For MyBank payment method there aren’t any test data available, but you can see how it works with the payment flow given below.
MyBank Payment Flow
The Customer enters his email address, name, and chooses his preferred bank from the list.
The customer verifies the payment details, logins to his account using his username and password and confirms the payment. Please keep in mind there is an order expiration time in which the customer may complete the payment, after which the payment will be expired.
Upon completion of the payment flow the customer is redirected back to your ReturnURL.