diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 9880de9..031cbbd 100755
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -120,7 +120,7 @@ final class ApiController extends Controller
     private function validateBillCreate(RequestAbstract $request) : array
     {
         $val = [];
-        if (($val['client/customer'] = empty($request->getData('client') && empty($request->getData('supplier'))))
+        if (($val['client/customer'] = (empty($request->getData('client')) && empty($request->getData('supplier'))))
         ) {
             return $val;
         }
@@ -274,10 +274,12 @@ final class ApiController extends Controller
 
         $status = !\is_dir($pdfDir) ? \mkdir($pdfDir, 0755, true) : true;
         if ($status === false) {
+            // @codeCoverageIgnoreStart
             $response->set($request->uri->__toString(), new FormValidation(['status' => $status]));
             $response->header->status = RequestStatusCode::R_400;
 
             return;
+            // @codeCoverageIgnoreEnd
         }
 
         $view = new View($this->app->l11nManager, $request, $response);
diff --git a/Models/Bill.php b/Models/Bill.php
index 6e74dab..ba46a0f 100755
--- a/Models/Bill.php
+++ b/Models/Bill.php
@@ -621,11 +621,35 @@ class Bill implements \JsonSerializable
         return new NullMedia();
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function toArray() : array
+    {
+        return [
+            'id' => $this->id,
+            'number' => $this->number,
+            'type' => $this->type,
+            'shipTo' => $this->shipTo,
+            'shipFAO' => $this->shipFAO,
+            'shipAddress' => $this->shipAddress,
+            'shipCity' => $this->shipCity,
+            'shipZip' => $this->shipZip,
+            'shipCountry' => $this->shipCountry,
+            'billTo' => $this->billTo,
+            'billFAO' => $this->billFAO,
+            'billAddress' => $this->billAddress,
+            'billCity' => $this->billCity,
+            'billZip' => $this->billZip,
+            'billCountry' => $this->billCountry,
+        ];
+    }
+
     /**
      * {@inheritdoc}
      */
     public function jsonSerialize()
     {
-        return [];
+        return $this->toArray();
     }
 }
diff --git a/Models/BillElement.php b/Models/BillElement.php
index ac17f62..0a8bf81 100755
--- a/Models/BillElement.php
+++ b/Models/BillElement.php
@@ -133,11 +133,28 @@ class BillElement implements \JsonSerializable
         $this->item = $item;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function toArray() : array
+    {
+        return [
+            'id' => $this->id,
+            'order' => $this->order,
+            'item' => $this->item,
+            'itemNumber' => $this->itemNumber,
+            'itemName' => $this->itemName,
+            'itemDescription' => $this->itemDescription,
+            'quantity' => $this->quantity,
+            'bill' => $this->bill,
+        ];
+    }
+
     /**
      * {@inheritdoc}
      */
     public function jsonSerialize()
     {
-        return [];
+        return $this->toArray();
     }
 }
diff --git a/Models/BillType.php b/Models/BillType.php
index c69ab39..f9cc24e 100755
--- a/Models/BillType.php
+++ b/Models/BillType.php
@@ -48,7 +48,7 @@ class BillType
     /**
      * Constructor.
      *
-     * @param string $name Name/identifier of the attribute type
+     * @param string $name Name
      *
      * @since 1.0.0
      */
diff --git a/Models/SalesBillMapper.php b/Models/SalesBillMapper.php
index 8f34bbf..a8c7b9e 100755
--- a/Models/SalesBillMapper.php
+++ b/Models/SalesBillMapper.php
@@ -232,7 +232,7 @@ final class SalesBillMapper extends BillMapper
     /**
      * Placeholder
      */
-    public static function getItemTopCustomers(int $id, \DateTime $start, \DateTime $end, int $limit = 10) : array
+    public static function getItemTopClients(int $id, \DateTime $start, \DateTime $end, int $limit = 10) : array
     {
         $depth = 3;
 
diff --git a/info.json b/info.json
index 02dd43f..93e0551 100755
--- a/info.json
+++ b/info.json
@@ -31,8 +31,9 @@
     "load": [
         {
             "pid": [
-                "/sales/billing",
-                "/purchase/billing"
+                "/sales/bill",
+                "/purchase/bill",
+                "/warehouse/bill"
             ],
             "type": 4,
             "for": 0,
diff --git a/tests/Admin/AdminTest.php b/tests/Admin/AdminTest.php
index 327a5a0..e1d97d3 100644
--- a/tests/Admin/AdminTest.php
+++ b/tests/Admin/AdminTest.php
@@ -21,7 +21,7 @@ final class AdminTest extends \PHPUnit\Framework\TestCase
 {
     protected const NAME = 'Billing';
 
