Test cards are on the portal when you go to recharge your account in test mode
When first integrating our APIs, its best to switch your account on test mode. Then go to MY wallet-->ADD CARD-->clcik on the link " Click here for a list of valid test credit cards " ---> enter one of the copied card number and fill up the field.
In test mode you will receive an email with the verification amount to enter as the second step to activate the "test cards". Click and "verify" and enter the amount sent to your email. ONLY then can you add test BALANCE to your account.