We present DESIGNATOR, a toolset for generating datasets for testing and retraining deep neural networks (DNNs) performing computer vision tasks in Martian-like environments. The toolset integrates Marsim, a simulator of the Mars environment, and DESIGNATE, a search-based approach combining simulation, generative adversarial networks (GANs), and search-based test input generation. The tool enables users to select a search strategy, launch simulations in MarsSim, and observe the evolution of simulated images, corresponding realistic images, ground truth labels, model predictions, and fitness values. Beyond supporting researchers and practitioners in generating datasets capable of identifying failures and retraining DNNs, DESIGNATOR can be used as a didactic tool to explain how image datasets can be generated using meta-heuristic search. Furthermore, MarsSim can be used standalone, through its API and GUI. MarsSim enables researchers to assess search-based approaches beyond the predominantly studied automotive context. A demo video of DESIGNATOR is available at https: //youtu.be/fGxgpgViPEo.

Software-defined systems revolutionized the management of hardware devices but introduced quality assurance challenges that remain to be tackled. For example, software defined networks (SDNs) became a key technology for the prompt reconfigurations of network services in many sectors including telecommunications, data centers, financial services, cloud providers, and manufacturing industry. Unfortunately, reconfigurations may lead to mistakes that compromise the dependability of the provided services. In this article, we focus on the reconfigurations of network services in the satellite communication sector, and target security requirements, which are often hard to verify; for example, although connectivity may function properly, confidentiality may be broken by packets forwarded to a wrong destination. We propose an approach for FIeld-based Security Testing of SDN Configurations Updates (FISTS). First, it probes the network before and after configuration updates. Then, using the collected data, it relies on unsupervised machine learning algorithms to prioritize the inspection of suspicious node responses, after identifying the network nodes that likely match across the two configurations. Our empirical evaluation has been conducted with network data from simulated and real SDN configuration updates for our industry partner, a world-leading satellite operator. Our results show that, when combined with K-Nearest Neighbor, FISTS leads to best results (up to 0.95 precision and 1.00 recall). Further, we demonstrated its scalability.

In safety-critical systems (e.g., autonomous vehicles and robots), Deep Neural Networks (DNNs) are becoming a key component for computer vision tasks, particularly semantic segmentation. Further, since DNN behavior cannot be assessed through code inspection and analysis, test automation has become an essential activity to gain confidence in the reliability of DNNs. Unfortunately, state-of-the-art automated testing solutions largely rely on simulators, whose fidelity is always imperfect, thus affecting the validity of test results. To address such limitations, we propose to combine meta-heuristic search, used to explore the input space using simulators, with Generative Adversarial Networks (GANs), to transform the data generated by simulators into realistic input images. Such images can be used both to assess the DNN accuracy and to retrain the DNN more effectively. We applied our approach to a state-of-the-art DNN performing semantic segmentation, in two different case studies, and demonstrated that it outperforms a state-of-the-art GAN-based testing solution and several other baselines. Specifically, it leads to the largest number of diverse images leading to the worst DNN accuracy. Further, the images generated with our approach, lead to the highest improvement in DNN accuracy when used for retraining. In conclusion, we suggest to always integrate a trained GAN to transform test inputs when performing search-driven, simulator-based testing.

Mutation testing consists of generating test cases that detect faults injected into software (generating mutants) which its original test suite could not. By running such an augmented set of test cases, it may discover actual faults that may have gone unnoticed with the original test suite. It is thus a desired practice for embedded software running in safety-critical cyber-physical systems (CPS). Unfortunately, the state-of-the-art tool targeting C, a typical language for CPS software, relies on symbolic execution, whose limitations often prevent its application. MOTIF overcomes such limitations by leveraging grey-box fuzzing tools to generate unit test cases in C that detect injected faults in mutants. Indeed, fuzzing tools automatically generate inputs by exercising the compiled version of the software under test guided by coverage feedback, thus overcoming the limitations of symbolic execution. Our empirical assessment has shown that it detects more faults than symbolic execution (i.e., up to 47 percentage points), when the latter is applicable.

The adoption of deep neural networks (DNNs) in safety-critical contexts is often prevented by the lack of effective means to explain their results, especially when they are erroneous. In our previous work, we proposed a white-box approach (HUDD) and a black-box approach (SAFE) to automatically characterize DNN failures. They both identify clusters of similar images from a potentially large set of images leading to DNN failures. However, the analysis pipelines for HUDD and SAFE were instantiated in specific ways according to common practices, deferring the analysis of other pipelines to future work. In this article, we report on an empirical evaluation of 99 different pipelines for root cause analysis of DNN failures. They combine transfer learning, autoencoders, heatmaps of neuron relevance, dimensionality reduction techniques, and different clustering algorithms. Our results show that the best pipeline combines transfer learning, DBSCAN, and UMAP. It leads to clusters almost exclusively capturing images of the same failure scenario, thus facilitating root cause analysis. Further, it generates distinct clusters for each root cause of failure, thus enabling engineers to detect all the unsafe scenarios. Interestingly, these results hold even for failure scenarios that are only observed in a small percentage of the failing images.

Although App updates are frequent and software engineers would like to verify updated features only, automated testing techniques verify entire Apps and are thus wasting resources. We present Continuous Adaptation of Learned Models (CALM) , an automated App testing approach that efficiently test App updates by adapting App models learned when automatically testing previous App versions. CALM focuses on functional testing. Since functional correctness can be mainly verified through the visual inspection of App screens, CALM minimizes the number of App screens to be visualized by software testers while maximizing the percentage of updated methods and instructions exercised. Our empirical evaluation shows that CALM exercises a significantly higher proportion of updated methods and instructions than six state-of-the-art approaches, for the same maximum number of App screens to be visually inspected. Further, in common update scenarios, where only a small fraction of methods are updated, CALM is even quicker to outperform all competing approaches in a more significant way.