-    protected const URI_LOAD = 'http://127.0.0.1/en/backend/admin/audit';
+    protected const URI_LOAD = 'http://127.0.0.1/en/backend/sales/bill';
 
     use \Modules\tests\ModuleTestTrait;
 }
diff --git a/tests/Controller/ApiControllerTest.php b/tests/Controller/ApiControllerTest.php
index b341dfc..1181374 100644
--- a/tests/Controller/ApiControllerTest.php
+++ b/tests/Controller/ApiControllerTest.php
@@ -96,7 +96,7 @@ final class ApiControllerTest extends \PHPUnit\Framework\TestCase
      * @covers Modules\Billing\Controller\ApiController
      * @group module
      */
-    public function testBillCreate() : void
+    public function testBillClientCreate() : void
     {
         $response = new HttpResponse();
         $request  = new HttpRequest(new HttpUri(''));
@@ -164,6 +164,80 @@ final class ApiControllerTest extends \PHPUnit\Framework\TestCase
         self::assertGreaterThan(0, $result === null ? -1 : $result['response']?->getId());
     }
 
+    /**
+     * Tests bill, bill element and bill pdf archive create
+     *
+     * @covers Modules\Billing\Controller\ApiController
+     * @group module
+     */
+    public function testBillSupplierCreate() : void
+    {
+        $response = new HttpResponse();
+        $request  = new HttpRequest(new HttpUri(''));
+
+        $request->header->account = 1;
+
+        $request->setData('supplier', 1);
+        $request->setData('address', null);
+        $request->setData('type', 1);
+        $request->setData('status', null); // null = system settings, value = individual input
+        $request->setData('performancedate', DateTime::generateDateTime(new \DateTime('2015-01-01'), new \DateTime('now'))->format('Y-m-d H:i:s'));
+        $request->setData('sales_referral', null); // who these sales belong to
+        $request->setData('shipping_terms', 1); // e.g. incoterms
+        $request->setData('shipping_type', 1);
+        $request->setData('shipping_cost', null);
+        $request->setData('insurance_type', 1);
+        $request->setData('insurance_cost', null); // null = system settings, value = individual input
+        $request->setData('info', null); // null = system settings, value = individual input
+        $request->setData('currency', null); // null = system settings, value = individual input
+        $request->setData('payment', null); // null = system settings, value = individual input
+        $request->setData('payment_terms', null); // null = system settings, value = individual input
+
+        $this->module->apiBillCreate($request, $response);
+
+        $bId = $response->get('')['response']->getId();
+        self::assertGreaterThan(0, $bId);
+
+        for ($k = 0; $k < 10; ++$k) {
+            $response = new HttpResponse();
+            $request  = new HttpRequest(new HttpUri(''));
+
+            $request->header->account = 1;
+
+            $iId = \mt_rand(0, 10);
+
+            $request->setData('bill', $bId);
+            $request->setData('item', $iId === 0 ? null : $iId);
+
+            if ($iId === 0) {
+                // @todo: add text
+            }
+
+            $request->setData('quantity', \mt_rand(1, 11));
+            $request->setData('tax', null);
+            $request->setData('text', $iId === 0 ? 'Some test text' : null);
+
+            // discounts
+            if (\mt_rand(1, 100) < 31) {
+                $request->setData('discount_percentage', \mt_rand(5, 30));
+            }
+
+            $this->module->apiBillElementCreate($request, $response);
+            self::assertGreaterThan(0, $response->get('')['response']->getId());
+        }
+
+        $response = new HttpResponse();
+        $request  = new HttpRequest(new HttpUri(''));
+
+        $request->header->account = 1;
+        $request->setData('bill', $bId);
+
+        $this->module->apiBillPdfArchiveCreate($request, $response);
+
+        $result = $response->get('');
+        self::assertGreaterThan(0, $result === null ? -1 : $result['response']?->getId());
+    }
+
     /**
      * @covers Modules\Billing\Controller\ApiController
      * @group module
@@ -174,8 +248,25 @@ final class ApiControllerTest extends \PHPUnit\Framework\TestCase
         $request  = new HttpRequest(new HttpUri(''));
 
         $request->header->account = 1;
+        $request->setData('invalid', '1');
 
