How to make mocha watch, compile and test coffeescript with dependencies on save

Question

I'm working on a project that uses coffeescript for development and testing. I run the tests in node with mocha's --watch flag on so I can have the tests run automatically when I make changes.

While this works to some extent, only the ./test/test.*.coffee files are recompiled when something is saved. This is my directory structure:

/src/coffee
-- # Dev files go here
/test/
-- # Test files go here

The mocha watcher responds to file changes inside the /src and /test directories, but as long as only the files in the /test directory are recompiled continuous testing is kind of borked. If I quit and restart the watcher process the source files are also recompiled. How can I make mocha have the coffee compiler run over the development files listed as dependencies inside the test files on each run?

Answer 1

Here is my answer using grunt.js

You will have to install grunt and few additionnal packges.

npm install grunt grunt-contrib-coffee grunt-simple-mocha grunt-contrib-watch

And write this grunt.js file:

module.exports = function(grunt) {

  grunt.loadNpmTasks('grunt-contrib-coffee');
  grunt.loadNpmTasks('grunt-simple-mocha');
  grunt.loadNpmTasks('grunt-contrib-watch');

  grunt.initConfig({
    coffee:{
      dev:{
        files:{
          'src/*.js':'src/coffee/*.coffee',
        }
      },
      test:{
        files:{          
          'test/test.*.js':'test/test.*.coffee'
        }
      }
    },
    simplemocha:{
      dev:{
        src:"test/test.js",
        options:{
          reporter: 'spec',
          slow: 200,
          timeout: 1000
        }
      }
    },
    watch:{
      all:{
        files:['src/coffee/*', 'test/*.coffee'],
        tasks:['buildDev', 'buildTest', 'test']
      }
    }
  });

  grunt.registerTask('test', 'simplemocha:dev');
  grunt.registerTask('buildDev', 'coffee:dev');
  grunt.registerTask('buildTest', 'coffee:test');
  grunt.registerTask('watch', ['buildDev', 'buildTest', 'test', 'watch:all']);

};

Note: I didn't have some detials on how you build / run your tests so you certainly have to addapt ;)

Then run the grunt watch task :

$>grunt watch

Answer 2

Using a Cakefile with flour :

flour = require 'flour'
cp    = require 'child_process'

task 'build', ->
    bundle 'src/coffee/*.coffee', 'lib/project.js'

task 'watch', ->
    invoke 'build'
    watch 'src/coffee/', -> invoke 'build'

task 'test', ->
    invoke 'watch'
    cp.spawn 'mocha --watch', [], {stdio: 'inherit'}

Mocha already watches the test/ folder, so you only need to watch src/ .