In one embodiment, a computer program product for injecting error code includes a computer readable storage medium having computer readable program code embodied therewith. The computer readable program code includes computer readable program code configured to determine critical points in executing code of software under test, computer readable program code configured to determine an appropriate response action for each critical point based on an error encountered at each critical point, computer readable program code configured to inject a critical point segment into the executing code at a corresponding critical point, and computer readable program code configured to output a unique identifier of each critical point segment. In another embodiment, a system includes a processor, and a computer readable storage medium having computer readable program code embodied therewith having the above described functionality. Other systems and computer program products are described according to more embodiments.