Test account details will vary between payment service providers - they each have their own set of test details, though there are some "common" ones used across providers. Most PSPs have pages online where they supply such test details. 


See below links to pages with test details for some of the PSPs


Authorize.net: https://developer.authorize.net/hello_world/testing_guide/


Braintree: https://developers.braintreepayments.com/guides/credit-cards/testing-go-live/php


CyberSource: https://www.cybersource.com/developers/other_resources/quick_references/test_cc_numbers/


Moneris: https://developer.moneris.com/More/Testing/Testing%20a%20Solution


Sage Pay: https://www.sagepay.co.uk/support/12/36/test-card-details-for-your-test-transactions


Stripe: https://stripe.com/docs/testing


Worldpay: http://support.worldpay.com/support/kb/bg/testandgolive/tgl5103.html