ShoppingCart.cs

public void PurchaseItem(
    string itemUrl,
    string itemPrice,
    ClientLoginInfo clientLoginInfo,
    ClientPurchaseInfo clientPurchaseInfo)
{
    this.itemPage.Navigate(itemUrl);
    this.itemPage.ClickBuyNowButton();
    this.previewShoppingCartPage.ClickProceedToCheckoutButton();
    this.signInPage.Login(clientLoginInfo.Email, clientLoginInfo.Password);
    this.shippingAddressPage.FillShippingInfo(clientPurchaseInfo);
    this.shippingAddressPage.ClickDifferentBillingCheckBox(clientPurchaseInfo);
    this.shippingAddressPage.ClickContinueButton();
    this.shippingPaymentPage.ClickBottomContinueButton();
    this.shippingAddressPage.FillBillingInfo(clientPurchaseInfo);
    this.shippingAddressPage.ClickContinueButton();
    this.shippingPaymentPage.ClickTopContinueButton();
    double totalPrice = double.Parse(itemPrice);
    this.placeOrderPage.AssertOrderTotalPrice(totalPrice);
}