With the advent of multicore processors, there is a trend towards multithreading to take advantage of parallel computing resources. Due to greatly increased complexity, programmers need effective testing methodology that can thoroughly test multithreaded programs. There has been significant progress based on symbolic execution that attempts to exhaustively explore all the intra-thread paths and inter-thread interleavings. However, such testing approach faces two insuperable challenges. Firstly, exploring an astronomically large number of paths and interleavings limits its scalability. Secondly, a path itself does not directly help programmers understand program behavior. In this paper, we propose an alternate testing methodology that focuses on definition-use data flow instead of paths/interleavings. Such approach not only leads to orders of magnitude reduction in testing complexity, but also gives programmers direct help on examining the shared variable usage in a multithreaded program.

GUIs are event-driven applications where the flow of the program is determined by user actions such as mouse clicks and key presses. GUI testing is a challenging task not only because of the combinatorial explosion in the number of event sequences, but also because of the difficulty to cover the large number of data values. We propose GUICat, the first cloud based GUI testing framework that simultaneously generates event sequences and data values. It is a white-box GUI testing tool that augments traditional sequence generation techniques with concolic execution. We also propose a cloudbased parallel algorithm for mitigating both event sequence explosion and data value explosion, by distributing the concolic execution tasks over public clouds such as Amazon EC2. We have evaluated the tool on standard GUI testing benchmarks and showed that GUICat significantly outperforms state-of-the-art GUI testing tools. The video demo URL is https://youtu.be/rfnnQOmZqj4.