Although the security testing of Web systems can be automated by generating crafted inputs, solutions to automate the test oracle, i.e., vulnerability detection, remain difficult to apply in practice. Specifically, though previous work has demonstrated the potential of metamorphic testing—security failures can be determined by metamorphic relations that turn valid inputs into malicious inputs—metamorphic relations are typically executed on a large set of inputs, which is time-consuming and thus makes metamorphic testing impractical. We propose AIM, an approach that automatically selects inputs to reduce testing costs while preserving vulnerability detection capabilities. AIM includes a clustering-based black-box approach, to identify similar inputs based on their security properties. It also relies on a novel genetic algorithm to efficiently select diverse inputs while minimizing their total cost. Further, it contains a problem-reduction component to reduce the search space and speed up the minimization process. We evaluated the effectiveness of AIM on two well-known Web systems, Jenkins and Joomla, with documented vulnerabilities. We compared AIM's results with four baselines involving standard search approaches. Overall, AIM reduced metamorphic testing time by 84% for Jenkins and 82% for Joomla, while preserving the same level of vulnerability detection. Furthermore, AIM significantly outperformed all the considered baselines regarding vulnerability coverage.

Mutation testing can help reduce the risks of releasing faulty software. For such reason, it is a desired practice for the development of embedded software running in safety-critical cyber-physical systems (CPS). Unfortunately, state-of-the-art test data generation techniques for mutation testing of C and C++ software, two typical languages for CPS software, rely on symbolic execution, whose limitations often prevent its application (e.g., it cannot test black-box components). We propose a mutation testing approach that leverages fuzz testing, which has proved effective with C and C++ software. Fuzz testing automatically generates diverse test inputs that exercise program branches in a varied number of ways and, therefore, exercise statements in different program states, thus maximizing the likelihood of killing mutants, our objective. We performed an empirical assessment of our approach with software components used in satellite systems currently in orbit. Our empirical evaluation shows that mutation testing based on fuzz testing kills a significantly higher proportion of live mutants than symbolic execution (i.e., up to an additional 47 percentage points). Further, when symbolic execution cannot be applied, fuzz testing provides significant benefits (i.e., up to 41% mutants killed). Our study is the first one comparing fuzz testing and symbolic execution for mutation testing; our results provide guidance towards the development of fuzz testing tools dedicated to mutation testing.

Abstract Edge computing is a distributed computing paradigm aiming at ensuring low latency in modern data intensive applications (e.g., video streaming and IoT). It consists of deploying computation and storage nodes close to the end-users. Unfortunately, being distributed and close to end-users, Edge systems have a wider attack surface (e.g., they may be physically reachable) and are more complex to update than other types of systems (e.g., Cloud systems) thus requiring thorough security testing activities, possibly tailored to be cost-effective. To support the development of effective and automated Edge security testing solutions, we conducted an empirical study of vulnerabilities affecting Edge frameworks. The study is driven by eight research questions that aim to determine what test triggers, test harnesses, test oracles, and input types should be considered when defining new security testing approaches dedicated to Edge systems. preconditions and inputs leading to a successful exploit, the security properties being violated, the most frequent vulnerability types, the software behaviours and developer mistakes associated to these vulnerabilities, and the severity of Edge vulnerabilities. We have inspected 147 vulnerabilities of four popular Edge frameworks. Our findings indicate that vulnerabilities slip through the testing process because of the complexity of the Edge features. Indeed, they can’t be exhaustively tested in-house because of the large number of combinations of inputs, outputs, and interfaces to be tested. Since we observed that most of the vulnerabilities do not affect the system integrity and, further, only one action (e.g., requesting a URL) is sufficient to exploit a vulnerability

Deep neural networks (DNNs) have demonstrated superior performance over classical machine learning to support many features in safety-critical systems. Although DNNs are now widely used in such systems (e.g., self driving cars), there is limited progress regarding automated support for functional safety analysis in DNN-based systems. For example, the identification of root causes of errors, to enable both risk analysis and DNN retraining, remains an open problem. In this article, we propose SAFE, a black-box approach to automatically characterize the root causes of DNN errors. SAFE relies on a transfer learning model pre-trained on ImageNet to extract the features from error-inducing images. It then applies a density-based clustering algorithm to detect arbitrary shaped clusters of images modeling plausible causes of error. Last, clusters are used to effectively retrain and improve the DNN. The black-box nature of SAFE is motivated by our objective not to require changes or even access to the DNN internals to facilitate adoption. Experimental results show the superior ability of SAFE in identifying different root causes of DNN errors based on case studies in the automotive domain. It also yields significant improvements in DNN accuracy after retraining, while saving significant execution time and memory when compared to alternatives.

When Deep Neural Networks (DNNs) are used in safety-critical systems, engineers should determine the safety risks associated with failures (i.e., erroneous outputs) observed during testing. For DNNs processing images, engineers visually inspect all failure-inducing images to determine common characteristics among them. Such characteristics correspond to hazard-triggering events (e.g., low illumination) that are essential inputs for safety analysis. Though informative, such activity is expensive and error prone. To support such safety analysis practices, we propose Simulator-based Explanations for DNN failurEs (SEDE), a technique that generates readable descriptions for commonalities in failure-inducing, real-world images and improves the DNN through effective retraining. SEDE leverages the availability of simulators, which are commonly used for cyber-physical systems. It relies on genetic algorithms to drive simulators toward the generation of images that are similar to failure-inducing, real-world images in the test set; it then employs rule learning algorithms to derive expressions that capture commonalities in terms of simulator parameter values. The derived expressions are then used to generate additional images to retrain and improve the DNN. With DNNs performing in-car sensing tasks, SEDE successfully characterized hazard-triggering events leading to a DNN accuracy drop. Also, SEDE enabled retraining leading to significant improvements in DNN accuracy, up to 18 percentage points.

