Ruby Guard style testing with Node.js

Great way for automating the running of tests / specs when building a JavaScript project. I'm using mocha for the the tests but have a nice little Makefile for building the project and running tests / coverage.

I tend to keep all my dev/library files under either a lib/ or a src/ folder and my test files under either a test/ or spec/ folder.

First create a small Node.js based script using nodewatch for watching either your unit tests or source directory such as utils/watcher.js.

var watch = require('nodewatch');
var util = require('util');
var exec = require('child_process').exec;

watch
  .add("./test", true)
  .add("./src", true)
  .onChange(function(file, prev, curr, action) {

    exec("make test", function(error, stdout, stderr) {

      util.print('stdout: ' + stdout);
      util.print('stderr: ' + stderr);

      if (error !== null) {
        console.log('exec error: ' + error);
      }

    });

  });

Now create a Makefile to simplify a few command. While this is not necessary it's a good habit to get into and means you can always run the 'make test' command at any point to test.

test:
    mocha --recursive --reporter spec --ui bdd --colors --grunt

watch:
    node utils/watcher.js

.PHONY test watch

The benefits here are Mocha also gives me growl notifications so I don't even need to leave my editor and I can see these fire off each time I save a file in either my dev or test folders.