Automatically generating complex test cases from simple ones

While source code expresses and implements design considerations for software system, test cases capture and represent the domain knowledge of software developer, her assumptions on the implicit and explicit interaction protocols in the system, and the expected behavior of different modules of the system in normal and exceptional conditions. Moreover, test cases capture information about the environment and the data the system operates on. As such, together with the system source code, test cases integrate important system and domain knowledge. Besides being an important project artifact, test cases embody up to the half the overall software development cost and effort. Software projects produce many test cases of different kind and granularity to thoroughly check the system functionality, aiming to prevent, detect, and remove different types of faults. Simple test cases exercise small parts of the system aiming to detect faults in single modules. More complex integration and system test cases exercise larger parts of the system aiming to detect problems in module interactions and verify the functionality of the system as a whole. Not surprisingly, the test case complexity comes at a cost -- developing complex test cases is a laborious and expensive task that is hard to automate. Our intuition is that important information that is naturally present in test cases can be reused to reduce the effort in generation of new test cases. This thesis develops this intuition and investigates the phenomenon of information reuse among test cases. We first empirically investigated many test cases from real software projects and demonstrated that test cases of different granularity indeed share code fragments and build upon each other. Then we proposed an approach for automatically generating complex test cases by extracting and exploiting information in existing simple ones. In particular, our approach automatically generates integration test cases from unit ones. We implemented our approach in a prototype to evaluate its ability to generate new and useful test cases for real software systems. Our studies show that test cases generated with our approach reveal new interaction faults even in well tested applications. We evaluated the effectiveness of our approach by comparing it with the state of the art test generation techniques. The evaluation results show that our approach is effective, it finds relevant faults differently from other approaches that tend to find different and usually less relevant faults

Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element Vtb\bf V_{tb}

We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb$^{−1}$ per experiment. The t-channel cross section is measured to be σ$_t$=2.25$_{-0.31}^{+0.29}$ pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in σ$_{s+t}$=3.30$_{-0.40}^{+0.52}$ pb, without assuming the standard model value for the ratio σ$_s$/σ$_t$. The resulting value of the magnitude of the top-to-bottom quark coupling is |V$_{tb}$|=1.02$_{-0.05}^{+0.06}$, corresponding to |V$_{tb}$|>0.92 at the 95% C.L

Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

International audienceThe CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of s=1.96  TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is AFBtt¯=0.128±0.025. The combined inclusive and differential asymmetries are consistent with recent standard model predictions

Tevatron Run II combination of the effective leptonic electroweak mixing angle

International audienceDrell-Yan lepton pairs produced in the process pp¯→ℓ+ℓ-+X through an intermediate γ*/Z boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter sin2θefflept using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to 9–10  fb-1 of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, sin2θefflept=0.23148±0.00033. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter sin2θW, or equivalently the W-boson mass MW, using the zfitter software package yields sin2θW=0.22324±0.00033 or equivalently, MW=80.367±0.017  GeV/c2