         $this->module->apiBillCreate($request, $response);
         self::assertEquals(RequestStatusCode::R_400, $response->header->status);
     }
+
+    /**
+     * @covers Modules\Billing\Controller\ApiController
+     * @group module
+     */
+    public function testBillElementCreateInvalidData() : void
+    {
+        $response = new HttpResponse();
+        $request  = new HttpRequest(new HttpUri(''));
+
+        $request->header->account = 1;
+        $request->setData('invalid', '1');
+
+        $this->module->apiBillElementCreate($request, $response);
+        self::assertEquals(RequestStatusCode::R_400, $response->header->status);
+    }
 }
diff --git a/tests/Models/BillElementTest.php b/tests/Models/BillElementTest.php
index 1b1dd9a..9520ccf 100644
--- a/tests/Models/BillElementTest.php
+++ b/tests/Models/BillElementTest.php
@@ -45,9 +45,42 @@ final class BillElementTest extends \PHPUnit\Framework\TestCase
         self::assertInstanceOf('\phpOMS\Localization\Money', $this->element->totalPurchasePriceNet);
     }
 
+    /**
+     * @covers Modules\Billing\Models\BillElement
+     * @group module
+     */
     public function testItemInputOutput() : void
     {
         $this->element->setItem(123);
         self::assertEquals(123, $this->element->item);
     }
+
+    /**
+     * @covers Modules\Billing\Models\BillElement
+     * @group module
+     */
+    public function testSerialize() : void
+    {
+        $this->element->order = 2;
+        $this->element->item = 3;
+        $this->element->itemNumber = '123456';
+        $this->element->itemName = 'Test';
+        $this->element->itemDescription = 'Description';
+        $this->element->quantity = 4;
+        $this->element->bill = 5;
+
+        self::assertEquals(
+            [
+                'id'       => 0,
+                'order' => 2,
+                'item' => 3,
+                'itemNumber' => '123456',
+                'itemName' => 'Test',
+                'itemDescription' => 'Description',
+                'quantity' => 4,
+                'bill' => 5,
+            ],
+            $this->element->jsonSerialize()
+        );
+    }
 }
diff --git a/tests/Models/BillTest.php b/tests/Models/BillTest.php
index f2d75f2..b1c1bbd 100644
--- a/tests/Models/BillTest.php
+++ b/tests/Models/BillTest.php
@@ -15,6 +15,7 @@ declare(strict_types=1);
 namespace Modules\Billing\tests\Models;
 
