Stole this one from the Cisco Reader Tip - very handy! Allows you to test AAA user authentication from the ASA command-line:
ASA# test aaa-server [authentication|authorization] <aaa_server_group> [host
<name>|<host_ip>] username <user> password
<pass>
For example:
ASA# test aaa-server authentication TACGroup username johndoe password cisco123
if authentication is successful - INFO: Authentication Successful
if authentication fails - ERROR: Authentication Rejected: Unspecified

