diff --git a/tests/Models/NullEmployee.php b/tests/Models/NullEmployee.php
new file mode 100644
index 0000000..01ddad3
--- /dev/null
+++ b/tests/Models/NullEmployee.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 8.0
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace Modules\HumanResourceManagement\tests\Models;
+
+use Modules\HumanResourceManagement\Models\NullEmployee;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployee
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\HumanResourceManagement\Models\Employee', new NullEmployee());
+    }
+
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployee
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullEmployee(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullEmployeeEducationHistory.php b/tests/Models/NullEmployeeEducationHistory.php
new file mode 100644
index 0000000..c82cd38
--- /dev/null
+++ b/tests/Models/NullEmployeeEducationHistory.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 8.0
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace Modules\HumanResourceManagement\tests\Models;
+
+use Modules\HumanResourceManagement\Models\NullEmployeeEducationHistory;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployeeEducationHistory
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\HumanResourceManagement\Models\EmployeeEducationHistory', new NullEmployeeEducationHistory());
+    }
+
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployeeEducationHistory
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullEmployeeEducationHistory(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullEmployeeHistory.php b/tests/Models/NullEmployeeHistory.php
new file mode 100644
index 0000000..fab7c08
--- /dev/null
+++ b/tests/Models/NullEmployeeHistory.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 8.0
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace Modules\HumanResourceManagement\tests\Models;
+
+use Modules\HumanResourceManagement\Models\NullEmployeeHistory;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployeeHistory
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\HumanResourceManagement\Models\EmployeeHistory', new NullEmployeeHistory());
+    }
+
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployeeHistory
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullEmployeeHistory(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullEmployeeWorkHistory.php b/tests/Models/NullEmployeeWorkHistory.php
new file mode 100644
index 0000000..151d0c2
--- /dev/null
+++ b/tests/Models/NullEmployeeWorkHistory.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 8.0
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace Modules\HumanResourceManagement\tests\Models;
+
+use Modules\HumanResourceManagement\Models\NullEmployeeWorkHistory;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployeeWorkHistory
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\HumanResourceManagement\Models\EmployeeWorkHistory', new NullEmployeeWorkHistory());
+    }
+
+    /**
+     * @covers Modules\HumanResourceManagement\Models\NullEmployeeWorkHistory
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullEmployeeWorkHistory(2);
+        self::assertEquals(2, $null->getId());
+    }
+}