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Open Access Publications from the University of California

Scholarly Works (4 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2017)

In recent years, there has been a significant surge in the use and development of apps for smartphones and tablets. The complexity of mobile apps mostly lies in their graphical user interfaces (GUIs) since the computational part of these apps are either simple or is delegated to a backend server. Therefore, testing efforts of these apps mostly focus on the behavior of graphical user interfaces.

In this thesis, we address two problems in GUI testing, test suite generation and test suite reduction, in the context of Android apps. In the first part of the thesis, we propose the SwiftHand algorithm for automatically generating sequences of test inputs for GUI apps. The algorithm uses machine learning to learn a model of the app during testing, uses the learned model to generate user inputs that visit unexplored states of the app, and uses the execution of the app on the generated inputs to refine the model. A key feature of the algorithm is that it avoids restarting the app, which is a significantly more expensive operation than executing the app on a sequence of inputs. We evaluate SwiftHand on several Android apps, showing that it can outperform a simple fuzz-testing algorithm and a traditional active-learning based testing algorithm.

In the second part of the thesis, we address the problem of reducing GUI test suites generated by automated testing tools. Automated testing tools, including SwiftHand, have been shown to be effective in achieving good test coverage and in finding bugs. Being automated, these tools typically run for a long period, e.g. for several hours, until the time budget for testing expires. However, these tools are not good at generating concise regression test suites that could be used for testing in incremental development of the apps and in regression testing. We propose DetReduce, a heuristic technique that helps to create a small regression test suite for a GUI app given a large test suite generated by running an automated GUI testing tool. The key insight is that if we can identify and remove some common forms of redundancies introduced by existing automated GUI testing tools, then we can drastically lower the time required to minimize a GUI test suite. We evaluate DetReduce on several Android apps, showing that it can reduce the size and running time of an automatically generated test suite by at least an order of magnitude.

    Cover page: Guided GUI Testing of Android Apps with Minimal Restart and Approximate Learning
    • Article
    Activity Descriptions (2022)
    We present highlights from a series of hands-on physics lab modules developed for remote teaching. The labs were composed of multiple self-guided inquiry modules. Though the labs were developed from scratch, some modules that were central to the design process were borrowed from previous PDP sessions and the guiding PDP principles of mirroring authentic Science, Technology, Engineering, and Mathematics (STEM) practices (e.g., allowing students to raise questions and take ownership of decision making). One notable aspect of this work is that by sourcing and assembling low-cost ($25 per student) lab kits that were sent to each student, the majority of the modules were hands-on despite being fully online. Combining online resources and simulation tools with individual hardware kits and small lab groups allowed for a mix of synchronous and asynchronous exploration. This mixed lab mode was successful in promoting both inquiry exploration and community building. One example of a lab design choice aimed at overcoming online barriers was that in lieu of weekly lab write-ups, groups submitted video checkouts in which students were encouraged to reflect on the lab, self-assess their learning outcomes, and highlight unique aspects of their lab experience. This lab was specifically developed in response to the unforeseen challenges of online teaching; however, multiple aspects of the course will seamlessly transfer to an in-person lab setting.
      Cover page: Self-guided Inquiry Modules for the Remote Teaching of Undergraduate Physics LabsCreative Commons 'BY' version 4.0 license
      • Article
      Activity Descriptions (2022)
      Classification is a general tool of science; it is used to sort and categorize biological organisms, chemical elements, astronomical objects, and many other things. In scientific classification, taxonomy often reflects shared physical properties that, in turn, may indicate shared origins and/or evolution. A “hands-on” galaxy-classification activity developed and implemented by Professional Development Program (PDP) participants, for a high-school summer STEM enrichment program, has been adopted for various age groups and venues, from young (K–3) to college students. We detail the basic tools required, outline the general activity, and describe the modifications to the activity based on learners’ ages and learning objectives. We describe the facilitation strategies learned through PDP training and used when implementing the activity, including prompts to motivate the students. We also discuss how we connected the classification process to astronomy and science more broadly during the concluding remarks.
        Cover page: Galaxy-Classification Activity for All AgesCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Berkeley Previously Published Works (2017)
        Cyclic diadenosine monophosphate (c-di-AMP) is a conserved nucleotide second messenger critical for bacterial growth and resistance to cell wall-active antibiotics. In Listeria monocytogenes, the sole diadenylate cyclase, DacA, is essential in rich, but not synthetic media and ΔdacA mutants are highly sensitive to the β-lactam antibiotic cefuroxime. In this study, loss of function mutations in the oligopeptide importer (oppABCDF) and glycine betaine importer (gbuABC) allowed ΔdacA mutants to grow in rich medium. Since oligopeptides were sufficient to inhibit growth of the ΔdacA mutant we hypothesized that oligopeptides act as osmolytes, similar to glycine betaine, to disrupt intracellular osmotic pressure. Supplementation with salt stabilized the ΔdacA mutant in rich medium and restored cefuroxime resistance. Additional suppressor mutations in the acetyl-CoA binding site of pyruvate carboxylase (PycA) rescued cefuroxime resistance and resulted in a 100-fold increase in virulence of the ΔdacA mutant. PycA is inhibited by c-di-AMP and these mutations prompted us to examine the role of TCA cycle enzymes. Inactivation of citrate synthase, but not down-stream enzymes suppressed ΔdacA phenotypes. These data suggested that c-di-AMP modulates central metabolism at the pyruvate node to moderate citrate production and indeed, the ΔdacA mutant accumulated six times the concentration of citrate present in wild-type bacteria.
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