTaskAttributeTypeTest.php b/tests/Models/NullTaskAttributeTypeTest.php
new file mode 100644
index 0000000..e533700
--- /dev/null
+++ b/tests/Models/NullTaskAttributeTypeTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Jingga
+ *
+ * PHP Version 8.1
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 2.0
+ * @version   1.0.0
+ * @link      https://jingga.app
+ */
+declare(strict_types=1);
+
+namespace Modules\Tasks\tests\Models;
+
+use Modules\Tasks\Models\NullTaskAttributeType;
+
+/**
+ * @internal
+ */
+final class NullTaskAttributeTypeTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttributeType
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Tasks\Models\TaskAttributeType', new NullTaskAttributeType());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttributeType
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullTaskAttributeType(2);
+        self::assertEquals(2, $null->getId());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttributeType
+     * @group framework
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullTaskAttributeType(2);
+        self::assertEquals(['id' => 2], $null);
+    }
+}
diff --git a/tests/Models/NullTaskAttributeValueTest.php b/tests/Models/NullTaskAttributeValueTest.php
new file mode 100644
index 0000000..422d3cc
--- /dev/null
+++ b/tests/Models/NullTaskAttributeValueTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Jingga
+ *
+ * PHP Version 8.1
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 2.0
+ * @version   1.0.0
+ * @link      https://jingga.app
+ */
+declare(strict_types=1);
+
+namespace Modules\Tasks\tests\Models;
+
+use Modules\Tasks\Models\NullTaskAttributeValue;
+
+/**
+ * @internal
+ */
+final class NullTaskAttributeValueTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttributeValue
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Tasks\Models\TaskAttributeValue', new NullTaskAttributeValue());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttributeValue
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullTaskAttributeValue(2);
+        self::assertEquals(2, $null->getId());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskAttributeValue
+     * @group framework
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullTaskAttributeValue(2);
+        self::assertEquals(['id' => 2], $null);
+    }
+}
diff --git a/tests/Models/NullTaskSeenTest.php b/tests/Models/NullTaskSeenTest.php
new file mode 100644
index 0000000..b38c9d5
--- /dev/null
+++ b/tests/Models/NullTaskSeenTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Jingga
+ *
+ * PHP Version 8.1
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 2.0
+ * @version   1.0.0
+ * @link      https://jingga.app
+ */
+declare(strict_types=1);
+
+namespace Modules\Tasks\tests\Models;
+
+use Modules\Tasks\Models\NullTaskSeen;
+
+/**
+ * @internal
+ */
+final class NullTaskSeenTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Tasks\Models\NullTaskSeen
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Tasks\Models\TaskSeen', new NullTaskSeen());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskSeen
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullTaskSeen(2);
+        self::assertEquals(2, $null->getId());
+    }
+
+    /**
+     * @covers Modules\Tasks\Models\NullTaskSeen
+     * @group framework
+     */
+    public function testJsonSerialize() : void
+    {
+        $null = new NullTaskSeen(2);
+        self::assertEquals(['id' => 2], $null);
+    }
+}