add inventory and supply logic

tests/Unit/Services/Inventory/SupplierServiceTest.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Tests\Unit\Services\Inventory;
+
+use App\Services\Inventory\SupplierService;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\DB;
+use Tests\TestCase;
+
+class SupplierServiceTest extends TestCase
+{
+    use RefreshDatabase;
+
+    public function test_create_supplier(): void
+    {
+        $service = new SupplierService();
+        $result = $service->create([
+            'name' => 'Supplier A',
+            'email' => 'a@example.com',
+        ]);
+
+        $this->assertTrue($result['ok']);
+        $this->assertDatabaseHas('suppliers', ['name' => 'Supplier A']);
+    }
+
+    public function test_update_supplier(): void
+    {
+        $id = DB::table('suppliers')->insertGetId([
+            'name' => 'Supplier B',
+            'created_at' => now(),
+            'updated_at' => now(),
+        ]);
+
+        $service = new SupplierService();
+        $result = $service->update($id, ['name' => 'Supplier Updated']);
+
+        $this->assertTrue($result['ok']);
+        $this->assertDatabaseHas('suppliers', ['id' => $id, 'name' => 'Supplier Updated']);
+    }
+}