Tests for "algorithms" section
Click on each button in sequence from top to bottom without refreshing the page.
Each button will bring up the Payment Request UI window.
User aborts the payment request algorithm
When presented with the payment sheet, abort the payment request (e.g., by hitting the esc key or pressing a UA provided button).
Shipping address changed algorithm
When prompted, please change or enter a new shipping address and then select Pay.
Shipping option changed algorithm
Finally, when prompted, please select "shipping option 2" and then select Pay.
If you find a buggy test, please file a bug
and tag one of the owners.