 use Modules\Billing\Models\Bill;
+use Modules\Billing\Models\BillElement;
 use Modules\Billing\Models\BillStatus;
 use Modules\Billing\Models\BillType;
 use phpOMS\Localization\ISO4217CharEnum;
@@ -139,4 +140,57 @@ final class BillTest extends \PHPUnit\Framework\TestCase
         $this->bill->addTracking('TEST');
         self::assertEquals(['TEST'], $this->bill->getTrackings());
     }
+
+    /**
+     * @covers Modules\Billing\Models\Bill
+     * @group module
+     */
+    public function testElementInputOutput() : void
+    {
+        $this->bill->addElement(new BillElement());
+        self::assertCount(1, $this->bill->getElements());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\Bill
+     * @group module
+     */
+    public function testSerialize() : void
+    {
+        $this->bill->number = '123456';
+        $this->bill->type = 2;
+        $this->bill->shipTo = 'To';
+        $this->bill->shipFAO = 'FAO';
+        $this->bill->shipAddress = 'Address';
+        $this->bill->shipCity = 'City';
+        $this->bill->shipZip = 'Zip';
+        $this->bill->shipCountry = 'Country';
+        $this->bill->billTo = 'To';
+        $this->bill->billFAO = 'FAO';
+        $this->bill->billAddress = 'Address';
+        $this->bill->billCity = 'City';
+        $this->bill->billZip = 'Zip';
+        $this->bill->billCountry = 'Country';
+
+        self::assertEquals(
+            [
+                'id' => 0,
+                'number' => '123456',
+                'type' => 2,
+                'shipTo' => 'To',
+                'shipFAO' => 'FAO',
+                'shipAddress' => 'Address',
+                'shipCity' => 'City',
+                'shipZip' => 'Zip',
+                'shipCountry' => 'Country',
+                'billTo' => 'To',
+                'billFAO' => 'FAO',
+                'billAddress' => 'Address',
+                'billCity' => 'City',
+                'billZip' => 'Zip',
+                'billCountry' => 'Country',
+            ],
+            $this->bill->jsonSerialize()
+        );
+    }
 }
diff --git a/tests/Models/NullBill.php b/tests/Models/NullBill.php
deleted file mode 100644
index 6697334..0000000
--- a/tests/Models/NullBill.php
+++ /dev/null
@@ -1,42 +0,0 @@
-<?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\Billing\tests\Models;
-
-use Modules\Billing\Models\NullBill;
-
-/**
- * @internal
- */
-final class Null extends \PHPUnit\Framework\TestCase
-{
-    /**
-     * @covers Modules\Billing\Models\NullBill
-     * @group framework
-     */
-    public function testNull() : void
-    {
-        self::assertInstanceOf('\Modules\Billing\Models\Bill', new NullBill());
-    }
-
-    /**
-     * @covers Modules\Billing\Models\NullBill
-     * @group framework
-     */
-    public function testId() : void
-    {
-        $null = new NullBill(2);
-        self::assertEquals(2, $null->getId());
-    }
-}
diff --git a/tests/Models/NullBillElement.php b/tests/Models/NullBillElement.php
deleted file mode 100644
index ecf1267..0000000
--- a/tests/Models/NullBillElement.php
+++ /dev/null
@@ -1,42 +0,0 @@
-<?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\Billing\tests\Models;
-
-use Modules\Billing\Models\NullBillElement;
-
-/**
- * @internal
- */
-final class Null extends \PHPUnit\Framework\TestCase
-{
-    /**
-     * @covers Modules\Billing\Models\NullBillElement
-     * @group framework
-     */
-    public function testNull() : void
-    {
-        self::assertInstanceOf('\Modules\Billing\Models\BillElement', new NullBillElement());
-    }
-
-    /**
-     * @covers Modules\Billing\Models\NullBillElement
-     * @group framework
-     */
-    public function testId() : void
-    {
-        $null = new NullBillElement(2);
-        self::assertEquals(2, $null->getId());
-    }
-}
diff --git a/tests/Models/NullBillType.php b/tests/Models/NullBillType.php
deleted file mode 100644
index cd30551..0000000
--- a/tests/Models/NullBillType.php
+++ /dev/null
@@ -1,42 +0,0 @@
-<?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\Billing\tests\Models;
-
-use Modules\Billing\Models\NullBillType;
-
-/**
- * @internal
- */
-final class Null extends \PHPUnit\Framework\TestCase
-{
-    /**
-     * @covers Modules\Billing\Models\NullBillType
-     * @group framework
-     */
-    public function testNull() : void
-    {
-        self::assertInstanceOf('\Modules\Billing\Models\BillType', new NullBillType());
-    }
-
-    /**
-     * @covers Modules\Billing\Models\NullBillType
-     * @group framework
-     */
-    public function testId() : void
-    {
-        $null = new NullBillType(2);
-        self::assertEquals(2, $null->getId());
-    }
-}
diff --git a/tests/Models/PurchaseBillMapperTest.php b/tests/Models/PurchaseBillMapperTest.php
new file mode 100644
index 0000000..c55f219
--- /dev/null
+++ b/tests/Models/PurchaseBillMapperTest.php
@@ -0,0 +1,152 @@
+<?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\Billing\tests\Models;
+
+use Modules\Billing\Models\PurchaseBillMapper;
+use phpOMS\Utils\TestUtils;
+
+/**
+ * @testdox Modules\Billing\tests\Models\PurchaseBillMapperTest: App database mapper
+ *
+ * @internal
+ */
+final class PurchaseBillMapperTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetPurchaseBeforePivotInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getPurchaseBeforePivot(-1));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetPurchaseAfterPivotInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getPurchaseAfterPivot(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetPurchaseByItemIdInvalid() : void
+    {
+        self::assertEquals(0, PurchaseBillMapper::getPurchaseByItemId(99999, new \DateTime('now'), new \DateTime('now'))->getInt());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetPurchaseBySupplierIdInvalid() : void
+    {
+        self::assertEquals(0, PurchaseBillMapper::getPurchaseBySupplierId(99999, new \DateTime('now'), new \DateTime('now'))->getInt());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetAvgPurchasePriceByItemIdInvalid() : void
+    {