Security testing aims at verifying that the software meets its security properties. In modern Web systems, however, this often entails the verification of the outputs generated when exercising the system with a very large set of inputs. Full automation is thus required to lower costs and increase the effectiveness of security testing. Unfortunately, to achieve such automation, in addition to strategies for automatically deriving test inputs, we need to address the oracle problem, which refers to the challenge, given an input for a system, of distinguishing correct from incorrect behavior (e.g., the response to be received after a specific HTTP GET request). In this paper, we propose Metamorphic Security Testing for Web-interactions (MST-wi), a metamorphic testing approach that integrates test input generation strategies inspired by mutational fuzzing and alleviates the oracle problem in security testing. It enables engineers to specify metamorphic relations (MRs) that capture many security properties of Web systems. To facilitate the specification of such MRs, we provide a domain-specific language accompanied by an Eclipse editor.MST-wiautomatically collects the input data and transforms the MRs into executable Java code to automatically perform security testing. It automatically tests Web systems to detect vulnerabilities based on the relations and collected data. We provide a catalog of 76 system-agnostic MRs to automate security testing in Web systems. It covers 39% of the OWASP security testing activities not automated by state-of-the-art techniques; further, our MRs can automatically discover 102 different types of vulnerabilities, which correspond to 45% of the vulnerabilities due to violations of security design principles according to the MITRE CWE database. We also define guidelines that enable test engineers to improve the testability of the system under test with respect to our approach. We evaluatedMST-wieffectiveness and scalability with two well-known Web systems (i.e., Jenkins and Joomla). It automatically detected 85% of their vulnerabilities and showed a high specificity (99.81% of the generated inputs do not lead to a false positive); our findings include a new security vulnerability detected in Jenkins. Finally, our results demonstrate that the approach scale, thus enabling automated security testing overnight.

Cyber-physical systems (CPSs) typically consist of a wide set of integrated, heterogeneous components; consequently, most of their critical failures relate to the interoperability of such components. Unfortunately, most CPS test automation techniques are preliminary and industry still heavily relies on manual testing. With potentially incomplete, manually-generated test suites, it is of paramount importance to assess their quality. Though mutation analysis has demonstrated to be an effective means to assess test suite quality in some specific contexts, we lack approaches for CPSs. Indeed, existing approaches do not target interoperability problems and cannot be executed in the presence of black-box or simulated components, a typical situation with CPSs. In this article, we introducedata-driven mutation analysis, an approach that consists in assessing test suite quality by verifying if it detects interoperability faults simulated by mutating the data exchanged by software components. To this end, we describe a data-driven mutation analysis technique (DaMAT) that automatically alters the data exchanged through data buffers. Our technique is driven by fault models in tabular form where engineers specify how to mutate data items by selecting and configuring a set of mutation operators. We have evaluatedDaMATwith CPSs in the space domain; specifically, the test suites for the software systems of a microsatellite and nanosatellites launched on orbit last year. Our results show that the approach effectively detects test suite shortcomings, is not affected by equivalent and redundant mutants, and entails acceptable costs.

We are pleased to welcome you to the 33rd edition of the International Symposium on Software Reliability Engineering (ISSRE 2022) and its innovative and diverse research program. This edition received 162 submissions from 25 countries. This included technical regular papers (REG), practical experience reports (PER) and tools and artifact papers (TAR). Of the 162 submissions, 47 were accepted (acceptance rate of 29%).

App testing tools tend to generate thousand test inputs; they help engineers identify crashing conditions but not functional failures. Indeed, detecting functional failures requires the visual inspection of App outputs, which is infeasible for thousands of inputs. Existing App testing tools ignore that most of the Apps are frequently updated and engineers are mainly interested in testing the updated functionalities; indeed, automated regression test cases can be used otherwise. We present ATUA, an open source tool targeting Android Apps. It achieves high coverage of the updated App code with a small number of test inputs, thus alleviating the test oracle problem (less outputs to inspect). It implements a model-based approach that synthesizes App models with static analysis, integrates a dynamically-refined state abstraction function and combines complementary testing strategies, including (1) coverage of the model structure, (2) coverage of the App code, (3) random exploration, and (4) coverage of dependencies identified through information retrieval. Our empirical evaluation, conducted with nine popular Android Apps (72 versions), has shown that ATUA, compared to state-of-the-art approaches, achieves higher code coverage while producing fewer outputs to be manually inspected. A demo video is available at https://youtu.be/RqQ1z_Nkaqo.

Apps’ pervasive role in our society led to the definition of test automation approaches to ensure their dependability. However, state-of-the-art approaches tend to generate large numbers of test inputs and are unlikely to achieve more than 50% method coverage. In this article, we propose a strategy to achieve significantly higher coverage of the code affected by updates with a much smaller number of test inputs, thus alleviating the test oracle problem. More specifically, we present ATUA, a model-based approach that synthesizes App models with static analysis, integrates a dynamically refined state abstraction function and combines complementary testing strategies, including (1) coverage of the model structure, (2) coverage of the App code, (3) random exploration, and (4) coverage of dependencies identified through information retrieval. Its model-based strategy enables ATUA to generate a small set of inputs that exercise only the code affected by the updates. In turn, this makes common test oracle solutions more cost-effective, as they tend to involve human effort. A large empirical evaluation, conducted with 72 App versions belonging to nine popular Android Apps, has shown that ATUA is more effective and less effort-intensive than state-of-the-art approaches when testing App updates.

On-board embedded software developed for spaceflight systems (space software) must adhere to stringent software quality assurance procedures. For example, verification and validation activities are typically performed and assessed by third party organizations. To further minimize the risk of human mistakes, space agencies, such as the European Space Agency (ESA), are looking for automated solutions for the assessment of software testing activities, which play a crucial role in this context. Though space software is our focus here, it should be noted that such software shares the above considerations, to a large extent, with embedded software in many other types of cyber-physical systems. Over the years, mutation analysis has shown to be a promising solution for the automated assessment of test suites; it consists of measuring the quality of a test suite in terms of the percentage of injected faults leading to a test failure. A number of optimization techniques, addressing scalability and accuracy problems, have been proposed to facilitate the industrial adoption of mutation analysis. However, to date, two major problems prevent space agencies from enforcing mutation analysis in space software development. First, there is uncertainty regarding the feasibility of applying mutation analysis optimization techniques in their context. Second, most of the existing techniques either can break the real-time requirements common in embedded software or cannot be applied when the software is tested in Software Validation Facilities, including CPU emulators and sensor simulators. In this paper, we enhance mutation analysis optimization techniques to enable their applicability to embedded software and propose a pipeline that successfully integrates them to address scalability and accuracy issues in this context, as described above. Further, we report on the largest study involving embedded software systems in the mutation analysis literature. Our research is part of a research project funded by ESA ESTEC involving private companies (GomSpace Luxembourg and LuxSpace) in the space sector. These industry partners provided the case studies reported in this paper; they include an on-board software system managing a microsatellite currently on-orbit, a set of libraries used in deployed cubesats, and a mathematical library certified by ESA.

