feat: Implement inventory policy for product variants

- Introduced InventoryPolicy enum to manage tracked and unlimited inventory types.
- Updated ProductVariant model to include inventory_policy and cantidad_vendida attributes.
- Modified addItem and updateItem methods in Cart to check available quantity based on inventory policy.
- Added migration to include inventory_policy and cantidad_vendida in productos_variantes table.
- Enhanced tests to validate inventory behavior for both tracked and unlimited policies.
- Updated various request and resource classes to handle new inventory fields.

tests/Feature/Cart/CartControllerTest.php

@@ -2,14 +2,19 @@
 
 namespace Tests\Feature\Cart;
 
+use App\Domains\Attachable\Enums\AttachmentType;
+use App\Domains\Attachable\Models\Attachment;
 use App\Domains\Auth\Models\User;
-use App\Domains\Catalog\Models\Product;
+use App\Domains\Catalog\Enums\InventoryPolicy;
 use App\Domains\Catalog\Models\Attribute;
-use App\Domains\Catalog\Models\ProductVariant;
+use App\Domains\Catalog\Models\Category;
+use App\Domains\Catalog\Models\Product;
 use App\Domains\Catalog\Models\ProductAttribute;
+use App\Domains\Catalog\Models\ProductVariant;
 use App\Domains\Catalog\Models\ProductVariantDefinition;
 use App\Domains\Tenant\Models\Tenant;
 use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Str;
 use Tests\TestCase;
 
 class CartControllerTest extends TestCase
@@ -29,7 +34,7 @@ class CartControllerTest extends TestCase
                     'status' => 'active',
                     'items' => [],
                     'subtotal' => '0.00',
-                ]
+                ],
             ]);
     }
 
@@ -315,18 +320,73 @@ class CartControllerTest extends TestCase
             ->assertJsonValidationErrors(['cantidad' => 'El máximo que se puede agregar es 2.']);
     }
 
+    public function test_unlimited_inventory_can_be_reserved_updated_and_released_without_real_stock(): void
+    {
+        $variant = $this->createVariantForTenant(
+            'acme',
+            0,
+            '10.00',
+            'unlimited',
+            InventoryPolicy::Unlimited,
+        );
+
+        $response = $this->postJson('/api/tenants/acme/cart/items', [
+            'product_variant_id' => $variant->id,
+            'cantidad' => 100,
+        ])->assertOk();
+
+        $guestToken = $response->getCookie('guest_token', false)?->getValue();
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'stock_real' => 0,
+            'stock_reservado' => 100,
+        ]);
+
+        $this->call(
+            'PATCH',
+            "/api/tenants/acme/cart/items/{$variant->id}",
+            [],
+            ['guest_token' => $guestToken],
+            [],
+            ['HTTP_Accept' => 'application/json', 'CONTENT_TYPE' => 'application/json'],
+            json_encode(['cantidad' => 150]),
+        )->assertOk();
+
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'stock_real' => 0,
+            'stock_reservado' => 150,
+        ]);
+
+        $this->call(
+            'DELETE',
+            "/api/tenants/acme/cart/items/{$variant->id}",
+            [],
+            ['guest_token' => $guestToken],
+            [],
+            ['HTTP_Accept' => 'application/json'],
+        )->assertOk();
+
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'stock_real' => 0,
+            'stock_reservado' => 0,
+        ]);
+    }
+
     protected function createVariantForTenant(
         string $tenantCode,
         int $stock,
         string $price,
         string $slugPrefix = 'shirt',
+        InventoryPolicy $inventoryPolicy = InventoryPolicy::Tracked,
     ): ProductVariant {
         $tenant = Tenant::query()->where('codigo', $tenantCode)->first();
         if (! $tenant) {
             $this->createTenant($tenantCode, ucfirst($tenantCode), "{$tenantCode}.com");
         }
 
-        $category = \App\Domains\Catalog\Models\Category::query()->create([
+        $category = Category::query()->create([
             'tenant_code' => $tenantCode,
             'nombre' => "{$slugPrefix} category {$tenantCode}",
         ]);
@@ -342,6 +402,7 @@ class CartControllerTest extends TestCase
 
         return ProductVariant::query()->create([
             'producto_id' => $product->id,
+            'inventory_policy' => $inventoryPolicy->value,
             'slug' => "{$slugPrefix}-variant-".ProductVariant::query()->count(),
             'nombre' => ucfirst($slugPrefix).' Variant',
             'stock' => $stock,
@@ -352,21 +413,21 @@ class CartControllerTest extends TestCase
 
     protected function createTenant(string $codigo, string $nombre, string $dominio): Tenant
     {
-        $hdrKey = (string) \Illuminate\Support\Str::uuid();
-        $ftrKey = (string) \Illuminate\Support\Str::uuid();
+        $hdrKey = (string) Str::uuid();
+        $ftrKey = (string) Str::uuid();
 
