Software history under the lens: A study on why and how developers examine it

Despite software history being indispensable for developers, there is little empirical knowledge about how they examine software history. Without such knowledge, researchers and tool builders are in danger of making wrong assumptions and building inadequate tools. In this paper we present an in-depth empirical study about the motivations developers have for examining software history, the strategies they use, and the challenges they encounter. To learn these, we interviewed 14 experienced developers from industry, and then extended our findings by surveying 217 developers. We found that history does not begin with the latest commit but with uncommitted changes. Moreover, we found that developers had different motivations for examining recent and old history. Based on these findings we propose 3-LENS HISTORY, a novel unified model for reasoning about software history.