diff --git a/tests/Models/NullWikiApp.php b/tests/Models/NullWikiApp.php
new file mode 100644
index 0000000..a93dc6a
--- /dev/null
+++ b/tests/Models/NullWikiApp.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\Knowledgebase\tests\Models;
+
+use Modules\Knowledgebase\Models\NullWikiApp;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiApp
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Knowledgebase\Models\WikiApp', new NullWikiApp());
+    }
+
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiApp
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullWikiApp(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullWikiCategory.php b/tests/Models/NullWikiCategory.php
new file mode 100644
index 0000000..315a429
--- /dev/null
+++ b/tests/Models/NullWikiCategory.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\Knowledgebase\tests\Models;
+
+use Modules\Knowledgebase\Models\NullWikiCategory;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiCategory
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Knowledgebase\Models\WikiCategory', new NullWikiCategory());
+    }
+
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiCategory
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullWikiCategory(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullWikiCategoryTest.php b/tests/Models/NullWikiCategoryTest.php
new file mode 100644
index 0000000..93c3630
--- /dev/null
+++ b/tests/Models/NullWikiCategoryTest.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\Knowledgebase\tests\Models;
+
+use Modules\Knowledgebase\Models\NullWikiCategory;
+
+/**
+ * @internal
+ */
+final class NullWikiCategoryTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiCategory
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Knowledgebase\Models\WikiCategory', new NullWikiCategory());
+    }
+
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiCategory
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullWikiCategory(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullWikiDoc.php b/tests/Models/NullWikiDoc.php
new file mode 100644
index 0000000..4da5662
--- /dev/null
+++ b/tests/Models/NullWikiDoc.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\Knowledgebase\tests\Models;
+
+use Modules\Knowledgebase\Models\NullWikiDoc;
+
+/**
+ * @internal
+ */
+final class Null extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiDoc
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Knowledgebase\Models\WikiDoc', new NullWikiDoc());
+    }
+
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiDoc
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullWikiDoc(2);
+        self::assertEquals(2, $null->getId());
+    }
+}
diff --git a/tests/Models/NullWikiDocTest.php b/tests/Models/NullWikiDocTest.php
new file mode 100644
index 0000000..3ef96f5
--- /dev/null
+++ b/tests/Models/NullWikiDocTest.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\Knowledgebase\tests\Models;
+
+use Modules\Knowledgebase\Models\NullWikiDoc;
+
+/**
+ * @internal
+ */
+final class NullWikiDocTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiDoc
+     * @group framework
+     */
+    public function testNull() : void
+    {
+        self::assertInstanceOf('\Modules\Knowledgebase\Models\WikiDoc', new NullWikiDoc());
+    }
+
+    /**
+     * @covers Modules\Knowledgebase\Models\NullWikiDoc
+     * @group framework
+     */
+    public function testId() : void
+    {
+        $null = new NullWikiDoc(2);
+        self::assertEquals(2, $null->getId());
+    }
+}