-        $headerAttachment = \App\Domains\Attachable\Models\Attachment::create([
+        $headerAttachment = Attachment::create([
             'key' => $hdrKey,
-            'path' => 'tenants/' . $hdrKey . '.png',
+            'path' => 'tenants/'.$hdrKey.'.png',
             'filename' => 'logo_header.png',
-            'type' => \App\Domains\Attachable\Enums\AttachmentType::Image,
+            'type' => AttachmentType::Image,
             'mime_type' => 'image/png',
         ]);
-        $footerAttachment = \App\Domains\Attachable\Models\Attachment::create([
+        $footerAttachment = Attachment::create([
             'key' => $ftrKey,
-            'path' => 'tenants/' . $ftrKey . '.png',
+            'path' => 'tenants/'.$ftrKey.'.png',
             'filename' => 'logo_footer.png',
-            'type' => \App\Domains\Attachable\Enums\AttachmentType::Image,
+            'type' => AttachmentType::Image,
             'mime_type' => 'image/png',
         ]);
 

tests/Feature/Catalog/ProductControllerTest.php

@@ -4,6 +4,7 @@ namespace Tests\Feature\Catalog;
 
 use App\Domains\Attachable\Enums\AttachmentType;
 use App\Domains\Attachable\Models\Attachment;
+use App\Domains\Catalog\Enums\InventoryPolicy;
 use App\Domains\Catalog\Models\Attribute;
 use App\Domains\Catalog\Models\Brand;
 use App\Domains\Catalog\Models\Product;
@@ -768,6 +769,67 @@ class ProductControllerTest extends TestCase
         $response->assertJsonValidationErrors(['variant_id']);
     }
 
+    public function test_it_creates_an_unlimited_default_variant_and_exposes_inventory_fields(): void
+    {
+        $response = $this->postJson("/api/tenants/{$this->tenant->codigo}/productos", [
+            'categoria_id' => 1,
+            'brand_id' => $this->brand->id,
+            'slug' => 'unlimited-product',
+            'nombre' => 'Unlimited Product',
+            'precio' => 100,
+            'stock' => 0,
+            'inventory_policy' => InventoryPolicy::Unlimited->value,
+        ]);
+
+        $response->assertCreated();
+
+        $product = Product::query()->where('slug', 'unlimited-product')->firstOrFail();
+        $variant = $product->variants()->firstOrFail();
+        $this->assertSame(InventoryPolicy::Unlimited, $variant->inventory_policy);
+
+        $this->getJson("/api/tenants/{$this->tenant->codigo}/productos/{$product->id}")
+            ->assertOk()
+            ->assertJsonPath('data.variant.id', $variant->id)
+            ->assertJsonPath('data.variant.inventory_policy', InventoryPolicy::Unlimited->value)
+            ->assertJsonPath('data.variant.cantidad_maxima', null)
+            ->assertJsonPath('data.variant.cantidad_vendida', 0)
+            ->assertJsonPath('data.variants_map.0.inventory_policy', InventoryPolicy::Unlimited->value)
+            ->assertJsonPath('data.variants_map.0.cantidad_maxima', null)
+            ->assertJsonPath('data.variants_map.0.cantidad_vendida', 0);
+    }
+
+    public function test_it_rejects_invalid_or_updated_inventory_policies(): void
+    {
+        $this->postJson("/api/tenants/{$this->tenant->codigo}/productos", [
+            'categoria_id' => 1,
+            'brand_id' => $this->brand->id,
+            'slug' => 'invalid-policy',
+            'nombre' => 'Invalid Policy',
+            'precio' => 100,
+            'inventory_policy' => 'sometimes',
+        ])->assertUnprocessable()->assertJsonValidationErrors(['inventory_policy']);
+
+        $product = Product::query()->create([
+            'tenant_codigo' => $this->tenant->codigo,
+            'categoria_id' => 1,
+            'brand_id' => $this->brand->id,
+            'slug' => 'immutable-policy',
+            'nombre' => 'Immutable Policy',
+            'precio' => 100,
+        ]);
+        $variant = $product->variants()->create([
+            'stock' => 0,
+            'inventory_policy' => InventoryPolicy::Unlimited->value,
+        ]);
+
+        $this->putJson(
+            "/api/tenants/{$this->tenant->codigo}/productos/{$product->id}/variants/{$variant->id}",
+            ['inventory_policy' => InventoryPolicy::Tracked->value],
+        )->assertUnprocessable()->assertJsonValidationErrors(['inventory_policy']);
+
+        $this->assertSame(InventoryPolicy::Unlimited, $variant->fresh()->inventory_policy);
+    }
+
     private function createAttachment(string $path): Attachment
     {
         return Attachment::create([