To mitigate the cost of manually producing and maintaining models capturing software specifications,specification miningtechniques can be exploited to automatically derive up-to-date models that faithfully represent the behavior of software systems. So far, specification mining solutions focused on extracting information about the functional behavior of the system, especially in the form of models that represent the ordering of the operations. Well-known examples are finite state models capturing the usage protocol of software interfaces and temporal rules specifying relations among system events. Although the functional behavior of a software system is a primary aspect of concern, there are several other non-functional characteristics that must be typically addressed jointly with the functional behavior of a software system. Efficiency is one of the most relevant characteristics. Indeed, an application that delivers the right functionalities with an inefficient implementation may fail to satisfy the expectations of its users. Interestingly, thetiming behavioris strongly dependent on the functional behavior of a software system. For instance, the timing of an operation depends on the functional complexity and size of the computation that is performed. Consequently, models that combine the functional and timing behaviors, as well as their dependencies, are extremely important to precisely reason on the behavior of software systems. In this paper, we address the challenge of generating models that capture both the functional and timing behavior of a software system from execution traces. The result is theTimed k-Tail (TkT) specification mining technique, which can mine finite state models that capture such an interplay: the functional behavior is represented by the possible order of the events accepted by the transitions, while the timing behavior is represented through clocks and clock constraints of different nature associated with transitions. Our empirical evaluation with several libraries and applications shows thatTkTcan generate accurate models, capable of supporting the identification of timing anomalies due to overloaded environment and performance faults. Furthermore, our study shows thatTkToutperforms state-of-the-art techniques in terms of scalability and accuracy of the mined models.

Acceptance testing is a validation activity performed to ensure the conformance of software systems with respect to their functional requirements. In safety critical systems, it plays a crucial role since it is enforced by software standards, which mandate that each requirement be validated by such testing in a clearly traceable manner. Test engineers need to identify all the representative test execution scenarios from requirements, determine the runtime conditions that trigger these scenarios, and finally provide the input data that satisfy these conditions. Given that requirements specifications are typically large and often provided in natural language (e.g., use case specifications), the generation of acceptance test cases tends to be expensive and error-prone. In this paper, we present Use Case Modeling for System-level, Acceptance Tests Generation (UMTG), an approach that supports the generation of executable, system-level, acceptance test cases from requirements specifications in natural language, with the goal of reducing the manual effort required to generate test cases and ensuring requirements coverage. More specifically, UMTG automates the generation of acceptance test cases based on use case specifications and a domain model for the system under test, which are commonly produced in many development environments. Unlike existing approaches, it does not impose strong restrictions on the expressiveness of use case specifications. We rely on recent advances in natural language processing to automatically identify test scenarios and to generate formal constraints that capture conditions triggering the execution of the scenarios, thus enabling the generation of test data. In two industrial case studies, UMTG automatically and correctly translated 95 percent of the use case specification steps into formal constraints required for test data generation; furthermore, it generated test cases that exercise not only all the test scenarios manually implemented by experts, but also some critical scenarios not previously considered.

Deep neural networks (DNNs) are increasingly important in safety-critical systems, for example, in their perception layer to analyze images. Unfortunately, there is a lack of methods to ensure the functional safety of DNN-based components. We observe three major challenges with existing practices regarding DNNs in safety-critical systems: 1) Scenarios that are under-represented in the test set may lead to serious safety violation risks but may, however, remain unnoticed; 2) characterizing such high-risk scenarios is critical for safety analysis; 3) retraining DNNs to address these risks is poorly supported when causes of violations are difficult to determine. To address these problems in the context of DNNs analyzing images, we propose heatmap-based unsupervised debugging of DNNs (HUDD), an approach that automatically supports the identification of root causes for DNN errors. HUDD identifies root causes by applying a clustering algorithm to heatmaps capturing the relevance of every DNN neuron on the DNN outcome. Also, HUDD retrains DNNs with images that are automatically selected based on their relatedness to the identified image clusters. We evaluated HUDD with DNNs from the automotive domain. HUDD was able to identify all the distinct root causes of DNN errors, thus supporting safety analysis. Also, our retraining approach has shown to be more effective at improving DNN accuracy than existing approaches.

Security testing verifies that the data and the resources of software systems are protected from attackers. Unfortunately, it suffers from the oracle problem, which refers to the challenge, given an input for a system, of distinguishing correct from incorrect behavior. In many situations where potential vulnerabilities are tested, a test oracle may not exist, or it might be impractical due to the many inputs for which specific oracles have to be defined. In this paper, we propose a metamorphic testing approach that alleviates the oracle problem in security testing. It enables engineers to specify metamorphic relations (MRs) that capture security properties of the system. Such MRs are then used to automate testing and detect vulnerabilities. We provide a catalog of 22 system-agnostic MRs to automate security testing in Web systems. Our approach targets 39% of the OWASP security testing activities not automated by state-of-the-art techniques. It automatically detected 10 out of 12 vulnerabilities affecting two widely used systems, one commercial and the other open source (Jenkins).

