An artificial intelligence based method for improving a software testing process, according to which upon finding a bug, a set of candidate diagnoses is proposed to the tester, based on a Model-Based Diagnosis (MBD) process. A planning process is used for automatically suggesting further test steps to be performed by the tester, to identify the correct diagnosis for the developer in the form of faulty software component that caused the bug, while minimizing the tests steps performed by the tester. Additional information is provided to the MBD process, based on the outputs of the further test steps, thereby pruning incorrect candidate diagnoses. These steps are iteratively repeated while in each time, minimizing the set of candidate diagnoses, until a single diagnosis remains in the set.