Angular-cli unit testing do not work

I just build an application with the official angular-cli on ubuntu 14.04 with nam version v2.14.12 and node version v4.2.6 and karma version v0.13.19,

I did steps below:

sudo ng new Project
cd Project
ng serve

The project is working, I have project Works! on localhost:4200

ng build

Built project successfully. Stored in "dist/"

cd dist

I am now in the building project folder

karma start

I just have a confirmation message that says: Karma v0.13.19 server started at http://localhost:9876/

What I did wrong? Why no unit testings appear?

Thanks :)