In order for you to test Pagos en efectivo (Argentina) payment method successfully, you don’t need any given test data.
Pagos en efectivo Payment Flow
The Customer enters the required details: email address, first name and last name.
The Customer receives a voucher containing the payment details. In order to complete the payment, he needs to print the voucher and pay it at any PagoFácil / Rapipago / Provincia Pagos / CobroExpress branch in his area.