Most home appliance devices such as electric ovens are reactive systems which repeat receiving a user input/event through an event handler, updating their internal state based on the input, and generating outputs. A challenge to test a reactive program is to check if the program correctly reacts to various non-deterministic sequence of events because an unexpected sequence of events may make the system fail due to the race conditions between the main loop and asynchronous event handlers. Thus, it is important to systematically generate/test various sequences of events by controlling the order of events and relative timing of event occurrences with respect to the main loop execution. In this paper, we report our industrial experience to solve the aforementioned problem by developing a systematic event generation framework based on concolic testing technique. We have applied the framework to a LG electric oven and detected several critical bugs including one that makes the oven ignore user inputs due to the illegal state transition.

As web technologies have evolved, the complexity of dynamic web applications has increased significantly and web applications suffer concurrency errors due to unexpected orders of interactions among web browsers, users, the network, and so forth. In this paper, we present WAVE (Web Applications Virtual Environment), a testing framework to detect concurrency errors in client-side web applications written in JavaScript. WAVE generates various sequences of operations as test cases for a web application and executes a sequence of operations by dynamically controlling interactions of a target web application with the execution environment. We demonstrate that WAVE is effective and efficient for detecting concurrency errors through experiments on eight examples and five non-trivial real-world web applications.