tests/Feature/Integration/TelepagosWebhookTest.php

@@ -2,8 +2,12 @@
 
 namespace Tests\Feature\Integration;
 
+use App\Domains\Attachable\Enums\AttachmentType;
+use App\Domains\Attachable\Models\Attachment;
 use App\Domains\Auth\Models\User;
 use App\Domains\Cart\Models\Cart;
+use App\Domains\Catalog\Enums\InventoryPolicy;
+use App\Domains\Catalog\Models\Category;
 use App\Domains\Catalog\Models\Product;
 use App\Domains\Catalog\Models\ProductVariant;
 use App\Domains\Integration\Models\Integration;
@@ -14,6 +18,7 @@ use App\Domains\Tenant\Models\Tenant;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Str;
 use Tests\TestCase;
 
 class TelepagosWebhookTest extends TestCase
@@ -24,7 +29,7 @@ class TelepagosWebhookTest extends TestCase
     {
         parent::setUp();
 
-        config(['services.integrations.secret' => 'base64:' . base64_encode(random_bytes(32))]);
+        config(['services.integrations.secret' => 'base64:'.base64_encode(random_bytes(32))]);
         Cache::flush();
     }
 
@@ -113,6 +118,13 @@ class TelepagosWebhookTest extends TestCase
             'total' => 50,
         ]);
 
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'stock_real' => 9,
+            'stock_reservado' => 2,
+            'cantidad_vendida' => 1,
+        ]);
+
         $this->assertDatabaseMissing('compra_items', [
             'compra_id' => $newerPurchase->id,
         ]);
@@ -122,6 +134,60 @@ class TelepagosWebhookTest extends TestCase
         ]);
     }
 
+    public function test_transfer_webhook_buys_unlimited_inventory_without_reducing_real_stock(): void
+    {
+        $tenant = $this->createTenant('unlimited', 'Unlimited', 'unlimited.com.ar');
+        $this->configureTelepagosIntegration($tenant);
+        $user = User::factory()->create();
+        $variant = $this->createVariantForTenant(
+            'unlimited',
+            0,
+            '50.00',
+            'service',
+            InventoryPolicy::Unlimited,
+        );
+        $purchase = $this->createPendingTransferPurchase(
+            $tenant,
+            $user->id,
+            $variant->id,
+            3,
+            '87654321',
+        );
+
+        Http::fake([
+            'https://api.telepagos.com.ar/v2/auth/token' => Http::response([
+                'status' => 'ok',
+                'token' => 'test-token',
+                'expires_at' => now()->addHour()->toIso8601String(),
+            ]),
+            'https://api.telepagos.com.ar/v2/payment/cashin/7000' => Http::response([
+                'status' => 'ok',
+                'data' => [
+                    'amount' => 150,
+                    'operation_id' => 1,
+                    'transaction_id' => 'tx-unlimited',
+                    'buyer' => ['cuit' => '20876543219'],
+                ],
+            ]),
+        ]);
+
+        $this->postJson('/api/webhooks/telepagos/unlimited', ['id' => '7000'])
+            ->assertOk()
+            ->assertJsonPath('status', 'success');
+
+        $this->assertDatabaseHas('compras', [
+            'id' => $purchase->id,
+            'status' => Purchase::STATUS_PAID,
+        ]);
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'inventory_policy' => InventoryPolicy::Unlimited->value,
+            'stock_real' => 0,
+            'stock_reservado' => 0,
+            'cantidad_vendida' => 3,
+        ]);
+    }
+
     private function createPendingTransferPurchase(
         Tenant $tenant,
         int $userId,
@@ -184,8 +250,9 @@ class TelepagosWebhookTest extends TestCase
         int $stock,
         string $price,
         string $slugPrefix = 'shirt',
+        InventoryPolicy $inventoryPolicy = InventoryPolicy::Tracked,
     ): ProductVariant {
-        $category = \App\Domains\Catalog\Models\Category::query()->create([
+        $category = Category::query()->create([
             'tenant_code' => $tenantCode,
             'nombre' => "{$slugPrefix} category {$tenantCode}",
         ]);
@@ -201,6 +268,7 @@ class TelepagosWebhookTest extends TestCase
 
