You can consider the following sample test cases for payment gateway testing.
- Change the language of the payment gateway during the payment process.
- Check whether the important components are retrieved or not after the payment.
- Check the response if the payment gateway stops responding.
- Check what happens in the back end and if the session ends.
- Check what happens if the payment fails.
- Check if the database stores the card details or not.
- Check the errors during the payment process.
- Check the response after turning the pop up blocker on and off.
- Check the buffer page between the payment gateway and application.
- Check what happens after successful payment.
- Verify the transaction process.
- Check the messages and verify it after successful payment process.
- Check the currency format of the payment.
- Check if the payment option opens the respective payment gateway after selection.
- Verify the default debit card option.
References – https://www.360logica.com/blog/