diff --git a/README.md b/README.md
index 9d30129..fad977c 100644
--- a/README.md
+++ b/README.md
@@ -1,16 +1,17 @@
 # Sample cart project
 
 ## sample usage
+
 ```
 <?php
 
-    $basket = (new BasketFactory())->createRegularBasket();
-    $basket->add('G01');
-    $basket->add('R01');
-    $basket->add('R01');
-    $basket->add('R01');
+    $simpleCart = new SimpleCartFacade();
+    $simpleCart->add('G01');
+    $simpleCart->add('R01');
+    $simpleCart->add('R01');
+    $simpleCart->add('R01');
     
-    $total = $basket->total();
+    $total = $simpleCart->total();
 ```
 
 ## assumptions:
@@ -30,15 +31,15 @@
 ## instalation
 
 1. `docker-compose up -d`
-2. inside container `composer install` 
+2. inside container `composer install`
    or simply `docker exec -it php_sample_cart bash -c "composer install"`
 
 ## run tests:
 
 - unit
-    -  `docker exec -it php_sample_cart bash -c "vendor/bin/phpunit --configuration phpunit --testsuite 'Unit Tests'"`
+    - `docker exec -it php_sample_cart bash -c "vendor/bin/phpunit --configuration phpunit.xml --testsuite 'Unit Tests'"`
 - integration
-    -  `docker exec -it php_sample_cart bash -c "vendor/bin/phpunit --configuration phpunit --testsuite 'Integration Tests'"`
+    - `docker exec -it php_sample_cart bash -c "vendor/bin/phpunit --configuration phpunit.xml --testsuite 'Integration Tests'"`
 - unit + integration:
     - `docker exec -it php_sample_cart bash -c "composer test"`
 - static tests (`phpstan`)
diff --git a/docker-compose.yml b/docker-compose.yml
index 5fb2786..1d710b8 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,5 +1,3 @@
-version: '3.8'
-
 services:
   php:
     build:
diff --git a/phpunit.xml b/phpunit.xml
index 7493d7e..bcf8a31 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,5 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         displayDetailsOnTestsThatTriggerDeprecations="true"
+         displayDetailsOnTestsThatTriggerErrors="true"
+         displayDetailsOnTestsThatTriggerNotices="true"
          displayDetailsOnTestsThatTriggerWarnings="true"
          bootstrap="vendor/autoload.php"
          colors="true"
diff --git a/src/App/CartFacade.php b/src/App/CartFacade.php
new file mode 100644
index 0000000..a8f8c67
--- /dev/null
+++ b/src/App/CartFacade.php
@@ -0,0 +1,13 @@
+<?php
+declare(strict_types=1);
+
+namespace App\App;
+
+use App\Model\BasketFactory;
+
+interface CartFacade
+{
+    public function add(string $code): void;
+
+    public function total(): float;
+}
diff --git a/src/App/SimpleCartFacade.php b/src/App/SimpleCartFacade.php
new file mode 100644
index 0000000..27d2ca5
--- /dev/null
+++ b/src/App/SimpleCartFacade.php
@@ -0,0 +1,33 @@
+<?php
+declare(strict_types=1);
+
+namespace App\App;
+
+use App\Model\Basket;
+use App\Model\BasketFactory;
+use App\Model\RegularBasketFactory;
+
+class SimpleCartFacade implements CartFacade
+{
+    private Basket $regularBasket;
+
+    public function __construct()
+    {
+        $this->regularBasket = $this->createBasketFactory()->createRegularBasket();
+    }
+
+    public function add(string $code): void
+    {
+        $this->regularBasket->add($code);
+    }
+
+    public function total(): float
+    {
+        return $this->regularBasket->total();
+    }
+
+    private function createBasketFactory(): BasketFactory
+    {
+        return new RegularBasketFactory();
+    }
+}
diff --git a/src/Model/BasketFactory.php b/src/Model/BasketFactory.php
index 26729ae..fe02b71 100644
--- a/src/Model/BasketFactory.php
+++ b/src/Model/BasketFactory.php
@@ -6,36 +6,7 @@
 use App\Repository\JsonProductRepository;
 use App\Repository\ProductRepository;
 