         return ProductVariant::query()->create([
             'producto_id' => $product->id,
+            'inventory_policy' => $inventoryPolicy->value,
             'slug' => "{$slugPrefix}-variant-".ProductVariant::query()->count(),
             'nombre' => ucfirst($slugPrefix).' Variant',
             'stock' => $stock,
@@ -211,21 +279,21 @@ class TelepagosWebhookTest extends TestCase
 
     private function createTenant(string $codigo, string $nombre, string $dominio): Tenant
     {
-        $hdrKey = (string) \Illuminate\Support\Str::uuid();
-        $ftrKey = (string) \Illuminate\Support\Str::uuid();
+        $hdrKey = (string) Str::uuid();
+        $ftrKey = (string) Str::uuid();
 
-        $headerAttachment = \App\Domains\Attachable\Models\Attachment::create([
+        $headerAttachment = Attachment::create([
             'key' => $hdrKey,
-            'path' => 'tenants/' . $hdrKey . '.png',
+            'path' => 'tenants/'.$hdrKey.'.png',
             'filename' => 'logo_header.png',
-            'type' => \App\Domains\Attachable\Enums\AttachmentType::Image,
+            'type' => AttachmentType::Image,
             'mime_type' => 'image/png',
         ]);
-        $footerAttachment = \App\Domains\Attachable\Models\Attachment::create([
+        $footerAttachment = Attachment::create([
             'key' => $ftrKey,
-            'path' => 'tenants/' . $ftrKey . '.png',
+            'path' => 'tenants/'.$ftrKey.'.png',
             'filename' => 'logo_footer.png',
-            'type' => \App\Domains\Attachable\Enums\AttachmentType::Image,
+            'type' => AttachmentType::Image,
             'mime_type' => 'image/png',
         ]);
 

tests/Feature/Purchase/StorePurchaseTest.php

@@ -2,14 +2,19 @@
 
 namespace Tests\Feature\Purchase;
 
+use App\Domains\Attachable\Enums\AttachmentType;
+use App\Domains\Attachable\Models\Attachment;
 use App\Domains\Auth\Models\User;
 use App\Domains\Cart\Models\Cart;
+use App\Domains\Catalog\Enums\InventoryPolicy;
+use App\Domains\Catalog\Models\Category;
 use App\Domains\Catalog\Models\Product;
 use App\Domains\Catalog\Models\ProductVariant;
 use App\Domains\Purchase\Models\Purchase;
 use App\Domains\Purchase\Services\CheckoutService;
 use App\Domains\Tenant\Models\Tenant;
 use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Str;
 use Tests\TestCase;
 
 class StorePurchaseTest extends TestCase
@@ -22,7 +27,7 @@ class StorePurchaseTest extends TestCase
         $user = User::factory()->create([
             'email' => 'buyer@example.com',
         ]);
-        $category = \App\Domains\Catalog\Models\Category::query()->create([
+        $category = Category::query()->create([
             'tenant_code' => 'sonder',
             'nombre' => 'Test Category',
         ]);
@@ -237,6 +242,13 @@ class StorePurchaseTest extends TestCase
         $checkoutService->confirmPurchase($purchase);
         $purchase->refresh()->markAsPaid();
 
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'stock_real' => 8,
+            'stock_reservado' => 0,
+            'cantidad_vendida' => 2,
+        ]);
+
         $this->assertSoftDeleted('carritos', [
             'id' => $purchase->cart_id,
         ]);
@@ -401,18 +413,48 @@ class StorePurchaseTest extends TestCase
             ->assertJsonValidationErrors(['cart_id']);
     }
 
