Grunt debugging from Webstorm

You have to run grunt-cli as a Node application:

• Create a new Node.js Run/Debug configuration: Run->Edit configurations…
• In Path to Node choose your node binary, ie: /Users/someuser/nvm/v0.10.5/bin/node
• In Working Directory, choose your Gruntfile.js directory, ie /Projects/someproject
• In Path to Node App JS File, choose your Grunt CLI path (you can choose the grunt-cli symlink created on your node bin directory, WebStorm will use the symlink target), ie: /Users/someuser/nvm/v0.10.5/lib/node_modules/grunt-cli/bin/grunt
  (C:\Users\someuser\AppData\Roaming\npm\node_modules\grunt-cli\bin\grunt on Windows 7)
• In Application parameters enter the Grunt task to run, eg default or test

Click on Run or Debug and you are done 🙂