Variations on a Theme: Performance Testing and Functional Unit Testing

The right types of performance tests can reveal functionality problems that would not usually be detected during unit testing. For example, concurrency and thread safety problems can manifest themselves in poor performance or deadlocks, leading to incorrect output. Because unit tests inherently lack concurrent activity, these problems rarely manifest themselves in functional tests. André Bondi describes test structures based on rudimentary models that reveal valuable insights about system scalability, performance, and system function. For example, to ensure that resource utilization increases linearly with the load-a necessary condition for scalability-transactions should be submitted to systems for long periods of time at different rates. Conversely, when the load is constant, performance measures should be constant. Deviations from these expectations are symptomatic of programming or design problems such as software bottlenecks, memory leaks, or system instability due to defects. André illustrates these concepts with example results, shows you how to automate the analysis of performance test results.