Core answer
Start here. This is the direct spoken answer to practice first.
Overview
Accessibility testing must prove interaction and focus behavior, not only the presence of ARIA attributes.
I start with semantic HTML and query controls by role, label, or visible name so the test fails when the accessible contract disappears. I exercise keyboard actions such as Tab, Enter, Escape, and arrow keys according to the widget pattern, then verify focus and the visible outcome. Automated accessibility checks catch common violations but do not replace behavior tests or manual review.