I am using Woocommerce Word press plugin to integrate payment gateway. https://wordpress.org/plugins/woocommerce/
Created my Test Mode account in Pay U Money and recieved key and salt id to configure in the plugin.
After adding product to page in test mode, post view cart when go ahead for checkout, it says thank you ....and then redirect page to https://test.payu.in/_payment with message as "Sorry, Some Problem Occurred."