The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Laurie Williams - One of the best experts on this subject based on the ideXlab platform.
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on the effectiveness of unit test automation at microsoft
International Symposium on Software Reliability Engineering, 2009Co-Authors: Laurie Williams, Gunnar Kudrjavets, Nachiappan NagappanAbstract:Instituting an automated unit testing practice across a large software development team can be technically challenging and time consuming. As a result, teams may question the economic value of instituting such a practice. One large Microsoft team consisting of 32 developers transitioned from ad hoc and individualized unit testing practices to the utilization of the NUnit automated unit testing framework by all members of the team. These automated unit tests were typically written by developers after they completed coding functionality, approximately every two to three days. After a period of one year of utilizing this automated unit testing practice on Version 2 of a product, the team realized a 20.9% decrease in test defects at a cost of approximately 30% more development time relative to Version 1 of the product. The product also had a relative decrease in defects found by customers during the first two years of field use. Comparatively, other industrial teams have experienced larger decreases in defects when automated unit tests are written iteratively, as is done with the test driven development practice, for a similar time increase. These results indicate automated unit testing is beneficial but additional quality improvements may be realized if the tests are written iteratively.
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Realizing quality improvement through test driven development: results and experiences of four industrial teams
Empirical Software Engineering, 2008Co-Authors: Nachiappan Nagappan, E. Michael Maximilien, Thirumalesh Bhat, Laurie WilliamsAbstract:test-driven development (TDD) is a software development practice that has been used sporadically for decades. With this practice, a software engineer cycles minute-by-minute between writing failing unit tests and writing implementation code to pass those tests. test-driven development has recently re-emerged as a critical enabling practice of agile software development methodologies. However, little empirical evidence supports or refutes the utility of this practice in an industrial context. Case studies were conducted with three development teams at Microsoft and one at IBM that have adopted TDD. The results of the case studies indicate that the pre-release defect density of the four products decreased between 40% and 90% relative to similar projects that did not use the TDD practice. Subjectively, the teams experienced a 15–35% increase in initial development time after adopting TDD.
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on the sustained use of a test driven development practice at ibm
Agile Conference, 2007Co-Authors: J C Sanchez, Laurie Williams, E.m. MaximilienAbstract:test-driven development (TDD) is an agile practice that is widely accepted and advocated by most agile methods and methodologists. In this paper, we report on a post hoc analysis of the results of an IBM team who has sustained use of TDD for five years and over ten releases of a Java-implemented product. The team worked from a design and wrote tests incrementally before or while they wrote code and, in the process, developed a significant asset of automated tests. The IBM team realized sustained quality improvement relative to a pre-TDD project and consistently had defect density below industry standards. As a result, our data indicate that the TDD practice can aid in the production of high quality products. This quality improvement would compensate for the moderate perceived productivity losses. Additionally, our data indicates that the use of TDD may decrease the degree to which code complexity increases as software ages, as measured by cyclomatic complexity metric.
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a structured experiment of test driven development
Information & Software Technology, 2004Co-Authors: Boby George, Laurie WilliamsAbstract:Abstract Test Driven development (TDD) is a software development practice in which unit test cases are incrementally written prior to code implementation. We ran a set of structured experiments with 24 professional pair programmers. One group developed a small Java program using TDD while the other (control group), used a waterfall-like approach. Experimental results, subject to external validity concerns, tend to indicate that TDD programmers produce higher quality code because they passed 18% more functional black-box test cases. However, the TDD programmers took 16% more time. Statistical analysis of the results showed that a moderate statistical correlation existed between time spent and the resulting quality. Lastly, the programmers in the control group often did not write the required automated test cases after completing their code. Hence it could be perceived that waterfall-like approaches do not encourage adequate testing. This intuitive observation supports the perception that TDD has the potential for increasing the level of unit testing in the software industry.
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assessing test driven development at ibm
International Conference on Software Engineering, 2003Co-Authors: Michael E Maximilien, Laurie WilliamsAbstract:In a software development group of IBM Retail Store Solutions, we built a non-trivial software system based on a stable standard specification using a disciplined, rigorous unit testing and build approach based on the test- driven development (TDD) practice. Using this practice, we reduced our defect rate by about 50 percent compared to a similar system that was built using an ad-hoc unit testing approach. The project completed on time with minimal development productivity impact. Additionally, the suite of automated unit test cases created via TDD is a reusable and extendable asset that will continue to improve quality over the lifetime of the software system. The test suite will be the basis for quality checks and will serve as a quality contract between all members of the team.
