SafeRevert: When Can Breaking Changes be Automatically Reverted?

When bugs or defects are introduced into a large scale software repository, they reduce productivity. Programmers working on related areas of the code will encounter test failures, compile breakages, or other anomalous behavior. On encountering these issues, they will need to troubleshoot and determine that their changes were not the cause of the error and that another change is at fault. They must then find that change and revert it to return the repository to a healthy state. In the past, our group has identified ways to identify the root cause (or culprit) change that introduced a test failure even when the test is flaky. This paper focuses on a related issue: at what point does the Continuous Integration system have enough evidence to support automatically reverting a change? We will motivate the problem, provide several methods to address it, and empirically evaluate our solution on a large set (25,137) of real-world breaking changes that occurred at Google. SafeRevert improved recall (number of changes recommend for reversion) by 2× over the baseline method while meeting our safety criterion.