A specification-based unit test generation paradigm that replaces the code under test in the prompt with an LLM-generated specification docstring is introduced, showing that this paradigm effectively reduces misguided tests while substantially increasing effective tests, improves multi-round, feedback-driven test generation pipelines, and remains applicable to both buggy and bug-free code.
Abstract
While Large Language Models (LLMs) show great promise for automating unit test generation, recent studies suggest that the quality of generated tests can be negatively impacted when models are prompted with buggy code. This paper presents a new metric to quantitatively measure the"misguidance effect,"a phenomenon where buggy code steers LLMs toward generating tests that validate its erroneous behavior rather than expose it. Our analysis reveals that prompting LLMs with buggy code has a severe, twofold impact: it significantly increases"misguided tests"that assert incorrect behavior while simultaneously suppressing the generation of effective, bug-finding tests. We further corroborate this effect from a model-internal perspective, showing that buggy code skews LLMs'preference toward tests that assert the same erroneous behavior. To counter this, we introduce and validate a specification-based unit test generation paradigm that replaces the code under test in the prompt with an LLM-generated specification docstring. Our results show that this paradigm effectively reduces misguided tests while substantially increasing effective tests, improves multi-round, feedback-driven test generation pipelines, and remains applicable to both buggy and bug-free code. Overall, these results suggest that specification-based prompting is a promising strategy for mitigating misguidance from buggy code in LLM-generated unit tests.
This paper presents a formal mathematical model for categorizing the outcome of generated-tests into four classes, a couple of basic metrics: Bug-Revealing Rate (BRR) and Bug-Validating Rate (BVR); and two basic statistical tests to ensure that the results are rigorous.
Zeyad Farooq Lutfi· Al-Noor Journal of Engineeri...· 0 citations
An empirical study involving 5 Large Language Models and 4 benchmarks evaluates the effectiveness and efficiency of 3 widely used adequacy criteria: statement coverage, branch coverage, and mutation testing, finding that mutation testing only marginally outperforms traditional coverage criteria in both triggering and detecting faults.
Asma Hamidi, Michael Konstantinou, R. Degiovanni et al.· 0 citations
This work presents CodeMechanic, a bug-property-guided system for generating constrained mit- igations for spatial memory corruption that combines a two-dimensional static and dynamic context extractor with in-prompt debugging knowledge and stepwise val- idation to limit the effect of LLM errors.
Han Zheng, Rafaila Galanopoulou, Ilia Shumailov et al.· 0 citations
Code translation, as a challenging and fundamental task, is increasingly relying on large language models (LLMs). However, LLMs often give seemingly plausible but fallacious translations, misleading and even deceptive to debugging developers. We propose tHinter, an automated approach that frames translation error localization as a differential testing task. By fuzzing and a novel Bayesian-inspired algorithm that integrates developer heuristics into SBFL, tHinter thoroughly exposes translation errors and effectively pinpoints functionality-twisting errors. We evaluate tHinter in a Python to C++ scenario, a representative and challenging task for migrating high-level logic to performance-critical systems. Experiments show that tHinter achieves the highest F1 in localizing translation errors, outperforming all baselines. When debugging LLM-translated code with human efforts, it averagely reduces 71% lines developers need to review. Furthermore, we provide a comprehensive evaluation reference beyond traditional fault localization metrics. We integrate mixed-factorial user studies, expert validation, and SWOT-based strategic analysis to assess the perceived helpfulness and resilience within the rapidly evolving LLM landscape, offering a methodologically rigorous example for researchers in the context of AI-augmented software engineering.
Shengnan Wu, Xin-Yu Sun, Xin Wang et al.· ACM Transactions on Software...· 0 citations
Large language models (LLMs) have become ubiquitous in software development, with LLM-based automated program repair tools increasingly used during code review. In this report, we explore the iterative blind use of LLMs as bug-fixers. Across multiple models and repair environments, we find that LLMs consistently claim to detect bugs in entirely bug-free programs while the rate of repair of buggy programs is less than that of the damage to correct programs. We also explore the long-term dynamics of this iterative process, and find that this frequently reaches a pseudo-bug-fixing cycle where the same changes are added and removed again ad infinitum. Lastly, via mechanistic probing, we unveil the existence of a steering vector which controls the editing propensity, suggesting that LLMs have an internal representation of ``buggy code", and that this representation is what is falsely activated to induce pseudo-bug fixing. These results provide insight towards the dynamics of fully autonomous bug-fixing systems, as well as stopping conditions under ambiguous goals.
Xietao Wang-Lin, Anton Isopoussu, Louis Mahon· 0 citations
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