'npm test' fails to load coffeescript files

[raboof]

When I 'npm test', I get:

> presentz.org@1.0.0 test /home/aengelen/dev/presentz.org
> node_modules/mocha/bin/mocha --compilers coffee:coffee-script --reporter spec

/home/aengelen/dev/presentz.org/node_modules/coffee-script/lib/coffee-script/coffee-script.js:244
        throw new Error("Use CoffeeScript.register() or require the coffee-script/register module to require " + ext + " files.");
        ^

Error: Use CoffeeScript.register() or require the coffee-script/register module to require .coffee files.
    at Object.(anonymous function).base.(anonymous function) [as .coffee] (/home/aengelen/dev/presentz.org/node_modules/coffee-script/lib/coffee-script/coffee-script.js:244:15)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at /home/aengelen/dev/presentz.org/node_modules/mocha/lib/mocha.js:222:27
    at Array.forEach (native)
    at Mocha.loadFiles (/home/aengelen/dev/presentz.org/node_modules/mocha/lib/mocha.js:219:14)
    at Mocha.run (/home/aengelen/dev/presentz.org/node_modules/mocha/lib/mocha.js:487:10)
    at Object.<anonymous> (/home/aengelen/dev/presentz.org/node_modules/mocha/bin/_mocha:459:18)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:509:3
npm ERR! Test failed.  See above for more details.