Large-scale Android apps that provide complex functions are gradually becoming the mainstream in Android app markets. They tend to display many GUI widgets on a single GUI page, which, unfortunately, can cause more redundant test actions—actions with similar functions—to automatic testing approaches. The effectiveness of existing testing approaches is still limited, suggesting the necessity of reducing the test effort on redundant actions. In this article, we first identify three types of GUI structures that can cause redundant actions and then propose a novel approach, called action equivalence evaluation, to find the actions with similar functions by exploiting both GUI structure and functionality. By integrating this approach with existing testing tools, the test efficacy can be improved. We conducted experiments on 17 large-scale Android apps, including three industrial apps Google News , Messenger , and WeChat . The results show that more instructions can be covered, and more crashes can be detected, compared to the state-of-the-art Android testing tools. Twenty-nine real bugs were found in our experiment, and moreover, 760 bugs over 40 versions of WeChat had been detected in the real test environment during a 3-month testing period.

Attracting over one billion registered users globally, WeChat’s mini-game platform has become one of the largest gaming platforms with hundreds of thousands of published mini-games. To ensure the quality of experiences across a massive number of mini-games, automated UI testing has become essential for WeChat. However, sliding-gesture-induced exploration tarpits, states where a testing tool becomes trapped in repetitive, unsuccessful gesture attempts, cause the testing tool to waste up to 98% of its testing budget due to its inability to execute proper sliding gestures. While mini-games typically contain visual hints (e.g., sliding indicators) guiding the desired sliding gestures, exploiting these hints to escape exploration tarpits faces two major challenges in industrial settings: (1) robustness challenge when exploiting hints from only several discontinuous screenshots, and (2) efficiency challenge to support thousands of concurrent testing services with minimal overhead and costs.To address the preceding challenges, we report our experiences in developing and deploying SlideScout, a three-stage approach for detecting and escaping sliding-gesture-induced exploration tarpits via efficient exploitation of visual hints. First, SlideScout concurrently monitors the testing progress and detects sliding indicators alongside screenshot collection, improving efficiency by reusing preprocessed results in subsequent stages. Second, SlideScout reconstructs potential sliding trajectories using multiple heuristics, addressing robustness challenges when precise trajectories are unavailable due to discontinuous screenshots. Third, SlideScout applies the inferred sliding gestures until it successfully escapes the tarpit, enabling easy integration with existing testing tools. Deployed at WeChat internally for six months, SlideScout has helped reveal 25,000 crashes and 120,000 JavaScript errors, detecting 50% more crashes compared to the pre-deployment baseline within the same time period. We summarize three major lessons learned from developing and deploying SlideScout.

The explosive growth of mini-game platforms has led to widespread code plagiarism, where malicious users access popular games’ source code and republish them with modifications. While existing static analysis tools can detect simple obfuscation techniques like variable renaming and dead code injection, they fail against sophisticated deep obfuscation methods such as encrypted code with local or cloud-based decryption keys that completely destroy code structure and render traditional Abstract Syntax Tree analysis ineffective. To address these challenges, we present JSidentify-V2, a novel dynamic analysis framework that detects mini-game plagiarism by capturing memory invariants during program execution. Our key insight is that while obfuscation can severely distort static code characteristics, runtime memory behavior patterns remain relatively stable. JSidentify-V2 employs a four-stage pipeline: (1) static pre-analysis and instrumentation to identify potential memory invariants, (2) adaptive hot object slicing to maximize execution coverage of critical code segments, (3) Memory Dependency Graph construction to represent behavioral fingerprints resilient to obfuscation, and (4) graph-based similarity analysis for plagiarism detection.We evaluate JSidentify-V2 against eight obfuscation methods on a comprehensive dataset of 1,200 mini-games. Our framework achieves over 90% similarity detection across all tested obfuscation techniques, maintaining high accuracy even against advanced decryption-based methods where existing tools achieve near 0% detection rates. In real-world deployment, JSidentify-V2 achieves 100% precision and 99.8% recall while delivering an 8× speedup compared to previous methods. Our production deployment demonstrates that plagiarism complaints have decreased by over 80%, proving JSidentify-V2’s effectiveness in protecting intellectual property rights in mini-game ecosystems.

User Interface (UI) testing is crucial for quality assurance of industrial mobile applications, and yet it remains labor-intensive and challenging to automate effectively. Recent advances in Vision-Language Models (VLMs) present a promising solution for automating GUI testing by mapping natural language instructions to pixel-level actions, significantly reducing the manual effort required for writing test scripts and even designing test cases. While numerous VLMs have been proposed and evaluated for GUI testing, they often fail to meet two critical industrial requirements: (1) effectiveness when handling complex, multi-step workflows in industrial applications, and (2) efficiency for large-scale, high-frequency testing environments typical in industrial settings. Toward addressing the preceding industrial requirements, in this paper, we report our experiences in developing and deploying RePeek, a novel approach employing a unified three-stage pipeline for both training and inference, enables a VLM to explicitly detect and reason over discrete GUI elements, thereby overcoming the limitations of pixel-based reasoning for both efficiency and effectiveness improvements. In the first stage, RePeek integrates a lightweight UI-element detector named OmniParser to decompose UI screenshots into a structured element list. In the second stage, RePeek adopts the vision encoder of the VLM to generate the embedding for each element. In the third stage, RePeek fuses these element embeddings with the textual instruction to reason and perform classification directly on the UI elements, empowering efficient small models to achieve superior performance against expensive large models. Comprehensive evaluations on public benchmarks and deployment at WeChat show that RePeek consistently achieves superior accuracy and efficiency compared to state-of-the-art VLMs. Specifically, RePeek enables a fine-tuned Qwen2.5-VL-3B model to outperform a 72B model with 75% less training data, validating the effectiveness of incorporating domain knowledge into VLM-based GUI testing. We conclude by summarizing three key lessons from developing and deploying RePeek, offering insights for both researchers and practitioners working on industrial-strength UI testing.

