Mailspring/app/build/tasks/create-mac-dmg.js

const path = require('path');
const createDMG = require('electron-installer-dmg');

module.exports = grunt => {
  grunt.registerTask('create-mac-dmg', 'Create DMG for Mailspring', function pack() {
    const done = this.async();
    const dmgPath = path.join(grunt.config('outputDir'), 'Mailspring.dmg');
    createDMG({
      appPath: path.join(grunt.config('outputDir'), 'Mailspring-darwin-x64', 'Mailspring.app'),
      name: 'Mailspring',
      background: path.resolve(
        grunt.config('appDir'),
        'build',
        'resources',
        'mac',
        'DMG-background.png'
      ),
      icon: path.resolve(grunt.config('appDir'), 'build', 'resources', 'mac', 'mailspring.icns'),
      overwrite: true,
      out: grunt.config('outputDir'),
    }).then(
      () => {
        grunt.log.writeln(`>> Created ${dmgPath}`);
        done(null);
      },
      err => {
        done(err);
      }
    );
  });
};