Warning 'The API interface has changed' when running Karma on grunt

Question

When running karma from a grunt task I get the following warning:

Running "karma:unit" (karma) task
Warning: The api interface has changed. Please use 
  server = new Server(config, [done])
  server.start()
instead. Use --force to continue.

Aborted due to warnings.

I have tested running karma with my configuration, both using the 'run' and 'start' karma commands and they seem to work fine.

Using grunt --force can complete the task, but it completes with warnings.

This are the versions that I'm currently using:

• Karma 0.13.0
• Grunt 0.4.5
• grunt-cli 0.1.13
• node.js 0.12.7
• npm 2.11.3

The project was generated using yeoman (1.4.7) but I have the same problem using Karma in a separate project with just jasmine, karma and Grunt (also tested it with Gulp).

I have searched for the warning message but found nothing. I don't know if this is the expected behavior or if there is another way of completing the tasks without warnings.

Answer 1

They changed with new version here:

https://github.com/karma-runner/karma/blob/master/CHANGELOG.md#breaking-changes

var Server = require('karma').Server;
var config = {
    configFile: path.join(__dirname, '/../karma.conf.js'),
    singleRun: singleRun,
    autoWatch: !singleRun
};

var server = new Server(config, done)
server.start()

Answer 2

If you are using the grunt-karma plugin to start the Karma tests from Grunt, you need to update the grunt-karma dependency in your package.json file to 0.12.0:

"devDependencies": {
  ...
  "grunt-karma": "~0.12.0",
  ...
}

Version 0.12.0 of grunt-karma was released earlier today, and it uses the new API: https://github.com/karma-runner/grunt-karma/releases