+    public function test_it_confirms_unlimited_inventory_without_reducing_real_stock_and_is_idempotent(): void
+    {
+        $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
+        $user = User::factory()->create();
+        $variant = $this->createVariantForTenant(
+            'sonder',
+            0,
+            '50.00',
+            'unlimited',
+            InventoryPolicy::Unlimited,
+        );
+        $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 25);
+        $purchase->update(['payment_method' => 'transfer']);
+
+        $checkoutService = app(CheckoutService::class);
+        $purchase = $checkoutService->completePurchase($purchase);
+        $checkoutService->confirmPurchase($purchase);
+        $checkoutService->confirmPurchase($purchase);
+
+        $this->assertDatabaseHas('productos_variantes', [
+            'id' => $variant->id,
+            'inventory_policy' => InventoryPolicy::Unlimited->value,
+            'stock_real' => 0,
+            'stock_reservado' => 0,
+            'cantidad_vendida' => 25,
+        ]);
+        $this->assertDatabaseCount('compra_items', 1);
+    }
+
     protected function createVariantForTenant(
         string $tenantCode,
         int $stock,
         string $price,
         string $slugPrefix = 'shirt',
+        InventoryPolicy $inventoryPolicy = InventoryPolicy::Tracked,
     ): ProductVariant {
         $tenant = Tenant::query()->where('codigo', $tenantCode)->first();
         if (! $tenant) {
             $this->createTenant($tenantCode, ucfirst($tenantCode), "{$tenantCode}.com");
         }
 
-        $category = \App\Domains\Catalog\Models\Category::query()->create([
+        $category = Category::query()->create([
             'tenant_code' => $tenantCode,
             'nombre' => "{$slugPrefix} category {$tenantCode}",
         ]);
@@ -428,6 +470,7 @@ class StorePurchaseTest extends TestCase
 
         return ProductVariant::query()->create([
             'producto_id' => $product->id,
+            'inventory_policy' => $inventoryPolicy->value,
             'slug' => "{$slugPrefix}-variant-".ProductVariant::query()->count(),
             'nombre' => ucfirst($slugPrefix).' Variant',
             'stock' => $stock,
@@ -462,21 +505,21 @@ class StorePurchaseTest extends TestCase
 
     protected function createTenant(string $codigo, string $nombre, string $dominio): Tenant
     {
-        $hdrKey = (string) \Illuminate\Support\Str::uuid();
-        $ftrKey = (string) \Illuminate\Support\Str::uuid();
+        $hdrKey = (string) Str::uuid();
+        $ftrKey = (string) Str::uuid();
 
-        $headerAttachment = \App\Domains\Attachable\Models\Attachment::create([
+        $headerAttachment = Attachment::create([
             'key' => $hdrKey,
-            'path' => 'tenants/' . $hdrKey . '.png',
+            'path' => 'tenants/'.$hdrKey.'.png',
             'filename' => 'logo_header.png',
-            'type' => \App\Domains\Attachable\Enums\AttachmentType::Image,
+            'type' => AttachmentType::Image,
             'mime_type' => 'image/png',
         ]);
-        $footerAttachment = \App\Domains\Attachable\Models\Attachment::create([
+        $footerAttachment = Attachment::create([
             'key' => $ftrKey,
-            'path' => 'tenants/' . $ftrKey . '.png',
+            'path' => 'tenants/'.$ftrKey.'.png',
             'filename' => 'logo_footer.png',
-            'type' => \App\Domains\Attachable\Enums\AttachmentType::Image,
+            'type' => AttachmentType::Image,
             'mime_type' => 'image/png',
         ]);
 

