javascript - New to Grunt - Can't find any tasks

Question

I have followed the Getting started guide at http://gruntjs.com/getting-started, but I can't seem to run grunt (running grunt-cli v0.1.9 and grunt 0.4.1 on Mac OS X 10.8.5, installed with npm).

This is my Gruntfile.js:

module.exports = function(grunt) {
    grunt.registerTask('test', 'Test task.', function() {
        grunt.log.writeln('Lorem ipsum dolor sit amet.');
    });
};

When I try to run grunt with "grunt test" I just get:

Warning: Task "test" not found. Use --force to continue.

Aborted due to warnings.

I have also tried installing plugins like uglify (following the examples in Getting started), but no tasks seem to work. What am I doing wrong?