Why Students Write Low-Quality Unit Testing Scripts: An Empirical Study from Software Testing Skill Competitions

We conducted an empirical study on 440 JUnit unit testing scripts collected from the Software Testing Skill Competitions. Findings reveal that: 1) The polarization of unit testing skills is severe. 2) The scores of the testing missions that provide the program flowchart are higher than others. In comparison, the scores of the testing missions that only provide textual descriptions of the program under are lower. 3) Test oracles are sometimes not taken seriously, resulting in the incorrect expected output. 4) Students usually perform better on testing missions of statement coverage and branch coverage but worse on the testing mission of condition coverage. The above findings may provide helpful suggestions for teachers in the education of unit testing.