Assumptions in OSS Development: An Exploratory Study through the Hibernate Developer Mailing List

Developers constantly make various assumptions regarding requirements, environment, design decisions, etc. during software development. However, these assumptions are usually implicit and undocumented and there is a lack of understanding regarding what assumptions have been made and discussed in software development. Open Source Software (OSS) is recently becoming an important part of software industry. To this end, we conducted an exploratory study on assumptions in OSS development. We extracted and analyzed 9006 posts from the developer mailing list of Hibernate (a popular OSS project), in order to explore (1) assumption expression and (2) classification, (3) the trend of assumptions over time, and (4) related software artifacts of assumptions in OSS development. We identified 832 assumptions from the Hibernate developer mailing list. The findings are: (1) most of the assumptions are expressed as "Feature Request" and "Solution Proposal"; (2) more than half of the identified assumptions are design assumptions and are made for software design; (3) assumptions exist in the whole OSS development lifecycle; and (4) the major category of related artifacts of assumptions is "Design Document".