Any way to test trials before going live (React Native)?

I’m adding iOS Introductory Offers, and I would like to test before going live. However, when following the guide in the docs, the `discounts` field on the product is an empty array. How do I test this introductory offer before going live?

Example of the code I’m using for reference:

const purchaseDiscountedIOSPackage = async (purchasePackage) => {
  const product = purchasePackage.product;
  const discount = product.discounts?.[0];
  // product.discounts is empty
  if (!discount) {
    throw new Error('No discount found on producct');
  }
  const paymentDiscount = await Purchases.getPromotionalOffer(product, discount);
  if (!paymentDiscount) {
    throw new Error('No payment discount');
  }

  try {
    const purchaseMade = await Purchases.purchaseDiscountedPackage(pkg, paymentDiscount);
    return purchaseMade.customerInfo;
  } catch (e) {
    if (!e.userCancelled) {
      throw e;
    } else {
      throw new Error('ignore');
    }
  }
};

const purchase = async () => {
  const offering = (await Purchases.getOfferings()).current;
  const package = offering.availablePackages[0];
  if (package) {
    await purchaseDiscountedIOSPackage(package);
  }
};