LEGenT: Localizing Errors and Generating Testcases for CS1

In a CS1 course, testcases are the most common way of providing feedback. However, manually designed testcases, even if carefully crafted, may miss out on certain crucial corner cases. These testcases are only generated once for the whole class and do not take into account errors generated by specific students. This paper presents LEGenT, an automated tool that generates personalized testcases for student submission. LEGenT first localizes a statement in the program that causes deviation from the expected behaviour. Then it generates testcases that expose the deviation to the student. Our premise is that such a targeted test would help students identify one of the early reasons for the deviation.