Debugging Cyber-Physical System models is often challenging, as it requires identifying a potentially long, complex and heterogenous combination of events that resulted in a violation of the expected behavior of the system. In this paper we present CPSDebug, a tool for supporting designers in the debugging of failures in MATLAB Simulink/Stateflow models. CPSDebug implements a gray-box approach that combines testing, specification mining, and failure analysis to identify the causes of failures and explain their propagation in time and space. The evaluation of the tool, based on multiple usage scenarios and faults and direct feedback from engineers, shows that CPSDebug can effectively aid engineers during debugging tasks.

Acceptance criteria (AC) are implementation agnostic conditions that a system must meet to be consistent with its requirements and be accepted by its stakeholders. Each acceptance criterion is typically expressed as a natural-language statement with a clear pass or fail outcome. Writing AC is a tedious and error-prone activity, especially when the requirements specifications evolve and there are different analysts and testing teams involved. Analysts and testers must iterate multiple times to ensure that AC are understandable and feasible, and accurately address the most important requirements and workflows of the system being developed. In many cases, analysts express requirements through models, along with natural language, typically in some variant of the UML. AC must then be derived by developers and testers from such models. In this paper, we bridge the gap between requirements models and AC by providing a UML-based modeling methodology and an automated solution to generate AC. We target AC in the form of Behavioral Specifications in the context of Behavioral-Driven Development (BDD), a widely used agile practice in many application domains. More specially we target the well-known Gherkin language to express AC, which then can be used to generate executable test cases. We evaluate our modeling methodology and AC generation solution through an industrial case study in the financial domain. Our results suggest that (1) our methodology is feasible to apply in practice, and (2) the additional modeling effort required by our methodology is outweighed by the benefits the methodology brings in terms of automated and systematic AC generation and improved model precision.

Uncertainty in timing properties (e.g., detection time of external events) is a common occurrence in embedded software systems, since these systems interact with complex physical environments. Such time uncertainty leads to non-determinism. For example, time-triggered operations may either generate different valid outputs across different executions or experience failures (e.g., results not being generated in the expected time window) that occur only occasionally over many executions. For these reasons, time uncertainty makes the generation of effective test oracles for timing requirements a challenging task. To address the above challenge, we propose Stochastic Testing with Unique Input Output Sequences, an approach for the automated generation of stochastic oracles that verify the capability of a software system to fulfill timing constraints in the presence of time uncertainty. Such stochastic oracles entail the statistical analysis of repeated test case executions based on test output probabilities predicted by means of statistical model checking. Results from two industrial case studies in the automotive domain demonstrate that this approach improves the fault detection effectiveness of tests suites derived from timed automata compared to traditional approaches.

To facilitate communication among stakeholders, software security requirements are typically written in natural language and capture both positive requirements (i.e., what the system is supposed to do to ensure security) and negative requirements (i.e., undesirable behavior undermining security). In this paper, we tackle the problem of automatically generating executable security test cases from security requirements in natural language (NL). More precisely, since existing approaches for the generation of test cases from NL requirements verify only positive requirements, we focus on the problem of generating test cases from negative requirements. We propose, apply and assess Misuse Case Programming (MCP), an approach that automatically generates security test cases from misuse case specifications (i.e., use case specifications capturing the behavior of malicious users). MCP relies on natural language processing techniques to extract the concepts (e.g., inputs and activities) appearing in requirements specifications and generates executable test cases by matching the extracted concepts to the members of a provided test driver API. MCP has been evaluated in an industrial case study, which provides initial evidence of the feasibility and benefits of the approach.

Context: Modern internet-based services, ranging from food-delivery to home-caring, leverage the availability of multiple programmable devices to provide handy services tailored to end-user needs. These services are delivered through an ecosystem of device-specific software components and interfaces (e.g., mobile and wearable device applications). Since they often handle private information (e.g., location and health status), their security and privacy requirements are of crucial importance. Defining and analyzing those requirements is a significant challenge due to the multiple types of software components and devices integrated into software ecosystems. Each software component presents peculiarities that often depend on the context and the devices the component interact with, and that must be considered when dealing with security and privacy requirements. Objective: In this paper, we propose, apply, and assess a modeling method that supports the specification of security and privacy requirements in a structured and analyzable form. Our motivation is that, in many contexts, use cases are common practice for the elicitation of functional requirements and should also be adapted for describing security requirements. Method: We integrate an existing approach for modeling security and privacy requirements in terms of security threats, their mitigations, and their relations to use cases in a misuse case diagram. We introduce new security-related templates, i.e., a mitigation template and a misuse case template for specifying mitigation schemes and misuse case specifications in a structured and analyzable manner. Natural language processing can then be used to automatically report inconsistencies among artifacts and between the templates and specifications. Results: We successfully applied our approach to an industrial healthcare project and report lessons learned and results from structured interviews with engineers. Conclusion: Since our approach supports the precise specification and analysis of security threats, threat scenarios and their mitigations, it also supports decision making and the analysis of compliance to standards.

Accurate and up-to-date models describing the behavior of software systems are seldom available in practice. To address this issue, software engineers may use specification mining techniques, which can automatically derive models that capture the behavior of the system under analysis. So far, most specification mining techniques focused on the functional behavior of the systems, with specific emphasis on models that represent the ordering of operations, such as temporal rules and finite state models. Although useful, these models are inherently partial. For instance, they miss the timing behavior, which is extremely relevant for many classes of systems and components, such as shared libraries and user-driven applications. Mining specifications that include both the functional and the timing aspects can improve the applicability of many testing and analysis solutions. This paper addresses this challenge by presenting the Timed k-Tail (TkT) specification mining technique that can mine timed automata from program traces. Since timed automata can effectively represent the interplay between the functional and the timing behavior of a system, TkT could be exploited in those contexts where time-related information is relevant. Our empirical evaluation shows that TkT can efficiently and effectively mine accurate models. The mined models have been used to identify executions with anomalous timing. The evaluation shows that most of the anomalous executions have been correctly identified while producing few false positives.

In the context of use-case centric development and requirements-driven testing, this paper addresses the problem of automatically deriving system test cases to verify timing requirements. Inspired by engineering practice in an automotive software development context, we rely on an analyzable form of use case specifications and augment such functional descriptions with timed automata, capturing timing requirements, following a methodology aiming at minimizing modeling overhead. We automate the generation of executable test cases using a test strategy based on maximizing test suite diversity and building over the UPPAAL model checker. Initial empirical results based on an industrial case study provide evidence of the effectiveness of the approach.