-class BasketFactory
+interface BasketFactory
 {
-    public function createRegularBasket(): Basket
-    {
-        return new RegularBasket(
-            $this->createProductCatalogueFilterable(),
-            $this->createShippingCostCalculator(),
-            $this->createDiscountOfferCalculator(),
-        );
-    }
-
-    private function createProductCatalogueFilterable(): ProductCatalogueFilterable
-    {
-        return new ProductCatalogue(
-            $this->createProductRepository(),
-        );
-    }
-
-    private function createProductRepository(): ProductRepository
-    {
-        return new JsonProductRepository();
-    }
-
-    private function createShippingCostCalculator(): ShippingCostCalculator
-    {
-        return new BaseShippingCostCalculator();
-    }
-
-    private function createDiscountOfferCalculator(): DiscountOfferCalculator
-    {
-        return new BaseDiscountOfferCalculator();
-    }
-}
\ No newline at end of file
+    public function createRegularBasket(): Basket;
+}
diff --git a/src/Model/RegularBasket.php b/src/Model/RegularBasket.php
index c5922a2..4b31c58 100644
--- a/src/Model/RegularBasket.php
+++ b/src/Model/RegularBasket.php
@@ -36,4 +36,4 @@ public function total(): float
 
         return round($total, 2);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Model/RegularBasketFactory.php b/src/Model/RegularBasketFactory.php
new file mode 100644
index 0000000..736c705
--- /dev/null
+++ b/src/Model/RegularBasketFactory.php
@@ -0,0 +1,41 @@
+<?php
+declare(strict_types=1);
+
+namespace App\Model;
+
+use App\Repository\JsonProductRepository;
+use App\Repository\ProductRepository;
+
+class RegularBasketFactory implements BasketFactory
+{
+    public function createRegularBasket(): Basket
+    {
+        return new RegularBasket(
+            $this->createProductCatalogueFilterable(),
+            $this->createShippingCostCalculator(),
+            $this->createDiscountOfferCalculator(),
+        );
+    }
+
+    private function createProductCatalogueFilterable(): ProductCatalogueFilterable
+    {
+        return new ProductCatalogue(
+            $this->createProductRepository(),
+        );
+    }
+
+    private function createProductRepository(): ProductRepository
+    {
+        return new JsonProductRepository();
+    }
+
+    private function createShippingCostCalculator(): ShippingCostCalculator
+    {
+        return new BaseShippingCostCalculator();
+    }
+
+    private function createDiscountOfferCalculator(): DiscountOfferCalculator
+    {
+        return new BaseDiscountOfferCalculator();
+    }
+}
diff --git a/tests/Integration/Model/RegularBasketTest.php b/tests/Integration/App/SimpleCartFacadeTest.php
similarity index 86%
rename from tests/Integration/Model/RegularBasketTest.php
rename to tests/Integration/App/SimpleCartFacadeTest.php
index eaaf89f..0646d17 100644
--- a/tests/Integration/Model/RegularBasketTest.php
+++ b/tests/Integration/App/SimpleCartFacadeTest.php
@@ -1,20 +1,21 @@
 <?php
 declare(strict_types=1);
 
-namespace App\Unit\Tests\Model;
+namespace App\Unit\Tests\Itegration\App;
 
-use App\Model\Basket;
-use App\Model\BasketFactory;
+use App\App\CartFacade;
+use App\App\SimpleCartFacade;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 
-final class RegularBasketTest extends TestCase
+class SimpleCartFacadeTest extends TestCase
 {
-    private Basket $sut;
+
+    private CartFacade $sut;
 
     protected function setUp(): void
     {
-        $this->sut = (new BasketFactory())->createRegularBasket();
+        $this->sut = new SimpleCartFacade();
 
