Payment service providers offer you the opportunity to test the function with their test or sandbox accounts. In the Frisbii Media Merchant Backend, the test data can be entered in the stage account in order to test payments and transactions before going live.
With Stripe you have the option of using test payment methods in the checkout.
With PayPal and Amazon Pay, sandbox accounts (test customers) can be created and used in the checkout.
The following Knowledge Base entries will guide you step by step through the process of setting up a test account:
PayPal: Create a PayPal sandbox account
Amazon Pay: Amazon Pay test accounts
Stripe test payment method: https://docs.stripe.com/testing