A blowout-preventer-stack one-trip test tool , comprising: a solid test pin having a primary connector surface at a medial location and a secondary connector surface at a top location; a running tool adapted to removably couple, release, and re-couple, at a bottom location, with said solid test pin at said primary connector surface ; a centralizer mounted around a portion of said running tool , where said centralizer maintains said running tool in the center of the blowout preventer stack; a drill-pipe connector at a top location of said running tool , having standard drill-pipe threads and adapted to operate with standard drill pipe ; wherein said solid test pin is adapted to securely removably attach at a bottom location to a standard test plug by standard drill-pipe threads ; wherein said running tool is adapted to attach to standard drill pipe at said drill-pipe connector , by standard drill-pipe threads , for lowering to the wellhead, testing, and retrieval; wherein said secondary connector surface is adapted to attach to standard drill pipe by standard drill-pipe threads ; wherein said running tool is adapted to uncouple with said solid test pin , at the wellhead, in order to allow for partial withdrawal of the running tool and the drill string above for testing of blind and shear rams without damaging drill pipe, and to subsequently securely re-couple with said solid test pin for withdrawal of said test tool at completion of testing; and wherein said secondary connector surface having standard drill-pipe threads accommodates retrieval and withdrawal of said solid test pin attached to the standard test plug using an emergency retrieval tool . a solid test pin having a primary connector surface at a medial location and a secondary connector surface at a top location; a running tool adapted to removably couple, release, and re-couple, at a bottom location, with said solid test pin at said primary connector surface ; a centralizer mounted around a portion of said running tool , where said centralizer maintains said running tool in the center of the blowout preventer stack; a drill-pipe connector at a top location of said running tool , having standard drill-pipe threads and adapted to operate with standard drill pipe ; wherein said solid test pin is adapted to securely removably attach at a bottom location to a standard test plug by standard drill-pipe threads ; wherein said running tool is adapted to attach to standard drill pipe at said drill-pipe connector , by standard drill-pipe threads , for lowering to the wellhead, testing, and retrieval; wherein said secondary connector surface is adapted to attach to standard drill pipe by standard drill-pipe threads ; wherein said running tool is adapted to uncouple with said solid test pin , at the wellhead, in order to allow for partial withdrawal of the running tool and the drill string above for testing of blind and shear rams without damaging drill pipe, and to subsequently securely re-couple with said solid test pin for withdrawal of said test tool at completion of testing; and wherein said secondary connector surface having standard drill-pipe threads accommodates retrieval and withdrawal of said solid test pin attached to the standard test plug using an emergency retrieval tool . <EOS>