Splunk Enterprise is implemented, but we would like to do testing just to make sure everything is working correctly. Looking for a Splunk functional test plan...
What version of Splunk are you running? In 6.5, the Monitoring Console ships with a Health Check. If that is configured on one of the nodes in your environment, it will allow you to run a health check against all instances:
If you haven't used that before, please be sure to read through the documents on where it should be configured:
If you do not have 6.5, the predecessor to the Monitor Console, Distributed Management Console, had a number of dashboards that could help you evaluate the health of the environment.