diff --git a/tests/CartTest.php b/tests/CartTest.php
new file mode 100644
index 0000000..fd4a8e1
--- /dev/null
+++ b/tests/CartTest.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Bazaar\Tests;
+
+use Bazaar\Core\Session;
+use Bazaar\Repositories\ProductRepository;
+use Bazaar\Services\Cart;
+
+final class CartTest extends DatabaseTestCase
+{
+    private function cart(): Cart
+    {
+        return new Cart(new Session(), new ProductRepository($this->db));
+    }
+
+    public function testAddAccumulatesQuantity(): void
+    {
+        $productId = $this->seedProduct('Cold Brew', 1400, 50);
+        $cart = $this->cart();
+
+        $cart->add($productId, 2);
+        $cart->add($productId, 3);
+
+        $this->assertSame(5, $cart->count());
+        $this->assertSame(1400 * 5, $cart->totalCents());
+    }
+
+    public function testAddClampsToAvailableStock(): void
+    {
+        $productId = $this->seedProduct('Sencha Tin', 1600, 3);
+        $cart = $this->cart();
+
+        $cart->add($productId, 10);
+
+        $lines = $cart->lines();
+        $this->assertCount(1, $lines);
+        $this->assertSame(3, $lines[0]['quantity']);
+    }
+
+    public function testUpdateToZeroRemovesLine(): void
+    {
+        $productId = $this->seedProduct('Notebook', 1200, 20);
+        $cart = $this->cart();
+        $cart->add($productId, 4);
+
+        $cart->update($productId, 0);
+
+        $this->assertTrue($cart->isEmpty());
+        $this->assertSame(0, $cart->totalCents());
+    }
+
+    public function testRemoveDropsProduct(): void
+    {
+        $first = $this->seedProduct('Chef Knife', 8900, 5);
+        $second = $this->seedProduct('Linen Apron', 3200, 5);
+        $cart = $this->cart();
+        $cart->add($first, 1);
+        $cart->add($second, 2);
+
+        $cart->remove($first);
+
+        $lines = $cart->lines();
+        $this->assertCount(1, $lines);
+        $this->assertSame($second, (int) $lines[0]['product']['id']);
+        $this->assertSame(3200 * 2, $cart->totalCents());
+    }
+
+    public function testUnknownProductIsIgnored(): void
+    {
+        $cart = $this->cart();
+
+        $cart->add(9999, 1);
+
+        $this->assertTrue($cart->isEmpty());
+    }
+
+    public function testLineTotalsAreComputed(): void
+    {
+        $a = $this->seedProduct('Walnut Board', 4800, 10);
+        $b = $this->seedProduct('Wool Throw', 7200, 10);
+        $cart = $this->cart();
+        $cart->add($a, 2);
+        $cart->add($b, 1);
+
+        $this->assertSame(4800 * 2 + 7200, $cart->totalCents());
+    }
+}
diff --git a/tests/WishlistTest.php b/tests/WishlistTest.php
new file mode 100644
index 0000000..7c15ad3
--- /dev/null
+++ b/tests/WishlistTest.php
@@ -0,0 +1,65 @@
+<?php
+
+namespace Bazaar\Tests;
+
+use Bazaar\Repositories\UserRepository;
+use Bazaar\Repositories\WishlistRepository;
+
+final class WishlistTest extends DatabaseTestCase
+{
+    private WishlistRepository $wishlist;
+    private int $userId;
+    private int $otherUserId;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->wishlist = new WishlistRepository($this->db);
+        $users = new UserRepository($this->db);
+        $this->userId = $users->create('a@bazaar.test', 'hash', 'A');
+        $this->otherUserId = $users->create('b@bazaar.test', 'hash', 'B');
+    }
+
+    public function testToggleAddsThenRemoves(): void
+    {
+        $productId = $this->seedProduct('Mug', 1200, 5);
+
+        $this->assertTrue($this->wishlist->toggle($this->userId, $productId));
+        $this->assertTrue($this->wishlist->has($this->userId, $productId));
+
+        $this->assertFalse($this->wishlist->toggle($this->userId, $productId));
+        $this->assertFalse($this->wishlist->has($this->userId, $productId));
+    }
+
+    public function testAddIsIdempotent(): void
+    {
+        $productId = $this->seedProduct('Mug', 1200, 5);
+
+        $this->wishlist->add($this->userId, $productId);
+        $this->wishlist->add($this->userId, $productId);
+
+        $this->assertSame(1, $this->wishlist->count($this->userId));
+    }
+
+    public function testWishlistIsScopedPerUser(): void
+    {
+        $productId = $this->seedProduct('Mug', 1200, 5);
+        $this->wishlist->add($this->userId, $productId);
+
+        $this->assertTrue($this->wishlist->has($this->userId, $productId));
+        $this->assertFalse($this->wishlist->has($this->otherUserId, $productId));
+        $this->assertSame(0, $this->wishlist->count($this->otherUserId));
+    }
+
+    public function testForUserReturnsProductRows(): void
+    {
+        $first = $this->seedProduct('Mug', 1200, 5);
+        $second = $this->seedProduct('Plate', 1800, 5);
+        $this->wishlist->add($this->userId, $first);
+        $this->wishlist->add($this->userId, $second);
+
+        $rows = $this->wishlist->forUser($this->userId);
+        $this->assertCount(2, $rows);
+        $this->assertSame([$first, $second], array_values(array_reverse(array_map('intval', array_column($rows, 'id')))));
+    }
+}