set CSS class depending on returned string with Ember

Im still learning ember and i didn't got how i can apply certain CSS class depending on the returned string of a model on a certain controller.

The official documentation (http://ift.tt/1CgFtup) only covers when you have a boolean.

I didn't manage to apply this knowledge for my case. I have status string string like : "passed", "failed", "pendent" and "blocked", which i want to apply different css class for each status.

Any examples on how to achieve that?