Boosting the Revealing of Detected Violations in Deep Learning Testing: A Diversity-Guided Method

Due to the ability to bypass the oracle problem, Metamorphic Testing (MT) has been a popular technique to test deep learning (DL) software. However, no work has taken notice of the prioritization for Metamorphic test case Pairs (MPs), which is quite essential and beneficial to the effectiveness of MT in DL testing. When the fault-sensitive MPs apt to trigger violations and expose defects are not prioritized, the revealing of some detected violations can be greatly delayed or even missed to conceal critical defects. In this paper, we propose the first method to prioritize the MPs for DL software, so as to boost the revealing of detected violations in DL testing. Specifically, we devise a new type of metric to measure the execution diversity of DL software on MPs based on the distribution discrepancy of the neuron outputs. The fault-sensitive MPs are next prioritized based on the devised diversity metric. Comprehensive evaluation results show that the proposed prioritization method and diversity metric can effectively prioritize the fault-sensitive MPs, boost the revealing of detected violations, and even facilitate the selection and design of the effective Metamorphic Relations for the image classification DL software.