Section: New Results

Software Quality: Testing and Tools

Testing Habits. What are the Testing Habits of Developers? We conducted a case study in a large IT company. Tests are considered important to ensure the good behavior of applications and improve their quality. But development in companies also involves tight schedules, old habits, less-trained developers, or practical difficulties such as creating a test database. As a result, good testing practices are not always used as often as one might wish. With a major IT company, we are engaged in a project to understand developers testing behavior, and whether it can be improved. Some ideas are to promote testing by reducing test session length, or by running automatically tests behind the scene and send warnings to developers about the failing ones. Reports on developers testing habits in the literature focus on highly distributed open-source projects, or involve students programmers. As such they might not apply to our industrial, closed source, context. We take inspiration from experiments of two papers of the literature to enhance our comprehension of the industrial environment. We report the results of a field study on how often the developers use tests in their daily practice, whether they make use of tests selection and why they do. Results are reinforced by interviews with developers involved in the study. The main findings are that test practice is in better shape than we expected; developers select tests ruthlessly (instead of launching an entire test suite); although they are not accurate in their selection, and; contrary to expectation, test selection is not influenced by the size of the test suite nor the duration of the tests. [23]

Tests in Open-Source. During the development, it is known that tests ensure the good behavior of applications and improve their quality. We studied developers testing behavior inside the Pharo community in the purpose to improve it. We report results of a field study on how often the developers use tests in their daily practice, whether they make use of tests selection and why they do. Results are strengthened by interviews with developers involved in the study. The main findings are that developers run tests every modifications of their code they did; most of the time they practice test selection (instead of launching an entire test suite); however they are not accurate in their selection; they change their selection depending on the duration of the tests and; contrary to expectation, test selection is not influenced by the size of the test suite. [35]

CodeCritics Applied to Database Schema: Challenges and First Results. Relational databases (DB) play a critical role in many information systems. For different reasons, their schemas gather not only tables and columns but also views, triggers or stored functions (i.e., fragments of code describing treatments). As for any other code-related artefact, software quality in a DB schema helps avoiding future bugs. However, few tools exist to analyze DB quality and prevent the introduction of technical debt. We present research issues related to assessing the software quality of a DB schema by adapting existing source code analysis research to database schemas. We present preliminary results that have been validated through the implementation of DBCritics, a prototype tool to perform static analysis on the SQL source code of a database schema. DBCritics addresses the limitations of existing DB quality tools based on an internal representation considering all entities of the database and their relationships. [26]

Recommending Source Code Locations for System Specific Transformations. From time to time, developers perform sequences of code transformations in a systematic and repetitive way. This may happen, for example, when introducing a design pattern in a legacy system: similar classes have to be introduced, containing similar methods that are called in a similar way. Automation of these sequences of transformations has been proposed in the literature to avoid errors due to their repetitive nature. However, developers still need support to identify all the relevant code locations that are candidate for transformation. Past research showed that these kinds of transformation can lag for years with forgotten instances popping out from time to time as other evolutions bring them into light. We evaluate three distinct code search approaches (structural, based on Information Retrieval, and AST based algorithm) to find code locations that would require similar transformations. We validate the resulting candidate locations from these approaches on real cases identified previously in literature. The results show that looking for code with similar roles, e.g., classes in the same hierarchy, provides interesting results with an average recall of 87% and in some cases the precision up to 70%. [33]

Quality-oriented Move Method Refactoring. Restructuring is an important activity to improve software internal structure. Even though there are many restructuring approaches, very few consider the refactoring impact on the software quality. In this paper, we propose an semi-automatic software restructuring approach based on quality attributes. We rely on the measurements of the Quality Model for Object Oriented Design (QMOOD) to recommend Move Method refactorings that improve software quality. In our preliminary evaluation on three open-source systems, our approach achieved an average recall of 57%. [34]