tests: Move part of UCommand::run to a new function
tests: Move part of UCommand::run to a new function

kevgeniy/coreutils,ebfe/coreutils,tempbottle/coreutils,jbcrail/coreutils,uutils/coreutils,Heather/coreutils,Heather/coreutils,keunwoo/coreutils,kwantam/coreutils,Arcterus/coreutils,ebfe/coreutils,Arcterus/coreutils,uutils/coreutils,kwantam/coreutils,jbcrail/coreutils,kevgeniy/coreutils,wimh/coreutils,keunwoo/coreutils,wimh/coreutils,tempbottle/coreutils,uutils/coreutils