Why IAP product count is empty?

I added three inapp purchases to the app and they have "Ready to submit" status.

Can I test them before submitting the application on the simulator?

I'm asking it because

response.products 

are empty, when I'm using this method.

func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
        if response.products.count != 0 {
            for product in response.products {
                print(product.localizedTitle)
            }
        }
    }