Field failures, that is, failures caused by faults that escape the testing phase leading to failures in the field, are unavoidable. Improving verification and validation activities before deployment can identify and timely remove many but not all faults, and users may still experience a number of annoying problems while using their software systems.This paper investigates the nature of field failures, to understand to what extent further improving in-house verification and validation activities can reduce the number of failures in the field, and frames the need of new approaches that operate in the field.We report the results of the analysis of the bug reports of five applications belonging to three different ecosystems, propose a taxonomy of field failures, and discuss the reasons why failures belonging to the identified classes cannot be detected at design time but shall be addressed at runtime. We observe that many faults (70%) are intrinsically hard to detect at design-time.

In this paper we present VART, a tool for automatically revealing regression faults missed by regression test suites. Interestingly, VART is not limited to faults causing crashing or exceptions, but can reveal faults that cause the violation of application-specific correctness properties. VART achieves this goal by combining static and dynamic program analysis.

Source Code Management (SCM) systems support software evolution by providing features, such as version control, branching, and conflict detection. Despite the presence of these features, support to parallel software development is often limited. SCM systems can only address a subset of the conflicts that might be introduced by developers when concurrently working on multiple parallel branches. In fact, SCM systems can detect textual conflicts, which are generated by the concurrent modification of the same program locations, but they are unable to detect higher-order conflicts, which are generated by the concurrent modification of different program locations that generate program misbehaviors once merged. Higher-order conflicts are painful to detect and expensive to fix because they might be originated by the interference of apparently unrelated changes.

When testing data processing systems, software engineers often use real-world data to perform system-level testing. However, in the presence of new data requirements, software engineers may no longer benefit from having real-world data with which to perform testing. Typically, new test inputs complying with the new requirements have to be manually written. We propose an automated model-based approach that combines data modelling and constraint solving to modify existing field data to generate test inputs for testing new data requirements. The approach scales in the presence of complex and structured data, thanks to both the reuse of existing field data and the adoption of an innovative input generation algorithm based on slicing the model into parts. We validated the scalability and effectiveness of the proposed approach using an industrial case study. The empirical study shows that the approach scales in the presence of large amounts of structured and complex data. The approach can produce, within a reasonable time, test input data that is over ten times larger in size than the data generated with constraint solving only. We also demonstrate that the generated test inputs achieve more code coverage than the test cases implemented by experienced software engineers.

Automatic testing, although useful, is still quite ineffective against faults that do not cause crashes or uncaught exceptions. In the majority of the cases automatic tests do not include oracles, and only in some cases they incorporate assertions that encode the observed behavior instead of the intended behavior, that is if the application under test produces a wrong result, the synthesized assertions will encode wrong expectations that match the actual behavior of the application. In this paper we present Zoom In, a technique that extends the fault-revealing capability of test case generation techniques from crash-only faults to faults that require non-trivial oracles to be detected. Zoom In exploits the knowledge encoded in the manual tests written by developers and the similarity between executions to automatically determine an extremely small set of suspicious assertions that are likely wrong and thus worth manual inspection. Early empirical results show that Zoom In has been able to detect 50% of the analyzed non-crashing faults in the Apache Commons Math library requiring the inspection of less than 1.5% of the assertions automatically generated by EvoSuite.

Testing the correct behaviour of data processing systems in the presence of faulty data is extremely expensive. The data structures processed by these systems are often complex, with many data fields and multiple constraints among them. Software engineers, in charge of testing these systems, have to handcraft complex data files or databases, while ensuring compliance with the multiple constraints to prevent the generation of trivially invalid inputs. In addition, assessing test results often means analysing complex output and log data. Though many techniques have been proposed to automatically test systems based on models, little exists in the literature to support the testing of systems where the complexity is in the data consumed in input or produced in output, with complex constraints between them. In particular, such systems often need to be tested with the presence of faults in the input data, in order to assess the robustness and behaviour of the system in response to such faults. This paper presents an automated test technique that relies upon six generic mutation operators to automatically generate faulty data. The technique receives two inputs: field data and a data model, i.e. a UML class diagram annotated with stereotypes and OCL constraints. The annotated class diagram is used to tailor the behaviour of the generic mutation operators to the fault model that is assumed for the system under test and the environment in which it is deployed. Empirical results obtained with a large data acquisition system in the satellite domain show that our approach can successfully automate the generation of test suites that achieve slightly better instruction coverage than manual testing based on domain expertise.

In safety critical domains, system test cases are often derived from functional requirements in natural language (NL) and traceability between requirements and their corresponding test cases is usually mandatory. The definition of test cases is therefore time-consuming and error prone, especially so given the quickly rising complexity of embedded systems in many critical domains. Though considerable research has been devoted to automatic generation of system test cases from NL requirements, most of the proposed approaches re- quire significant manual intervention or additional, complex behavioral modelling. This significantly hinders their applicability in practice. In this paper, we propose Use Case Modelling for System Tests Generation (UMTG), an approach that automatically generates executable system test cases from use case spec- ifications and a domain model, the latter including a class diagram and constraints. Our rationale and motivation are that, in many environments, including that of our industry partner in the reported case study, both use case specifica- tions and domain modelling are common and accepted prac- tice, whereas behavioural modelling is considered a difficult and expensive exercise if it is to be complete and precise. In order to extract behavioral information from use cases and enable test automation, UMTG employs Natural Language Processing (NLP), a restricted form of use case specifica- tions, and constraint solving.

