Embodiments of the present disclosure provide techniques and configurations for a package testing system. In some embodiments, the system may comprise a printed circuit board (PCB), including one or more sensors disposed adjacent to a corner of the PCB to face a package to be tested, to detect an electrical edge of the package. The PCB may include a contactor array disposed to face respective interconnects of the package. The system may further include a controller coupled with the one or more sensors, to process an input from the one or more sensors, to identify the electrical edge of the package, and initiate an adjustment of a position of the PCB relative to the package, based at least in part on the electrical edge of the package, to substantially align contacts of the contactor array with the respective interconnects of the package. Other embodiments may be described and/or claimed.