diff --git a/tests/VariantTest.php b/tests/VariantTest.php
new file mode 100644
index 0000000..653e9ee
--- /dev/null
+++ b/tests/VariantTest.php
@@ -0,0 +1,107 @@
+<?php
+
+namespace Bazaar\Tests;
+
+use Bazaar\Core\Session;
+use Bazaar\Repositories\AttributeRepository;
+use Bazaar\Repositories\OrderRepository;
+use Bazaar\Repositories\ProductRepository;
+use Bazaar\Repositories\UserRepository;
+use Bazaar\Repositories\VariantRepository;
+use Bazaar\Services\Cart;
+use Bazaar\Services\OrderService;
+
+final class VariantTest extends DatabaseTestCase
+{
+    private VariantRepository $variants;
+    private AttributeRepository $attributes;
+    private ProductRepository $products;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->variants = new VariantRepository($this->db);
+        $this->attributes = new AttributeRepository($this->db);
+        $this->products = new ProductRepository($this->db);
+    }
+
+    private function makeVariant(int $productId, string $sku, int $priceCents, int $stock, string $sizeValue): int
+    {
+        $attributeId = $this->attributes->findBySlug('size')
+            ? (int) $this->attributes->findBySlug('size')['id']
+            : $this->attributes->create('Size', 'size');
+        $valueRow = $this->attributes->findValueBySlug($attributeId, slugify($sizeValue));
+        $valueId = $valueRow ? (int) $valueRow['id'] : $this->attributes->createValue($attributeId, $sizeValue, slugify($sizeValue));
+
+        $variantId = $this->variants->create($productId, $sku, $priceCents, $stock);
+        $this->variants->setOption($variantId, $attributeId, $valueId);
+        return $variantId;
+    }
+
+    public function testVariantCarriesOwnPriceStockAndLabel(): void
+    {
+        $productId = $this->seedProduct('Tee', 2000, 0);
+        $variantId = $this->makeVariant($productId, 'TEE-S', 2500, 7, 'Small');
+
+        $variant = $this->variants->find($variantId);
+        $this->assertSame(2500, (int) $variant['priceCents']);
+        $this->assertSame(7, (int) $variant['stockQuantity']);
+
+        $forProduct = $this->variants->forProduct($productId);
+        $this->assertCount(1, $forProduct);
+        $this->assertSame('Small', $forProduct[0]['label']);
+    }
+
+    public function testCartUsesVariantPriceStockNotProduct(): void
+    {
+        $productId = $this->seedProduct('Tee', 2000, 100);
+        $variantId = $this->makeVariant($productId, 'TEE-M', 2500, 3, 'Medium');
+
+        $cart = new Cart(new Session(), $this->products, $this->variants);
+        $cart->add($productId, 10, $variantId);
+
+        $lines = $cart->lines();
+        $this->assertCount(1, $lines);
+        $this->assertSame(3, $lines[0]['quantity'], 'clamped to variant stock, not product stock');
+        $this->assertSame(2500, $lines[0]['unitPriceCents']);
+        $this->assertSame('Medium', $lines[0]['variantLabel']);
+        $this->assertSame(2500 * 3, $cart->totalCents());
+    }
+
+    public function testProductAndVariantLinesAreSeparate(): void
+    {
+        $productId = $this->seedProduct('Tee', 2000, 50);
+        $variantId = $this->makeVariant($productId, 'TEE-L', 2500, 20, 'Large');
+
+        $cart = new Cart(new Session(), $this->products, $this->variants);
+        $cart->add($productId, 2);
+        $cart->add($productId, 1, $variantId);
+
+        $this->assertCount(2, $cart->lines());
+        $this->assertSame(3, $cart->count());
+    }
+
+    public function testOrderDecrementsVariantStockNotProductStock(): void
+    {
+        $productId = $this->seedProduct('Tee', 2000, 50);
+        $variantId = $this->makeVariant($productId, 'TEE-XL', 2500, 8, 'Extra Large');
+        $userId = (new UserRepository($this->db))->create('v@bazaar.test', password_hash('correcthorse', PASSWORD_DEFAULT), 'V');
+
+        $cart = new Cart(new Session(), $this->products, $this->variants);
+        $cart->add($productId, 2, $variantId);
+
+        $orders = new OrderRepository($this->db);
+        $service = new OrderService($this->db, $orders, $this->products, $this->variants);
+        $orderId = $service->createFromCart($userId, $cart, 'usd');
+
+        $items = $orders->items($orderId);
+        $this->assertSame($variantId, (int) $items[0]['variantId']);
+        $this->assertSame('Extra Large', $items[0]['variantLabel']);
+        $this->assertSame(2500, (int) $items[0]['unitPriceCents']);
+
+        $service->markPaid($orderId);
+
+        $this->assertSame(6, (int) $this->variants->find($variantId)['stockQuantity']);
+        $this->assertSame(50, (int) $this->products->find($productId)['stockQuantity'], 'product stock untouched');
+    }
+}