Attribution of Work in Programming Teams with Git Reporter

Many courses in computer science feature team projects which expose students to challenges resembling those in the software industry. For a fair assessment in team projects, measuring each student's contribution is a prerequisite. As version control systems store snapshots of a team's work, they can help make students' contributions transparent. However, available tools do not offer the required functionality to effectively analyze the distribution of work in a group. In this paper, we introduce Git Reporter, a new tool for measuring contributions in projects based on Git, the most widely used version control system. Git Reporter categorizes students' contributions based on importance and summarizes the distribution of work. Moreover, our tool provides a detailed mapping from each part of the project to its respective author. We found that using Git Reporter helps teaching assistants evaluate the quality of students' contributions. Furthermore, it significantly increases teaching assistants' confidence in their grading decision when compared with Git or a popular tool based on Git. A survey conducted among students indicates that Git Reporter may raise group awareness in student teams and help them divide the work more equally. Git Reporter is available as an open-source tool supporting assessment and team work. Furthermore, Git Reporter can support research in computing education and software repository mining by providing improved metrics compared to existing tools.