tests/Unit/Catalog/ProductVariantInventoryTest.php

@@ -0,0 +1,153 @@
+<?php
+
+namespace Tests\Unit\Catalog;
+
+use App\Domains\Attachable\Enums\AttachmentType;
+use App\Domains\Attachable\Models\Attachment;
+use App\Domains\Catalog\Enums\InventoryPolicy;
+use App\Domains\Catalog\Models\Category;
+use App\Domains\Catalog\Models\Product;
+use App\Domains\Catalog\Models\ProductVariant;
+use App\Domains\Tenant\Models\Tenant;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Str;
+use Tests\TestCase;
+
+class ProductVariantInventoryTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private Product $product;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $headerAttachment = $this->createAttachment('header.png');
+        $footerAttachment = $this->createAttachment('footer.png');
+
+        $tenant = Tenant::query()->create([
+            'codigo' => 'inventory-test',
+            'nombre' => 'Inventory Test',
+            'dominio' => 'inventory.test',
+            'primary_color' => '#111111',
+            'secondary_color' => '#222222',
+            'danger_color' => '#333333',
+            'success_color' => '#28a745',
+            'header_bg_color' => '#444444',
+            'footer_bg_color' => '#444444',
+            'header_logo_id' => $headerAttachment->id,
+            'footer_logo_id' => $footerAttachment->id,
+        ]);
+
+        $category = Category::query()->create([
+            'tenant_code' => $tenant->codigo,
+            'nombre' => 'Inventory',
+        ]);
+
+        $this->product = Product::query()->create([
+            'tenant_codigo' => $tenant->codigo,
+            'categoria_id' => $category->id,
+            'slug' => 'inventory-product',
+            'nombre' => 'Inventory Product',
+            'precio' => 100,
+        ]);
+    }
+
+    public function test_it_defaults_to_tracked_inventory_with_no_sales(): void
+    {
+        $variant = $this->createVariant(5);
+
+        $this->assertSame(InventoryPolicy::Tracked, $variant->inventory_policy);
+        $this->assertSame(5, $variant->availableQuantity());
+        $this->assertSame(0, $variant->cantidad_vendida);
+        $this->assertTrue($variant->isAvailableForSale());
+    }
+
+    public function test_tracked_inventory_cannot_reserve_more_than_available_stock(): void
+    {
+        $variant = $this->createVariant(5);
+        $variant->reserveStock(3);
+
+        $this->assertSame(2, $variant->fresh()->availableQuantity());
+
+        $this->expectException(\InvalidArgumentException::class);
+        $variant->reserveStock(3);
+    }
+
+    public function test_unlimited_inventory_can_reserve_more_than_real_stock(): void
+    {
+        $variant = $this->createVariant(0, InventoryPolicy::Unlimited);
+        $variant->reserveStock(50);
+
+        $variant->refresh();
+        $this->assertNull($variant->availableQuantity());
+        $this->assertSame(50, $variant->stock_reservado);
+        $this->assertTrue($variant->isAvailableForSale());
+    }
+
+    public function test_buying_tracked_inventory_consumes_stock_and_records_the_sale(): void
+    {
+        $variant = $this->createVariant(10);
+        $variant->reserveStock(4);
+        $variant->buy(3);
+
+        $variant->refresh();
+        $this->assertSame(7, $variant->stock_real);
+        $this->assertSame(1, $variant->stock_reservado);
+        $this->assertSame(3, $variant->cantidad_vendida);
+    }
+
+    public function test_buying_unlimited_inventory_preserves_real_stock_and_records_the_sale(): void
+    {
+        $variant = $this->createVariant(0, InventoryPolicy::Unlimited);
+        $variant->reserveStock(4);
+        $variant->buy(3);
+
+        $variant->refresh();
+        $this->assertSame(0, $variant->stock_real);
+        $this->assertSame(1, $variant->stock_reservado);
+        $this->assertSame(3, $variant->cantidad_vendida);
+    }
+
+    public function test_buy_requires_enough_reserved_stock(): void
+    {
+        $variant = $this->createVariant(10);
+        $variant->reserveStock(1);
+
+        $this->expectException(\InvalidArgumentException::class);
+        $variant->buy(2);
+    }
+
+    public function test_inventory_policy_cannot_change_after_creation(): void
+    {
+        $variant = $this->createVariant(10);
+        $variant->inventory_policy = InventoryPolicy::Unlimited;
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('La politica de inventario no puede modificarse.');
+        $variant->save();
+    }
+
+    private function createVariant(
+        int $stock,
+        InventoryPolicy $inventoryPolicy = InventoryPolicy::Tracked,
+    ): ProductVariant {
+        return ProductVariant::query()->create([
+            'producto_id' => $this->product->id,
+            'stock' => $stock,
+            'inventory_policy' => $inventoryPolicy->value,
+        ]);
+    }
+
+    private function createAttachment(string $filename): Attachment
+    {
+        return Attachment::query()->create([
+            'key' => (string) Str::uuid(),
+            'path' => 'tests/'.$filename,
+            'filename' => $filename,
+            'type' => AttachmentType::Image,
+            'mime_type' => 'image/png',
+        ]);
+    }
+}