Is code coverage of performance tests related to source code features? An empirical study on open-source Java systems

Performance testing aims to ensure the operational efficiency of software systems. However, many factors influencing the efficacy and adoption of performance tests in practice are not yet fully understood. For instance, while code coverage is widely regarded as a key quality metric for evaluating the efficacy of functional testing suites, there is limited knowledge about the types and levels of coverage that performance tests specifically achieve. Another important factor, often perceived as a barrier to the broader adoption of performance tests yet remaining relatively unexplored, is their extended execution time. In this paper, we examine (i) the coverage of performance testing suites, (ii) the characteristics of source code associated with performance-tested components, and (iii) the time cost of executing performance tests. Our analysis on open-source Java systems reveals that performance tests achieve significantly lower code coverage than functional tests, as expected, and it highlights a significant trade-off between coverage and execution time. Our results also indicate a lack of generalizable characteristics in the source code covered by performance tests.