Angular data-binding after setting input value with karma

Angular data-binding after setting input value with karma

My question is extremely close to that one :
Update Angular model after setting input value with jQuery
But, here, my input is modified by the val() method of Karma runner :
element('#stuff_input').val('theNewValForStuff');
I won't detail my test here, it would be irrelevant. But you will easily
guess that the test will fail if binding is not properly maintained.
In production, #stuff_input is actually modified with the keyboard by
user, never with any jQuery method of course. So I don't want to use
$watch, I don't want to introduce any more complexity into my production
code just because :
1) Karma do not allow keyboard input natively
2) Karma event do not maintain data-binding with val()
Any idea of how to solve this ?
Thanks