How I'm supposed to run unit test for angular ui-router

I'm quite new with karma... I want to contribute with a bug fixing for angular ui-router.

I need to write new unit tests and check all the other tests but I don't understand how I'm supposed to run karma on this project.

I have tried with:

grunt dev

But karma seems to be not running, I get "There is no server listening on port 8080". And in any case also if I manually run karma I see only a summary, the output is something like: "Done with errors".

So I have tried with:

karma start config/karma.js

but I don't see any output result, maybe karma reporters are not configured?

I have also tried with

grunt default

This command seems to do what I need but I should running it every time, it is not configured to autowatch.

On my projects I usually configure karma or mocha to auto watch files and I simply leave it in the background.

How do you suggest to work on ui-router project or other similar project? Maybe I missing something...