Question $\backslash$#$3-$ Usability Testing

You are a software developer on a software development team that is gathering requirements for the Shopizer e$-$commerce web application. Your manager sends you the below e$-$mail:

"All stakeholders agree that it's critically important that Shopizer users trust the checkout feature of the application. We can test that the feature checks customers out correctly, but how can we possibly test that users trust the feature? Do you have any ideas?"

Write a reply to your manager. Suggest a specific requirement to capture this stakeholder need, along with a suggested approach to verify the requirement has been met when the completed system is built $($including a specific artifact of some kind used as part of this verification approach$).$