How to check if you use karma js?

Question

how can i check if i am running on karma?

When I'm on Karma, I tried with this,

var path = '';
if (typeof window.karma !== 'undefined') {
  path += 'base/'
} 

alert(typeof window.karma); // undefined

I tried with this,

var path = '';
if (typeof window.__karma__ !== 'undefined') {
  path += 'base/'
} 

alert(typeof window.__karma__); // still undefined

Any ideas?