add addProductStock method to Store model and update `OrderProduc…

…tTest` and `OrderTest` to use it

src/models/Store.php

@@ -146,6 +146,16 @@ public function validate(): array
         return $errors;
     }
 
+    public function addProductStock(int $product_id, int $quantity): bool
+    {
+        $query = "INSERT INTO store_product (store_id, product_id, stock_level) VALUES (:store_id, :product_id, :quantity)
+                  ON DUPLICATE KEY UPDATE stock_level = stock_level + :quantity";
+        $params = ['store_id' => $this->store_id, 'product_id' => $product_id, 'quantity' => $quantity];
+        $result = self::query($query, $params);
+
+        return $result;
+    }
+
     public function getProductStock(int $product_id): int
     {
         $query = "SELECT stock_level FROM store_product WHERE store_id = :store_id AND product_id = :product_id;";

tests/OrderProductTest.php

@@ -64,6 +64,9 @@ public function setUp(): void
             throw new Exception('Unable to save product');
         }
 
+        // Update stock level for the product
+        $this->dummy_store->addProductStock($this->dummy_product->getProductID(), 10);
+
         // Create dummy order line items
         $this->line_items = [
             new OrderProduct($this->dummy_product->getProductID(), "medium", "oat", 2, 5.0)

tests/OrderTest.php

@@ -70,6 +70,10 @@ public function setUp(): void
             throw new Exception('Unable to save product 2');
         }
 
+        // Add stock to the store for the products
+        $this->dummy_store->addProductStock($product1->getProductID(), 10);
+        $this->dummy_store->addProductStock($product2->getProductID(), 10);
+
         // Create dummy order line items
         $this->line_items = [
             new OrderProduct($product1->getProductID(), "medium", "oat", 2, 5.0),