Deterministically Testing Actor-Based Concurrent Software

Non-deterministic concurrent behavior of software prohibits the idempotent property of tests. XUnit frameworks traditionally do not offer support to deal with these concurrency issues which reduces the significance of unit testing concurrent software. In this paper we propose a tool which supports deterministic testing of concurrent software based on the Actor model. This tool reveals race conditions and seamlessly integrates with xUnit-like frameworks. In our approach, a Coloured Petri Net model is constructed per test as well as the code under test. This model allows isolation of concurrent behavior from the effective actor state. Subsequently, the state space is calculated and traces covering all states are constructed. Corresponding with these traces our tool issues test runs, guaranteeing full state space coverage of each test. Moreover, each failed trace can be backtracked, revealing valuable information concerning the race condition.