Focus that you are willing to learn the skill if they are willing to train. I would suggest to review the positions job description instead of just assuming you know what they are going to ask. They are looking mainly for familiarity. As a testing technician your main job is to learn and adapt to current technology they do not expect you to just jump into a position and do well right away. Become familiar and study what you are doing manuals will help you explain what you are doing.