How to test IonSlides

I am trying to test IonSlides in an Angular component using methods like getActiveIndex().

Is there a way to mock IonSlides?

I have something like :
@ViewChild('mySlider') mySlider: IonSlides;

in my component.

this.mySlider is always undefined obviously. How can I mock it?

I am using a standard Angular project with Jasmine.