System level testing of industrial data processing software poses several challenges. Input data can be very large, even in the order of gigabytes, and with complex constraints that define when an input is valid. Generating the right input data to stress the system for robustness properties (e.g. to test how faulty data is handled) is hence very complex, tedious and error prone when done manually. Unfortunately, this is the current practice in industry. In previous work, we defined a methodology to model the structure and the constraints of input data by using UML class diagrams and OCL constraints. Tests were automatically derived to cover predefined fault types in a fault model. In this paper, to obtain more effective system level test cases, we developed a novel search-based test generation tool. Experiments on a real-world, large industrial data processing system show that our automated approach can not only achieve better code coverage, but also accomplishes this using significantly smaller test suites.

We present UMTG, a toolset for automatically generating executable and traceable system test cases from use case specifications. UMTG employs Natural Language Processing (NLP), a restricted form of use case specifications, and constraint solving. Use cases are expected to follow a template with restriction rules that reduce imprecision and enable NLP. NLP is used to capture the control flow implicitly described in use case specifications. Finally, to generate test input, constraint solving is applied to OCL constraints referring to the domain model of the system. UMTG is integrated with two tools that are widely adopted in industry, IBM Doors and Rhapsody. UMTG has been successfully evaluated on an industrial case study.

In this paper we present Verification-Aided Regression Testing (VART), a novel extension of regression testing that uses model checking to increase the fault revealing capability of existing test suites. The key idea in VART is to extend the use of test case executions from the conventional direct fault discovery to the generation of behavioral properties specific to the upgrade, by (i) automatically producing properties that are proved to hold for the base version of a program, (ii) automatically identifying and checking on the upgraded program only the properties that, according to the developers’ intention, must be preserved by the upgrade, and (iii) reporting the faults and the corresponding counter-examples that are not revealed by the regression tests. Our empirical study on both open source and industrial software systems shows that VART automatically produces properties that increase the effectiveness of testing by automatically detecting faults unnoticed by the existing regression test suites.

Automated debugging techniques aim to help developers locate and understand the cause of a failure, an extremely challenging yet fundamental task. Most state-of-the-art approaches suffer from two problems: they require a large number of passing and failing tests and report possible faulty code with no explanation. To mitigate these issues, we present MIMIC, a novel automated debugging technique that combines and extends our previous input generation and anomaly detection techniques. MIMIC (1) synthesizes multiple passing and failing executions similar to an observed failure and (2) uses these executions to detect anomalies in behavior that may explain the failure. We evaluated MIMIC on six failures of real-world programs with promising results: for five of these failures, MIMIC identified their root causes while producing a limited number of false positives. Most importantly, the anomalies identified by MIMIC provided information that may help developers understand (and ultimately eliminate) such root causes.

SUMMARY Software systems evolve incrementally both during and after development, and many test cases become obsolete while software evolves. Updating test suites in the context of software evolution is a complex and time consuming activity. This article focuses on the problem of updating test suites automatically, and identifies eight scenarios that allow either to repair test cases or to use test cases to generate new ones, and proposes eight test evolution algorithms that automatically repair and generate test cases by adapting existing ones. This article presents a framework, TestCareAssistant (TCA), that implements the algorithms to support the evolution of test suites written in Java. The framework has been extensively evaluated on five different open source projects where it has been applied to repair 138 broken test cases, and to generate the test cases for 727 new classes and 2462 new methods. The results obtained with TCA indicate that the approach can successfully repair 90% of the broken test cases, create test cases that cover a large amount of code and complement the test cases that can be generated by state of the art techniques. Copyright © 2014 John Wiley & Sons, Ltd.

Multiple tools can assist developers when debugging programs, but only a few solutions specifically target the common case of regression failures, to provide a more focused and effective support to debugging. In this paper we present RADAR, a tool that combines change identification and dynamic analysis to automatically explain regression problems with a list of suspicious differences in the behavior of the base and upgraded version of a program. The output produced by the tool is particularly beneficial to understand why an application failed. A demo video is available at http://www.youtube.com/watch?v=DMGUgALG-yE.

Several debugging techniques can be used to automatically identify the code fragments or the runtime events likely responsible of a failure. These techniques are useful, but can help reducing the debugging effort only to a given extent. In fact, even when these techniques are successful, software developers still have to invest a lot of effort in understanding if and why something detected as suspicious is really wrong. In this paper we present the tool implementing the AVA technique. AVA, compared to other approaches dedicated to automatic debugging, in addition to automatically identifying the events likely responsible of a failure, generates an explanation about why these events have been considered suspicious. This explanation can be used by developers to quickly discard imprecise outputs and more effectively work on the relevant anomalies.

Despite the recent advances in test generation, fully automatic software testing remains a dream: Ultimately, any generated test input depends on a test oracle that determines correctness, and, except for generic properties such as “the program shall not crash”, such oracles require human input in one form or another. CrowdSourcing is a recently popular technique to automate computations that cannot be performed by machines, but only by humans. A problem is split into small chunks, that are then solved by a crowd of users on the Internet. In this paper we investigate whether it is possible to exploit CrowdSourcing to solve the oracle problem: We produce tasks asking users to evaluate CrowdOracles - assertions that reflect the current behavior of the program. If the crowd determines that an assertion does not match the behavior described in the code documentation, then a bug has been found. Our experiments demonstrate that CrowdOracles are a viable solution to automate the oracle problem, yet taming the crowd to get useful results is a difficult task.

SUMMARY Integrating tools implemented as plug‐ins is a complex and time‐consuming activity that requires good programming skills and a deep understanding of the underlying plug‐in architecture for successful completion. Even when tools are implemented as plug‐ins for a same integrated development environment (IDE), users frequently prefer to manually perform the same inefficient operations every time they use the tools rather than implementing automated tool integration. In our vision, IDE users must be able to flexibly execute plug‐ins and easily integrate their results by designing workflows that can be persisted, automatically executed, and reused in other workflows. This paper therefore presents MASH, a framework that extends IDEs with task‐based plug‐ins (TB‐plug‐ins) and workflows. A TB‐plug‐in is a plug‐in that exposes its functionalities as executable tasks in a workflow. TB‐plug‐in workflows are processes that automatically execute multiple tools and integrate their results. IDE users can turn regular plug‐ins into TB‐plug‐ins by writing simple scripts or using the GUI capturing feature that MASH offers. We validated our idea with two case studies examining the design of two data‐driven analyses as tool integration. We discovered that workflows can be easily designed by knowing little about the IDE or plug‐ins API, saving significant effort otherwise devoted to implementing additional plug‐ins and glue code, and they produce analyses that can be quickly modified and reused. Copyright © 2012 John Wiley & Sons, Ltd.