         parent::setUp();
     }
diff --git a/tests/Unit/Model/BaseDiscountOfferCalculatorTest.php b/tests/Unit/Model/BaseDiscountOfferCalculatorTest.php
new file mode 100644
index 0000000..2ee5c78
--- /dev/null
+++ b/tests/Unit/Model/BaseDiscountOfferCalculatorTest.php
@@ -0,0 +1,57 @@
+<?php
+declare(strict_types=1);
+
+namespace App\Tests\Unit\Model;
+
+use App\Entity\Product;
+use App\Model\BaseDiscountOfferCalculator;
+use App\Model\DiscountOfferCalculator;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+class BaseDiscountOfferCalculatorTest extends TestCase
+{
+    private DiscountOfferCalculator $sut;
+
+    protected function setUp(): void
+    {
+        $this->sut = new BaseDiscountOfferCalculator();
+        parent::setUp();
+    }
+
+    /**
+     * @param array<Product> $productList
+     */
+    #[DataProvider('totalDataProvider')]
+    public function testShippingCostStrategiesProvidesCorrectValue(array $productList, float $expectedDiscount): void
+    {
+        $actualShippingCosts = $this->sut->calculate($productList);
+
+        $this->assertEquals($expectedDiscount, $actualShippingCosts);
+    }
+
+    /**
+     * @return array<string, array<string,array<Product>|float>>
+     */
+    public static function totalDataProvider(): array
+    {
+        $aRedProduct = new Product();
+        $aRedProduct->setCode('R01');
+        $aRedProduct->setName('RedOne');
+        $aRedProduct->setPrice(10.0);
+
+
+        $aGreenProduct = new Product();
+        $aGreenProduct->setCode('G01');
+        $aGreenProduct->setName('GreenOne');
+        $aGreenProduct->setPrice(100.0);
+
+        return [
+            'Two red products gives discount'        => ['productList' => [$aRedProduct, $aRedProduct], 'expectedDiscount' => 5.0],
+            'Three red products gives discount once' => ['productList' => [$aRedProduct, $aRedProduct, $aRedProduct], 'expectedDiscount' => 5.0],
+            'Four red products gives discount once'  => ['productList' => [$aRedProduct, $aRedProduct, $aRedProduct, $aRedProduct], 'expectedDiscount' => 10.0],
+            'Two green products dont gives discount' => ['productList' => [$aGreenProduct, $aGreenProduct], 'expectedDiscount' => .0],
+            'Mixed products dont gives discount'     => ['productList' => [$aRedProduct, $aGreenProduct], 'expectedDiscount' => .0],
+        ];
+    }
+}
diff --git a/tests/Unit/Model/BaseShippingCostCalculatorTest.php b/tests/Unit/Model/BaseShippingCostCalculatorTest.php
new file mode 100644
index 0000000..3170200
--- /dev/null
+++ b/tests/Unit/Model/BaseShippingCostCalculatorTest.php
@@ -0,0 +1,42 @@
+<?php
+declare(strict_types=1);
+
+namespace App\Tests\Unit\Model;
+
+use App\Model\BaseShippingCostCalculator;
+use App\Model\ShippingCostCalculator;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+class BaseShippingCostCalculatorTest extends TestCase
+{
+    private ShippingCostCalculator $sut;
+
+    protected function setUp(): void
+    {
+        $this->sut = new BaseShippingCostCalculator();
+        parent::setUp();
+    }
+
+    #[DataProvider('totalDataProvider')]
+    public function testShippingCostStrategiesProvidesCorrectValue(float $total, float $expectedShippingCost): void
+    {
+        $actualShippingCosts = $this->sut->calculate($total);
+
+        $this->assertEquals($expectedShippingCost, $actualShippingCosts);
+    }
+
+    /**
+     * @return array<string, array<string,float>>
+     */
+    public static function totalDataProvider(): array
+    {
+        return [
+            'Low shipping cost strategy is calculated'    => ['total' => 10.0, 'expectedShippingCost' => 4.95],
+            'Medium shipping cost strategy is calculated on boundary value' => ['total' => 50.0, 'expectedShippingCost' => 2.95],
+            'Medium shipping cost strategy is calculated' => ['total' => 51.0, 'expectedShippingCost' => 2.95],
+            'High shipping cost strategy is calculated on boundary value'   => ['total' => 90.0, 'expectedShippingCost' => .0],
+            'High shipping cost strategy is calculated'   => ['total' => 91.0, 'expectedShippingCost' => .0],
+        ];
+    }
+}
diff --git a/tests/Unit/Model/ProductCatalogueTest.php b/tests/Unit/Model/ProductCatalogueTest.php
index 532bb76..f4007d1 100644
--- a/tests/Unit/Model/ProductCatalogueTest.php
+++ b/tests/Unit/Model/ProductCatalogueTest.php
@@ -1,7 +1,7 @@
 <?php
 declare(strict_types=1);
 
