Grunt Events

a_simple.js

/*
 * A) Simple Watch Events
 */
module.exports = function(grunt) {
  grunt.initConfig({
    nodeunit: {
      files: ['test/**/*.js'],
    },
    watch: {
      test: {
        files: ['<%= nodeunit.files %>'],
        tasks: ['nodeunit']
      }
    }
  });
  grunt.event.on(['watch', '*'], function(filepath) {
    // Do something when file added/changed/deleted

    // How helpful is this event? The watch.test.tasks above will still
    // run regaurdless.

    // What if I only wanted to run nodeunit on the corresponding test?
    // I would need to create a watch target for every file.

    // So simple events would be helpful for notifications but not useful
    // for much else.
  });
  grunt.registerTask('default', ['nodeunit']);
};

b_per-target.js

/*
 * B) Integrated Watch Events
 */
module.exports = function(grunt) {
  grunt.initConfig({
    nodeunit: {
      files: ['test/**/*.js'],
    },
    watch: {
      test: {
        files: ['<%= nodeunit.files %>'],
        tasks: ['nodeunit'],
        // events can be configured per target
        on: { 'watch.*': onWatch }
      }
    }
  });

  function onWatch(filepath) {
    // filepath would be the file edited upon this event
    // this.event === the event fired: changed, added, deleted

    // do nothing here and it would run the tasks as normal
    // and act as a notification

    // only run the tasks for the edited file
    // this.files() would set an array of files to run the task on
    this.files([filepath]);

    // or a set of tests setup for this src file
    var testDir = require('path').basename(filepath, '.js');
    this.files(['test/' + testDir + '/*.js']);

    // run the jshint task instead of nodeunit
    // this.tasks() would set an array of tasks to run on the fiels
    this.tasks(['jshint']);
  }

  grunt.registerTask('default', ['nodeunit']);
};

c_all-targets.js

/*
 * C) External Watch Events (not integrated with config)
 */
module.exports = function(grunt) {
  grunt.initConfig({
    nodeunit: {
      files: ['test/**/*.js'],
    },
    watch: {
      test: {
        files: ['<%= nodeunit.files %>'],
        tasks: ['nodeunit']
      }
    }
  });

  // One event listener for all watch targets
  grunt.event.on('watch.*', function(filepath) {
    // filepath would be the file edited upon this event
    // this.event === the event fired: changed, added, deleted

    // do nothing here and it would run the tasks as normal
    // and act as a notification

    // only run the tasks for the edited file
    // this.files() would set an array of files to run the task on
    this.files([filepath]);

    // or a set of tests setup for this src file
    var testDir = require('path').basename(filepath, '.js');
    this.files(['test/' + testDir + '/*.js']);

    // run the jshint task instead of nodeunit
    // this.tasks() would set an array of tasks to run on the fiels
    this.tasks(['jshint']);
  });

  grunt.registerTask('default', ['nodeunit']);
};