Oracle Assessment, Improvement and Placement

The oracle problem remains one of the key challenges in software testing, for which little automated support has been developed so far. This thesis analyses the prevalence of failed error propagation in programs with real faults to address the oracle placement problem and introduces an approach for iterative assessment and improvement of the oracles. To analyse failed error propagation in programs with real faults, we have conducted an empirical study, considering Defects4J, a benchmark of Java programs, of which we used all 6 projects available, 384 real bugs and 528 methods fixed to correct such bugs. The results indicate that the prevalence of failed error propagation is negligible. Moreover, the results on real faults differ from the results on mutants, indicating that if failed error propagation is taken into account, mutants are not a good surrogate of real faults. When measuring failed error propagation, for each method we use the strongest possible oracle as postcondition, which checks all externally observable program variables. The low prevalence of failed error propagation is caused by the presence of such a strong oracle, which usually is not available in practice. Therefore, there is a need for a technique to assess and improve existing weaker oracles. We propose a technique for assessing and improving test oracles, which necessarily places the human tester in the loop and is based on reducing the incidence of both false positives and false negatives. A proof showing that this approach results in an increase in the mutual information between the actual and perfect oracles is provided. The application of the approach to five real-world subjects shows that the fault detection rate of the oracles after improvement increases, on average, by 48.6%. The further evaluation with 39 participants assessed the ability of humans to detect false positives and false negatives manually, without any tool support. The correct classification rate achieved by humans in this case is poor (29%) indicating how helpful our automated approach can be for developers. The comparison of humans’ ability to improve oracles with and without the tool in a study with 29 other participants also empirically validates the effectiveness of the approach

Test oracle assessment and improvement

We introduce a technique for assessing and improving test oracles by reducing the incidence of both false positives and false negatives. We prove that our approach can always result in an increase in the mutual information between the actual and perfect oracles. Our technique combines test case generation to reveal false positives and mutation testing to reveal false negatives. We applied the decision support tool that implements our oracle improvement technique to five real-world subjects. The experimental results show that the fault detection rate of the oracles after improvement increases, on average, by 48.6% (86% over the implicit oracle). Three actual, exposed faults in the studied systems were subsequently confirmed and fixed by the developers

Al-P-Cds/N-Cds/Zn1-Xcdxs Structures for Solar Cells

In this paper we report some properties of thin film photocells prepared on the basis of Al/p-CdS/n-CdS/Zn1-xCdxS heterojunctions. These heterojunctions were prepared by the method of chemical and electrochemical deposition from solution in a uniform work cycle. The open-circuit photovoltage (Uoc), short circuit-current density (Iscc) and efficiency of the Al/p-CdS/n-CdS/Zn0.6Cd0.4S heterojunctions were 650 mV; 35 mA/cm2 and 11%, accordingly. The I-U fill factor was 0.68. The value of Uoc increases and Iscc decreases by increasing of Zn in Zn1-xCdxS material

Diversifying focused testing for unit testing

Software changes constantly because developers add new features or modifications. This directly affects the effectiveness of the testsuite associated with that software, especially when these new modifications are in a specific area that no test case covers. This paper tackles the problem of generating a high quality test suite to cover repeatedly a given point in a program, with the ultimate goal of exposing faults possibly affecting the given program point. Both search based software testing and constraint solving offer ready, but low quality, solutions to this: ideally a maximally diverse covering test set is required whereas search and constraint solving tend to generate test sets with biased distributions. Our approach, Diversified Focused Testing (DFT), uses a search strategy inspired by GödelTest. We artificially inject parameters into the code branching conditions and use a bi-objective search algorithm to find diverse inputs by perturbing the injected parameters, while keeping the path conditions still satisfiable. Our results demonstrate that our technique, DFT, is able to cover a desired point in the code at least 90% of the time. Moreover, adding diversity improves the bug detection and the mutation killing abilities of the test suites. We show that DFT achieves better results than focused testing, symbolic execution and random testing by achieving from 3% to 70% improvement in mutation score and up to 100% improvement in fault detection across 105 software subjects

