EmberJS componet unit test fails

I'm trying to unit test an EmberJS component. Specifically, I want to verify that the component loses focus when the tab key is pressed. When I run the test, there is a call to focus the component. Then a trigger event that sends the tab key is sent. At this point, I get an error that the element cannot be found. Any ideas. Here's the code:

it('should behave as expected', function() {
    var component = this.subject();

    this.render();
    expect(component.get('id')).to.equal('textareaId');

    $('#textareaId').focus();
    expect($("#textareaId").is(":focus")).to.equal(true);

    triggerEvent('#textareaId', 'keydown', { keyCode: 9, which: 9 });

    andThen(function(){

      expect($("#textareaId").is(":focus")).to.equal(false);

    });
  });
});