+        self::assertEquals(0, PurchaseBillMapper::getAvgPurchasePriceByItemId(99999, new \DateTime('now'), new \DateTime('now'))->getInt());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetLastOrderDateByItemIdInvalid() : void
+    {
+        self::assertEquals(null, PurchaseBillMapper::getLastOrderDateByItemId(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetLastOrderDateBySupplierIdInvalid() : void
+    {
+        self::assertEquals(null, PurchaseBillMapper::getLastOrderDateBySupplierId(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetNewestItemInvoicesInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getNewestItemInvoices(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetNewestSupplierInvoicesInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getNewestSupplierInvoices(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetItemTopSuppliersInvalid() : void
+    {
+        self::assertEquals([[], []], PurchaseBillMapper::getItemTopSuppliers(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetItemRegionPurchaseInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getItemRegionPurchase(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetItemCountryPurchaseInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getItemCountryPurchase(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetItemMonthlyPurchaseCostsInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getItemMonthlyPurchaseCosts(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\PurchaseBillMapper
+     * @group module
+     */
+    public function testGetSupplierMonthlyPurchaseCostsInvalid() : void
+    {
+        self::assertEquals([], PurchaseBillMapper::getSupplierMonthlyPurchaseCosts(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+}
diff --git a/tests/Models/SalesBillMapperTest.php b/tests/Models/SalesBillMapperTest.php
new file mode 100644
index 0000000..5eec0af
--- /dev/null
+++ b/tests/Models/SalesBillMapperTest.php
@@ -0,0 +1,170 @@
+<?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\Billing\tests\Models;
+
+use Modules\Billing\Models\SalesBillMapper;
+use phpOMS\Utils\TestUtils;
+
+/**
+ * @testdox Modules\Billing\tests\Models\SalesBillMapperTest: App database mapper
+ *
+ * @internal
+ */
+final class SalesBillMapperTest extends \PHPUnit\Framework\TestCase
+{
+	/**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetSalesBeforePivotInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getSalesBeforePivot(-1));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetSalesAfterPivotInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getSalesAfterPivot(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetSalesByItemIdInvalid() : void
+    {
+        self::assertEquals(0, SalesBillMapper::getSalesByItemId(99999, new \DateTime('now'), new \DateTime('now'))->getInt());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetSalesByClientIdInvalid() : void
+    {
+        self::assertEquals(0, SalesBillMapper::getSalesByClientId(99999, new \DateTime('now'), new \DateTime('now'))->getInt());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetAvgSalesPriceByItemIdInvalid() : void
+    {
+        self::assertEquals(0, SalesBillMapper::getAvgSalesPriceByItemId(99999, new \DateTime('now'), new \DateTime('now'))->getInt());
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetLastOrderDateByItemIdInvalid() : void
+    {
+        self::assertEquals(null, SalesBillMapper::getLastOrderDateByItemId(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetLastOrderDateByClientIdInvalid() : void
+    {
+        self::assertEquals(null, SalesBillMapper::getLastOrderDateByClientId(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetNewestItemInvoicesInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getNewestItemInvoices(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetNewestClientInvoicesInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getNewestClientInvoices(99999));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetItemTopClientsInvalid() : void
+    {
+        self::assertEquals([[], []], SalesBillMapper::getItemTopClients(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetItemBillsInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getItemBills(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetClientItem() : void
+    {
+        self::assertEquals([], SalesBillMapper::getClientItem(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetItemRegionSalesInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getItemRegionSales(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetItemCountrySalesInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getItemCountrySales(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetItemMonthlySalesCostsInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getItemMonthlySalesCosts(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\SalesBillMapper
+     * @group module
+     */
+    public function testGetClientMonthlySalesCostsInvalid() : void
+    {
+        self::assertEquals([], SalesBillMapper::getClientMonthlySalesCosts(99999, new \DateTime('now'), new \DateTime('now')));
+    }
+}
diff --git a/tests/Models/StockBillMapperTest.php b/tests/Models/StockBillMapperTest.php
new file mode 100644
index 0000000..aacf9b4
--- /dev/null
+++ b/tests/Models/StockBillMapperTest.php
@@ -0,0 +1,44 @@
+<?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\Billing\tests\Models;
+
+use Modules\Billing\Models\StockBillMapper;
+use phpOMS\Utils\TestUtils;
+
+/**
+ * @testdox Modules\Billing\tests\Models\StockBillMapperTest: App database mapper
+ *
+ * @internal
+ */
+final class StockBillMapperTest extends \PHPUnit\Framework\TestCase
+{
+	/**
+     * @covers Modules\Billing\Models\StockBillMapper
+     * @group module
+     */
+    public function testGetStockBeforePivotInvalid() : void
+    {
+        self::assertEquals([], StockBillMapper::getStockBeforePivot(-1));
+    }
+
+    /**
+     * @covers Modules\Billing\Models\StockBillMapper
+     * @group module
+     */
+    public function testGetStockAfterPivotInvalid() : void
+    {
+        self::assertEquals([], StockBillMapper::getStockAfterPivot(99999));
+    }
+}