Wal-Mart Stores is running a new price-comparison test in at least 1,200 U.S. stores and squeezing packaged goods suppliers in a bid to close a pricing gap with German-based discount grocery chain Aldi and other U.S. rivals like Kroger Co, according to four sources familiar with the moves. Wal-Mart launched the price test across 11 Midwest and Southeastern states such as Iowa, Illinois and Florida, focusing on price competition in the grocery business that accounts for 56 percent of the company’s revenue, said vendor sources with direct knowledge of the matter who did not wish to be identified for fear of disrupting business relations with Wal-Mart.