Is there a tutorial on how to run the system tests?

CodeIgniter 3 comes with a folder full of tests. Has anyone written instructions on how I can run those tests? 

My first thought was that they would run in the browser, so I've got a http://codeigniter.local/ running, but I don't understand how to run the tests.

My next thought was that they need to run from the command line. If so, is there a tutorial somewhere that will explain what command to run, and from which folder? 

I am specifically interested in running the database/query_builder tests if that helps.

Thanks,