Hossein Saiedian - One of the best experts on this subject based on the ideXlab platform.
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test driven learning in early programming courses
Technical Symposium on Computer Science Education, 2008Co-Authors: David S. Janzen, Hossein SaiedianAbstract:Coercing new programmers to adopt disciplined development practices such as thorough unit testing is a challenging endeavor. test-driven development (TDD) has been proposed as a solution to improve both software design and testing. test-driven learning (TDL) has been proposed as a pedagogical approach for teaching TDD without imposing significant additional instruction time. This research evaluates the effects of students using a test-first (TDD) versus test-last approach in early programming courses, and considers the use of TDL on a limited basis in CS1 and CS2. Software testing, programmer productivity, programmer performance, and programmer opinions are compared between test-first and test-last programming groups. Results from this research indicate that a test-first approach can increase student testing and programmer performance, but that early programmers are very reluctant to adopt a test-first approach, even after having positive experiences using TDD. Further, this research demonstrates that TDL can be applied in CS1/2, but suggests that a more pervasive implementation of TDL may be necessary to motivate and establish disciplined testing practice among early programmers.
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does test driven development really improve software design quality
IEEE Software, 2008Co-Authors: David S. Janzen, Hossein SaiedianAbstract:Support for test-driven development [TDD] is growing in many development contexts beyond its common association with extreme programming. By focusing on how TDD influences design characteristics, we hope to raise awareness of TDD as a design approach and assist others in decisions on whether and how to adopt TDD. Our results indicate that test-first programmers are more likely to write software in more and smaller units that are less complex and more highly tested. We weren't able to confirm claims that TDD improves cohesion while lowering coupling, but we anticipate ways to clarify the questions these design characteristics raised. In particular, we're working to eliminate the confounding factor of accessor usage in the cohesion metrics.
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on the influence of test driven development on software design
Conference on Software Engineering Education and Training, 2006Co-Authors: David S. Janzen, Hossein SaiedianAbstract:test-driven development (TDD) is an agile software development strategy that addresses both design and testing. This paper describes a controlled experiment that examines the effects of TDD on internal software design quality. The experiment was conducted with undergraduate students in a software engineering course. Students in three groups completed semester-long programming projects using either an iterative Test-First (TDD), iterative Test-Last, or linear Test-Last approach. Results from this study indicate that TDD can be an effective software design approach improving both code-centric aspects such as object decomposition, test coverage, and external quality, and developer-centric aspects including productivity and confidence. In addition, iterative development approaches that include automated testing demonstrated benefits over a more traditional linear approach with manual tests. This study demonstrates the viability of teaching TDD with minimal effort in the context of a relatively traditional development approach. Potential dangers with TDD are identified regarding programmer motivation and discipline. Pedagogical implications and instructional techniques which may foster TDD adoption will also be referenced.
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test driven learning intrinsic integration of testing into the cs se curriculum
Technical Symposium on Computer Science Education, 2006Co-Authors: David S. Janzen, Hossein SaiedianAbstract:test-driven learning (TDL) is an approach to teaching computer programming that involves introducing and exploring new concepts through automated unit tests. TDL offers the potential of teaching testing for free, of improving programmer comprehension and ability, and of improving software quality both in terms of design quality and reduced defect density.This paper introduces test-driven learning as a pedagogical tool. It will provide examples of how TDL can be incorporated at multiple levels in computer science and software engineering curriculum for beginning through professional programmers. In addition, the relationships between TDL and test-driven development will be explored.Initial evidence indicates that TDL can improve student comprehension of new concepts while improving their testing skills with no additional instruction time. In addition, by learning to construct programs in a test-driven manner, students are expected to be more likely to develop their own code with a test-driven approach, likely resulting in improved software designs and quality.
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test driven development concepts taxonomy and future direction
IEEE Computer, 2005Co-Authors: David S. Janzen, Hossein SaiedianAbstract:test-driven development creates software in very short iterations with minimal upfront design. This strategy requires writing automated tests prior to developing functional code in small, rapid iterations. Although developers have been applying TDD in various forms for several decades, this software development strategy has continued to gain increased attention as one of the core extreme programming practices.
David S. Janzen - One of the best experts on this subject based on the ideXlab platform.