-namespace App\Tests\Model;
+namespace App\Tests\Unit\Model;
 
 use App\Entity\Product;
 use App\Exception\ProductNotFoundException;
diff --git a/tests/Unit/Model/RegularBasketTest.php b/tests/Unit/Model/RegularBasketTest.php
new file mode 100644
index 0000000..25f5695
--- /dev/null
+++ b/tests/Unit/Model/RegularBasketTest.php
@@ -0,0 +1,93 @@
+<?php
+declare(strict_types=1);
+
+namespace App\Tests\Unit\Model;
+
+use App\Entity\Product;
+use App\Model\Basket;
+use App\Model\DiscountOfferCalculator;
+use App\Model\ProductCatalogueFilterable;
+use App\Model\RegularBasket;
+use App\Model\ShippingCostCalculator;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use ReflectionClass;
+
+class RegularBasketTest extends TestCase
+{
+    private ProductCatalogueFilterable&MockObject $productCatalogue;
+    private ShippingCostCalculator&MockObject $shippingCostCalculator;
+    private DiscountOfferCalculator&MockObject $discountCalculator;
+    private Basket $sut;
+
+    protected function setUp(): void
+    {
+        $this->productCatalogue = $this->createMock(ProductCatalogueFilterable::class);
+        $this->shippingCostCalculator = $this->createMock(ShippingCostCalculator::class);
+        $this->discountCalculator = $this->createMock(DiscountOfferCalculator::class);
+
+        $this->sut = new RegularBasket(
+            $this->productCatalogue,
+            $this->shippingCostCalculator,
+            $this->discountCalculator
+        );
+
+        parent::setUp();
+    }
+
+    #[DataProvider('calculationDataProvider')]
+    public function testTotalsCalculation(float $productPrice, float $shippingCost, float $discount, float $expectedTotal): void
+    {
+        $aProduct = new Product();
+        $aProduct->setPrice($productPrice);
+
+        $this->productCatalogue->expects($this->once())
+            ->method('getProductByCode')
+            ->willReturn($aProduct);
+        $this->discountCalculator->expects($this->once())
+            ->method('calculate')
+            ->with([$aProduct])
+            ->willReturn($discount);
+        $this->shippingCostCalculator->expects($this->once())
+            ->method('calculate')
+            ->with($productPrice - $discount)
+            ->willReturn($shippingCost);
+
+        $this->sut->add('SomeCode');
+
+        $actualTotal = $this->sut->total();
+
+        $this->assertEquals($expectedTotal, $actualTotal);
+    }
+
+    /**
+     * @return array<string,array<string,float>>
+     */
+    public static function calculationDataProvider(): array
+    {
+        return [
+            'No shipping, no discount' => ['productPrice' => 100.0, 'shippingCost' => .0, 'discount' => .0, 'expectedTotal' => 100.0],
+            'Shipping, no discount'    => ['productPrice' => 100.0, 'shippingCost' => 10.0, 'discount' => .0, 'expectedTotal' => 110.0],
+            'No shipping, Discount'    => ['productPrice' => 100.0, 'shippingCost' => .0, 'discount' => 10.0, 'expectedTotal' => 90.0],
+            'Shipping, Discount'       => ['productPrice' => 100.0, 'shippingCost' => 10.0, 'discount' => 5.0, 'expectedTotal' => 105.0],
+        ];
+    }
+
+    public function testAddToCartIsTriggeringCatalogue(): void
+    {
+        $this->productCatalogue->expects($this->exactly(3))
+            ->method('getProductByCode')
+            ->willReturn(new Product());
+
+        $this->sut->add('R01');
+        $this->sut->add('G01');
+        $this->sut->add('G01');
+
+        $sutReflection = new ReflectionClass($this->sut);
+        $property = $sutReflection->getProperty('items');
+        $actualItems = (array)$property->getValue($this->sut);
+
+        $this->assertEquals(3, count($actualItems));
+    }
+}