Handle missing products without a type error

Server/App/Model/Product.php

@@ -28,13 +28,13 @@ public function __construct(ContainerInterface $container)
         $this->db = $container->get(Database::class);
     }
 
-    public function get(int $productId): stdClass
+    public function get(int $productId): ?stdClass
     {
         $stmt = $this->db->prepare(self::QUERY_GET_PRODUCT);
         $stmt->bindValue('productId', $productId, PDO::PARAM_INT);
         $stmt->execute();
 
-        return $stmt->fetchObject();
+        return $stmt->fetchObject() ?: null;
     }
 
     public function search(string $keywords, int $offset = null, int $limit = null): array

Test/Server/App/Model/ProductTest.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Lifyzer\Test\Server\App\Model;
+
+use Lifyzer\Server\App\Model\Product;
+use PDO;
+use PHPUnit\Framework\TestCase;
+use Psr\Container\ContainerInterface;
+
+/** @requires extension pdo_sqlite */
+class ProductTest extends TestCase
+{
+    private function model(): Product
+    {
+        $db = new PDO('sqlite::memory:');
+        $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+        $db->exec('CREATE TABLE product (id INTEGER PRIMARY KEY, product_name TEXT)');
+        $db->exec("INSERT INTO product VALUES (1, 'Apple')");
+        $container = new class($db) implements ContainerInterface {
+            private $db;
+            public function __construct(PDO $db) { $this->db = $db; }
+            public function get($id) { return $this->db; }
+            public function has($id): bool { return true; }
+        };
+        return new Product($container);
+    }
+
+    public function testExistingProductRetainsItsData(): void
+    {
+        $product = $this->model()->get(1);
+        self::assertSame('Apple', $product->product_name);
+    }
+
+    public function testMissingProductCanBeHandledByTheController(): void
+    {
+        self::assertNull($this->model()->get(999));
+    }
+}