Cisco has a built in tool that allows you to test AAA server connectivity.  It is included in both the CLI and the ASDM.  This tool is useful when you are setting up a AAA server because you don't have to login and out of the device in order to test the connectivity.

The CLI command is:
test aaa-server authentication SERVERNAME [more]

After entering this command you will be prompted to enter the server IP address, and a username and password.

The packet-tracer command is another tool that comes in handy when testing access-lists and VPN configurations.  It simulates a packet that transverses through the ASA and prints out the each step it takes and points out where it is failing.

To trace a HTTP packet from the inside address of to outside address of the command would be:
packet-tracer input inside tcp www www detailed