The Laotian central bank’s test of its digital currency will involve consumers using the currency to pay for purchases at stores. (Photo obtained by Nikkei)KEITA SEKIGUCHI, Nikkei fintech editor | TOKYO — The Laotian central bank tests its digital currency starting Tuesday in cooperation with a Japanese blockchain developer, part of a growing interest in the currency among Asia’s monetary authorities.Bank of the Lao PDR and Tokyo-based Soramitsu signed a memorandum of understanding Monday to begin a proof of concept.