Can't make sense of the Mocha 'Getting Started' instructions

Trying to use Mocha for unit testing. The Getting Started instructions are straightforward enough at first:

• Install Mocha with npm install mocha
• Create a file called test.js
• Edit the file and paste (some predefined stuff) into it

All great, so far. But then, "Back in the terminal":

Array
    #indexOf
    ...etc

Ok, I'm totally baffled. Obviously, it doesn't mean to type this on the command line. But I tried running node and doing a require('<test file>'); to no avail. It just says the function describe is not defined. What does this last instruction really mean? What am I really supposed to do to get this framework going so I can use it for unit testing?