Walmart is testing automated grocery fulfillment to add another layer of convenience to its developing e-commerce muscles, deploying an automated kiosk to dispense online grocery orders at one store in Oklahoma.A step beyond the retailer's expanding curbside grocery pickup service, the kiosk can operate unmanned, fulfilling hundreds of orders a day and enabling pickups at any hour. The 20-by-80-foot kiosk — dubbed "24-Hour Pickup" — can hold up to 30,000 products, including frozen and refrigerated items.A video uploaded to the retailer's YouTube channel sums up the service. (See below.)Shoppers provide a confirmation code on a screen to open bay doors that reveal their order. There is no extra cost for the service. Walmart's Asda division operates similar units in the U.K.The mass merchant also is experimenting with an in-store, automated kiosk for picking up online general merchandise orders. Dubbed "Pickup Tower," the kiosk is 16 feet tall by eight feet wide, and can hold some 300 items. It is equipped with a sensor that can tell when someone approaches, opening a door that gives the shopper access to a scanner for a bar code sent to her smartphone that will trigger the release of her order. Following a successful initial test in one location, the pilot has expanded to a handful of others.Both kiosks promise to spit out shopper orders in under 60 seconds.