UI automation tests play a crucial role in ensuring the quality of mobile applications. Despite the growing popularity of machine learning techniques to generate these tests, they still face several challenges, such as the mismatch of UI elements. The recent advances in Large Language Models (LLMs) have addressed these issues by leveraging their semantic understanding capabilities. However, a significant gap remains in applying these models to industrial-level app testing, particularly in terms of cost optimization and knowledge limitation. To address this, we introduce CAT to create cost-effective UI automation tests for industry apps by combining machine learning and LLMs with best practices. Given the task description, CAT employs Retrieval Augmented Generation (RAG) to source examples of industrial app usage as the few-shot learning context, assisting LLMs in generating the specific sequence of actions. CAT then employs machine learning techniques, with LLMs serving as a complementary optimizer, to map the target element on the UI screen. Our evaluations on the WeChat testing dataset demonstrate the CAT's performance and cost-effectiveness, achieving 90% UI automation with $0.34 cost, outperforming the state-of-the-art. We have also integrated our approach into the real-world WeChat testing platform, demonstrating its usefulness in detecting 141 bugs and enhancing the developers' testing process.

WeChat, a widely-used messenger app boasting over 1 billion monthly active users, requires effective app quality assurance for its complex features. Record-and-replay tools are crucial in achieving this goal. Despite the extensive development of these tools, the impact of waiting time between replay events has been largely overlooked. On one hand, a long waiting time for executing replay events on fully-rendered GUIs slows down the process. On the other hand, a short waiting time can lead to events executing on partially-rendered GUIs, negatively affecting replay effectiveness. An optimal waiting time should strike a balance between effectiveness and efficiency. We introduce WeReplay, a lightweight image-based approach that dynamically adjusts inter-event time based on the GUI rendering state. Given the real-time streaming on the GUI, WeReplay employs a deep learning model to infer the rendering state and synchronize with the replaying tool, scheduling the next event when the GUI is fully rendered. Our evaluation shows that our model achieves 92.1% precision and 93.3% recall in discerning GUI rendering states in the WeChat app. Through assessing the performance in replaying 23 common WeChat usage scenarios, WeReplay successfully replays all scenarios on the same and different devices more efficiently than the state-of-the-practice baselines.

Mobile games play an increasingly important role in our daily life. The quality of mobile games can substantially affect the user experience and game revenue. Different from traditional mobile games, the mini-games provided by our partner, Tencent, are embedded in the mobile app WeChat, so users do not need to install specific game apps and can directly play the games in the app. Due to the convenient installation, WeChat has attracted large numbers of developers to design and publish on the mini-game platform in the app. Until now, the platform has more than one hundred thousand published mini-games. Manually testing all the mini-games requires enormous effort and is impractical. There exist automated game testing methods; however, they are difficult to be applied for testing mini-games for the following reasons: 1) Effective game testing heavily relies on prior knowledge about game operations and extraction of GUI widget trees. However, this knowledge is specific and not always applicable when testing a large number of mini-games with complex game engines (e.g., Unity). 2) The highly diverse GUI widget design of mini-games deviates significantly from that of mobile apps. Such issue prevents the existing image-based GUI widget detection techniques from effectively detecting widgets in mini-games.

Large-scale online systems are complex, fast-evolving, and hardly bug-free despite the testing efforts. Backend system monitoring cannot detect many types of issues, such as UI related bugs, bugs with small impact on backend system indicators, or errors from third-party co-operating systems, etc. However, users are good informers of such issues: They will provide their feedback for any types of issues. This experience paper discusses our design of iFeedback, a tool to perform real-time issue detection based on user feedback texts. Unlike traditional approaches that analyze user feedback with computation-intensive natural language processing algorithms, iFeedback is focusing on fast issue detection, which can serve as a system life-condition monitor. In particular, iFeedback extracts word combination-based indicators from feedback texts. This allows iFeedback to perform fast system anomaly detection with sophisticated machine learning algorithms. iFeedback then further summarizes the texts with an aim to effectively present the anomaly to the developers for root cause analysis. We present our representative experiences in successfully applying iFeedback in tens of large-scale production online service systems in ten months.

Content caching is a promising approach in edge computing to cope with the explosive growth of mobile data on 5G networks, where contents are typically placed on local caches for fast and repetitive data access. Due to the capacity limit of caches, it is essential to predict the popularity of files and cache those popular ones. However, the fluctuated popularity of files makes the prediction a highly challenging task. To tackle this challenge, many recent works propose learning based approaches which gather the users' data centrally for training, but they bring a significant issue: users may not trust the central server and thus hesitate to upload their private data. In order to address this issue, we propose a Federated learning based Proactive Content Caching (FPCC) scheme, which does not require to gather users' data centrally for training. The FPCC is based on a hierarchical architecture in which the server aggregates the users' updates using federated averaging, and each user performs training on its local data using hybrid filtering on stacked autoencoders. The experimental results demonstrate that, without gathering user's private data, our scheme still outperforms other learning-based caching algorithms such as m-epsilon-greedy and Thompson sampling in terms of cache efficiency.