How to Enable Image Rollover in Shopify Testament Theme

Image rollover swaps in a second photo when a shopper hovers over a product image — useful for showing an alternate angle or the product in use without a click.

Steps

Make sure the product has at least a second image assigned — rollover needs something to swap to.
In your Shopify admin, go to Online Store > Themes and click Customize on Testament.
Open a collection template and select the Product grid section (or the equivalent image block on the product page).
Find the Image rollover (or similarly named hover) setting and turn it on.
Click Save.

This works well on collection grids for showing a product worn or in use on hover, and on the product page itself as a lighter-weight alternative to opening the full gallery.