Angular2 Component: Testing form input value change
It might be a little bit late, but it seems that your code is not dispatching input event after setting input element value:
// ... input.value = 'fake-search-query';input.dispatchEvent(new Event('input'));cmpFixture.detectChanges();// ...
Triggering the value change of FormControl is as simple as:
cmpFixture.debugElement.componentInstance.searchInput.setValue(newValue);
Custom component with @input, subscriptions, two way data binding
If you got a custom component you would need further changes in your application to be able to successfully unit test your application
have a look at the gist here this will give you some ideahttps://gist.github.com/AikoPath/050ad0ffb91d628d4b10ef81736af386/raw/846c7bcfc54be8cce78eba8d12015bf749b91eee/@ViewChild(ComponentUnderTestComponent).js
More over complete reading over here carefully otherwise you can easily get confused again -https://betterprogramming.pub/testing-angular-components-with-input-3bd6c07cfaf6