No, you do not need to change any code. Its all processed from the backend.
Usually for development purposes we use the cash on delivery or check / money transfer method. Therefore, you just need to enable this method from the backend.
To test credit cards, activate the “Saved CC” payment method and during the check use the VISA test credit card, card number 4111111111111111 with any future date for the Expiration Date and any cvv number
In addition, for the proper integration of payment gateways, you will need to purchase a payment gateway, which together with it will provide the Magento module. This payment method will have 2 test and live modes that are configured with banckend. Thus, in test mode, you can continue development and testing.
Similarly with Paypal. Yo can set up a test Sandbox account. The module already exists.
Deependra singh
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