Most of the modern Integrated Development Environments are developed with plug-in based architectures that can be extended with additional functionalities and plug-ins, according to user needs. However, extending an IDE is still a possibility restricted to developers with deep knowledge about the specific development environment and its architecture. In this paper we present MASH, a tool that eases the programming of Integrated Development Environments. The tool supports the definition of workflows that can be quickly designed to integrate functionalities offered by multiple plugins, without the need of knowing anything about the internal architecture of the IDE. Workflows can be easily reshaped every time an analysis must be modified, without the need of producing Java code and deploying components in the IDE. Early results suggest that this approach can effectively facilitate programming of IDEs.

Software systems evolve during development and maintenance, and many test cases designed for the early versions of the system become obsolete during the software lifecycle. Repairing test cases that do not compile due to changes in the code under test and generating new test cases to test the changed code is an expensive and time consuming activity that could benefit from automated approaches. In this paper we propose an approach for automatically repairing and generating test cases during software evolution. Differently from existing approaches to test case generation, our approach uses information available in existing test cases, defines a set of heuristics to repair test cases invalidated by changes in the software, and generate new test cases for evolved software. The results obtained with a prototype implementation of the technique show that the approach can effectively maintain evolving test suites, and perform well compared to competing approaches.

Regression testing techniques are commonly used to validate the correctness of upgrades. When a regression test fails, testers must understand the erroneous behaviors that caused the failure and identify the fault that originated these erroneous behaviors. In many cases, identifying the causes of a failure is difficult and time consuming. The analysis of regression problems provides interesting opportunities to validation and verification techniques. In fact, by comparing the execution of the base version and the upgraded version of the same program it is possible to automatically deduce information about incorrect behavior of the program. In this paper we present RADAR (Regression Analysis with Diff And Recording), a dynamic analysis technique, which analyzes regression problems and automatically identifies the chain of erroneous events that lead to a failure in C/C++ programs. RADAR exploits information about changes and the availability of multiple versions of the same program to automatically distinguish correct and suspicious events. Empirical experience with industrial and open source cases shows that RADAR can effectively support testers in the investigation of regression problems. Thus, RADAR can drive and simplify the debugging process.

Many software components are provided with incomplete specifications and little access to the source code. Reusing such gray-box components can result in integration faults that can be difficult to diagnose and locate. In this paper, we present Behavior Capture and Test (BCT), a technique that uses dynamic analysis to automatically identify the causes of failures and locate the related faults. BCT augments dynamic analysis techniques with model-based monitoring. In this way, BCT identifies a structured set of interactions and data values that are likely related to failures (failure causes), and indicates the components and the operations that are likely responsible for failures (fault locations). BCT advances scientific knowledge in several ways. It combines classic dynamic analysis with incremental finite state generation techniques to produce dynamic models that capture complementary aspects of component interactions. It uses an effective technique to filter false positives to reduce the effort of the analysis of the produced data. It defines a strategy to extract information about likely causes of failures by automatically ranking and relating the detected anomalies so that developers can focus their attention on the faults. The effectiveness of BCT depends on the quality of the dynamic models extracted from the program. BCT is particularly effective when the test cases sample the execution space well. In this paper, we present a set of case studies that illustrate the adequacy of BCT to analyze both regression testing failures and rare field failures. The results show that BCT automatically filters out most of the false alarms and provides useful information to understand the causes of failures in 69 percent of the case studies.

When software systems evolve, for example due to fault fixes, modification of functionalities or refactoring activities, test cases may become obsolete thus generating wrong results or even not being executable or compilable. Maintaining test cases is expensive and time consuming, and often test cases are discarded by software developers due to high maintenance costs. This paper presents TestCareAssistant, a technique that combines data-flow analysis with program diffing for automatically repairing test cases that become obsolete because of changes in method declarations (addition, removal, or type modification of parameters or return values). The paper illustrates the efficacy of TestCareAssistant by analyzing the impact of method declarations changes on the executability of test cases, and by presenting the preliminary results of applying TestCareAssistant to repair 22 test cases.

Classic fault localization techniques can automatically provide information about the suspicious code blocks that are likely responsible for observed failures. This information is useful, but not sufficient to completely understand the causes of failing executions, which still require further (time-consuming) investigations to be exactly identified. A useful and comprehensive source of information is frequently given by the set of unexpected events that have been observed during failures. Sequences of unexpected events are usually simple to be interpret, and testers can guess the expected correct sequences of events from the faulty sequences. In this paper, we present a tool that automatically identifies anomalous events that likely caused failures, filters the possible false positives, and presents the resulting data by building views that show chains of cause-effect relations, i.e., views that show when anomalous events are caused by other anomalous events. The use of the technique to investigate a fault in the Tomcat application server is also presented in the paper.

Dynamic analysis techniques have been extensively adopted to discover causes of observed failures. In particular, anomaly detection techniques can infer behavioral models from observed legal executions and compare failing executions with the inferred models to automatically identify the likely anomalous events that caused observed failures.

Log files are commonly inspected by system administrators and developers to detect suspicious behaviors and diagnose failure causes. Since size of log files grows fast, thus making manual analysis impractical, different automatic techniques have been proposed to analyze log files. Unfortunately, accuracy and effectiveness of these techniques are often limited by the unstructured nature of logged messages and the variety of data that can be logged.This paper presents a technique to automatically analyze log files and retrieve important information to identify failure causes. The technique automatically identifies dependencies between events and values in logs corresponding to legal executions, generates models of legal behaviors and compares log files collected during failing executions with the generated models to detect anomalous event sequences that are presented to users. Experimental results show the effectiveness of the technique in supporting developers and testers to identify failure causes.