I want to take the test and I’m not sure what code book the state of Tennessee is on and what I need to do/have (requirements) to be able to take the exam.
The State itself is still enforcing the 2017 with a few State amendments however many jurisdictions (City/County, etc) have adopted later versions of the NEC and the requirements for obtaining a license on those jurisdictions vary. There are various "State" licenses, one of which is a C-E license which does allow you to obtain licensing in any jurisdiction.