Studying Logging Practice in Test Code

Logging is widely used in modern software development to record run-time information for software systems and plays a significant role in software testing. Although the research area of logging has attracted much attention, there is no research on the practice of test logging (i.e., the logging involved in test files). To fill this knowledge gap, we conduct this empirical study to explore and disclose the practice of test logging. This study examines 21 open-source subjects with ∼8 million sources lines of code and ∼70 thousand logging statements. We organize our study by answering four research questions, and as a result, (1) we have yielded five findings to reveal the differences between test and production logging statements, (2) we have disclosed four findings regarding the differences between the maintenance efforts of test and production logging statements, (3) we have identified four reasons why developers use test log and (4) we have uncovered the relationship between test logging and production logging. To the best of our knowledge, this is the first study that quantitatively and qualitatively analyzes the logging practices in test and production code, providing developers and researchers with insight into this topic