Nanostructured Cu2ZnSnS4 Thin Films on Porous-Si Wafer

 Nanostructure CZTS thin film was fabricated by electrodeposition technique. To manufacture the heterojunctions, p-type c-Si wafers of (100) orientation were used as a substrate.  Before anodization, the surface of the c-Si substrates were etched in an aqueous solution of HF and further washed in distilled water (at temperature of 80°С and ethyl alcohol and then dried in air. The current-voltage characteristics of the CZTS /PS solar cell under dark conditions show that forward bias current variation approximately exponentially with voltage bias. The capacitance for Nano- CZTS /PS Solar Cell decreases with the increase of the reverse bias voltage and with the increasing of etching time of nPS layers. That heterojunctions demonstrate good photo-response in the wavelength range of 510 - 650 nm

Statut juridique de la mer Caspienne

The thesis work is devoted to a topical issue - the legal status of the Caspian Sea. Currently, the political, economic, energy problems as well as environmental problems of this reservoir require urgent solutions. This work is a review, in the light of contemporary data, of the international legal status of the Caspian Sea and takes into account the analysis of the proposals of the Caspian States (States that besiege) as well as the implications of adopting one or another variant of the legal status of the Caspian Sea. The subject of the study is the Convention on the Legal Status of the Caspian Sea, as well as bilateral international treaties between the Caspian States affecting the legal regime of the Caspian Sea prior to the conclusion of a convention governing the legal status of the Caspian basin. In addition, the field of interest of this work includes acts of the national legal level regulating the protection and use of the resources of the Caspian Sea.Le travail de thèse est consacré à une question d'actualité - le statut juridique de la mer Caspienne. Actuellement, les problèmes politiques, économiques, énergétiques et environnementaux de ce réservoir nécessitent des solutions urgentes. Ce travail est un examen, à l’aune des données contemporaines, du statut juridique international de la mer Caspienne et prend en compte l’analyse des propositions des États Caspiens ainsi que les implications de l'adoption d’une ou d'une autre variante du statut juridique de la mer Caspienne. Le sujet de l'étude est la Convention sur le statut juridique de la mer Caspienne, ainsi que les traités internationaux bilatéraux entre les États de la Caspienne affectant le régime juridique de la mer Caspienne avant la conclusion d'une convention régissant le statut juridique du bassin de la Caspienne. En outre, le champ d’intérêt de ce travail comprend des actes du niveau juridique national réglementant la protection et l’utilisation des ressources de la mer Caspienne

Statut juridique de la mer Caspienne

The thesis work is devoted to a topical issue - the legal status of the Caspian Sea. Currently, the political, economic, energy problems as well as environmental problems of this reservoir require urgent solutions. This work is a review, in the light of contemporary data, of the international legal status of the Caspian Sea and takes into account the analysis of the proposals of the Caspian States (States that besiege) as well as the implications of adopting one or another variant of the legal status of the Caspian Sea. The subject of the study is the Convention on the Legal Status of the Caspian Sea, as well as bilateral international treaties between the Caspian States affecting the legal regime of the Caspian Sea prior to the conclusion of a convention governing the legal status of the Caspian basin. In addition, the field of interest of this work includes acts of the national legal level regulating the protection and use of the resources of the Caspian Sea.Le travail de thèse est consacré à une question d'actualité - le statut juridique de la mer Caspienne. Actuellement, les problèmes politiques, économiques, énergétiques et environnementaux de ce réservoir nécessitent des solutions urgentes. Ce travail est un examen, à l’aune des données contemporaines, du statut juridique international de la mer Caspienne et prend en compte l’analyse des propositions des États Caspiens ainsi que les implications de l'adoption d’une ou d'une autre variante du statut juridique de la mer Caspienne. Le sujet de l'étude est la Convention sur le statut juridique de la mer Caspienne, ainsi que les traités internationaux bilatéraux entre les États de la Caspienne affectant le régime juridique de la mer Caspienne avant la conclusion d'une convention régissant le statut juridique du bassin de la Caspienne. En outre, le champ d’intérêt de ce travail comprend des actes du niveau juridique national réglementant la protection et l’utilisation des ressources de la mer Caspienne