Although BrowserStig may be used for other automation purposes, it's main purpose is to be used for functional testing. As mentioned before, you can use browserstig.js standalone without the cli. This would allow you to import browserstig.js into any javascript testing framework. However, the stig cli is designed to help you start testing immediately with minimal setup.
If you have used the karma test runner, you will be familiar with the stig cli. Really, the stig cli just wraps the karma test runner. The supported test styles are 'mocha', 'jasmine' and 'qunit'. However, this documentation only covers testing with mocha.