One embodiment provides a system for automatic program repair (APR). The system identifies a first set of components under repair in a software system and determines, while executing an original test, second and third sets of components that are executed before and after, respectively, the first set of components. The system generates a first block of mock code that runs faster and simulates runtime behaviors of the second set of components, identifies a code region within the third set of components that affects a test result of the software system, and generates a second block of mock code that runs faster and affects the test result similarly. The system generates a fast-result test by replacing the second set of components with the first block of mock code and replacing the third set of components with the second block of mock code and performs APR by executing the fast-result test.