Test credit cards for authorize.net payment gateway

I have created a test account on authorize.net and trying to create different kinds (authorize, purchase, etc.) of transactions on the api using gem active_merchant.

The transactions are working fine for success cases. The problem is i am not able to find the Credit Card details anywhere in the Docs for which the transactions will return error in response.

I have also searched for the test credit cards at various places, but no success so far. Any helpful links/suggestions will be appreciated.

Thanks