public void PlaceOrder_With_PromotionalOffer()
{
var productPurchaseOrder = GetMockPurchaseProductOrder();
purchaseOrderRepo.AddProductToPurchaseOrder(productPurchaseOrder);
purchaseOrderRepo.PlaceOrder();
Assert.IsTrue(purchaseOrderRepo.GetPurchasedProducts().Count == 2 && purchaseOrderRepo.GetAnyPromotionalOfferFreeProduct().Count == 1);
}