Ember : addObject/ pushObject is not a function

I recently moved from ember 1.x to 2.6. I am not able to use addObject/ pushObject like i used to. Ember : 2.6.2 jQuery : 2.2.4

import Ember from 'ember';
export default Ember.Controller.extend({
test:['sibi','john'],
init:function() {
this.get('test').pushObject('sebastian');
}
});

This throws an error like pushObject is not a function. What is the workaround? Thank you.