Gruntfile.js

module.exports = function (grunt) {
  grunt.initConfig({
    // Builds Sass
    sass: {
      dev: {
        options: {
          style: 'expanded',
          sourcemap: true,
          includePaths: [
            'govuk_modules/govuk_template/assets/stylesheets',
            'govuk_modules/govuk_frontend_toolkit/stylesheets',
            'govuk_modules/govuk-elements-sass/'
          ],
          outputStyle: 'expanded'
        },
        files: [{
          expand: true,
          cwd: 'app/assets/sass',
          src: ['*.scss'],
          dest: 'public/stylesheets/',
          ext: '.css'
        }]
      }
    },

    // Copies templates and assets from external modules and dirs
    sync: {
      assets: {
        files: [{
          expand: true,
          cwd: 'app/assets/',
          src: ['**/*', '!sass/**'],
          dest: 'public/'
        }],
        ignoreInDest: '**/stylesheets/**',
        updateAndDelete: true
      },
      govuk: {
        files: [{
          cwd: 'node_modules/govuk_frontend_toolkit/',
          src: '**',
          dest: 'govuk_modules/govuk_frontend_toolkit/'
        },
        {
          cwd: 'node_modules/govuk_template_jinja/assets/',
          src: '**',
          dest: 'govuk_modules/govuk_template/assets/'
        },
        {
          cwd: 'node_modules/govuk_template_jinja/views/layouts/',
          src: '**',
          dest: 'govuk_modules/govuk_template/views/layouts/'
        },
        {
          cwd: 'node_modules/govuk-elements-sass/public/sass/',
          src: ['**', '!node_modules', '!elements-page.scss', '!elements-page-ie6.scss', '!elements-page-ie7.scss', '!elements-page-ie8.scss', '!main.scss', '!main-ie6.scss', '!main-ie7.scss', '!main-ie8.scss', '!prism.scss'],
          dest: 'govuk_modules/govuk-elements-sass/'
        }]
      },
      govuk_template_jinja: {
        files: [{
          cwd: 'govuk_modules/govuk_template/views/layouts/',
          src: '**',
          dest: 'lib/'
        }]
      }
    },

    // Watches assets and sass for changes
    watch: {
      css: {
        files: ['app/assets/sass/**/*.scss'],
        tasks: ['sass'],
        options: {
          spawn: false
        }
      },
      assets: {
        files: ['app/assets/**/*', '!app/assets/sass/**'],
        tasks: ['sync:assets'],
        options: {
          spawn: false
        }
      }
    },

    // nodemon watches for changes and restarts app
    nodemon: {
      dev: {
        script: 'server.js',
        options: {
          ext: 'js, json',
          ignore: ['node_modules/**', 'app/assets/**', 'public/**'],
          args: grunt.option.flags()
        }
      }
    },

    concurrent: {
      target: {
        tasks: ['watch', 'nodemon'],
        options: {
          logConcurrentOutput: true
        }
      }
    }
  })

  ;[
    'grunt-sync',
    'grunt-contrib-watch',
    'grunt-sass',
    'grunt-nodemon',
    'grunt-concurrent'
  ].forEach(function (task) {
    grunt.loadNpmTasks(task)
  })

  grunt.registerTask('generate-assets', [
    'sync',
    'sass'
  ])

  grunt.registerTask('default', [
    'generate-assets',
    'concurrent:target'
  ])

  grunt.registerTask(
    'test',
    'default',
    function () {
      grunt.log.writeln('Test that the app runs')
    }
  )
}