What is test mode used for?
The test mode allows you to simulate a real payment without having to perform it.
In card payments, after redirection from the store, you will see the buttons for simulating confirmation or declining payments.
In basic payments, in the transaction panel, instead of a redirection to the bank, you will see the "Save" which will change the status of the test transaction to a paid one.
The purpose of the test is to check whether, after payment, the order in the store has been changed to paid.