There are several techniques available to inject faults. Heavy ion bombarding, laser beams, and pin-level forcing techniques can insert real hardware faults on a system. Other techniques such as Software-Implemented Fault Injection (SWIFI) and Scan Chain based Fault Injected (SCFI) rely on debugging and testing resources of modern chips to emulate faults through the manipulation of the system state, e.g., flipping a bit on a register or corrupting the result of a floating point calculation. Mutation is yet another methodology - here, source code is instrumented to reflect programming mistakes, i.e., bugs.