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a survey of evidence for test driven development in academia
Technical Symposium on Computer Science Education, 2008Co-Authors: Chetan Desai, David S. Janzen, Kyle SavageAbstract:University professors traditionally struggle to incorporate software testing into their course curriculum. Worries include double-grading for correctness of both source and test code and finding time to teach testing as a topic. test-driven development (TDD) has been suggested as a possible solution to improve student software testing skills and to realize the benefits of testing. According to most existing studies, TDD improves software quality and student productivity. This paper surveys the current state of TDD experiments conducted exclusively at universities. Similar surveys compare experiments in both the classroom and industry, but none have focused strictly on academia.
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test driven learning in early programming courses
Technical Symposium on Computer Science Education, 2008Co-Authors: David S. Janzen, Hossein SaiedianAbstract:Coercing new programmers to adopt disciplined development practices such as thorough unit testing is a challenging endeavor. test-driven development (TDD) has been proposed as a solution to improve both software design and testing. test-driven learning (TDL) has been proposed as a pedagogical approach for teaching TDD without imposing significant additional instruction time. This research evaluates the effects of students using a test-first (TDD) versus test-last approach in early programming courses, and considers the use of TDL on a limited basis in CS1 and CS2. Software testing, programmer productivity, programmer performance, and programmer opinions are compared between test-first and test-last programming groups. Results from this research indicate that a test-first approach can increase student testing and programmer performance, but that early programmers are very reluctant to adopt a test-first approach, even after having positive experiences using TDD. Further, this research demonstrates that TDL can be applied in CS1/2, but suggests that a more pervasive implementation of TDL may be necessary to motivate and establish disciplined testing practice among early programmers.
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does test driven development really improve software design quality
IEEE Software, 2008Co-Authors: David S. Janzen, Hossein SaiedianAbstract:Support for test-driven development [TDD] is growing in many development contexts beyond its common association with extreme programming. By focusing on how TDD influences design characteristics, we hope to raise awareness of TDD as a design approach and assist others in decisions on whether and how to adopt TDD. Our results indicate that test-first programmers are more likely to write software in more and smaller units that are less complex and more highly tested. We weren't able to confirm claims that TDD improves cohesion while lowering coupling, but we anticipate ways to clarify the questions these design characteristics raised. In particular, we're working to eliminate the confounding factor of accessor usage in the cohesion metrics.
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on the influence of test driven development on software design
Conference on Software Engineering Education and Training, 2006Co-Authors: David S. Janzen, Hossein SaiedianAbstract:test-driven development (TDD) is an agile software development strategy that addresses both design and testing. This paper describes a controlled experiment that examines the effects of TDD on internal software design quality. The experiment was conducted with undergraduate students in a software engineering course. Students in three groups completed semester-long programming projects using either an iterative Test-First (TDD), iterative Test-Last, or linear Test-Last approach. Results from this study indicate that TDD can be an effective software design approach improving both code-centric aspects such as object decomposition, test coverage, and external quality, and developer-centric aspects including productivity and confidence. In addition, iterative development approaches that include automated testing demonstrated benefits over a more traditional linear approach with manual tests. This study demonstrates the viability of teaching TDD with minimal effort in the context of a relatively traditional development approach. Potential dangers with TDD are identified regarding programmer motivation and discipline. Pedagogical implications and instructional techniques which may foster TDD adoption will also be referenced.
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test driven learning intrinsic integration of testing into the cs se curriculum
Technical Symposium on Computer Science Education, 2006Co-Authors: David S. Janzen, Hossein SaiedianAbstract:test-driven learning (TDL) is an approach to teaching computer programming that involves introducing and exploring new concepts through automated unit tests. TDL offers the potential of teaching testing for free, of improving programmer comprehension and ability, and of improving software quality both in terms of design quality and reduced defect density.This paper introduces test-driven learning as a pedagogical tool. It will provide examples of how TDL can be incorporated at multiple levels in computer science and software engineering curriculum for beginning through professional programmers. In addition, the relationships between TDL and test-driven development will be explored.Initial evidence indicates that TDL can improve student comprehension of new concepts while improving their testing skills with no additional instruction time. In addition, by learning to construct programs in a test-driven manner, students are expected to be more likely to develop their own code with a test-driven approach, likely resulting in improved software designs and quality.
Nachiappan Nagappan - One of the best experts on this subject based on the ideXlab platform.
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on the effectiveness of unit test automation at microsoft
International Symposium on Software Reliability Engineering, 2009Co-Authors: Laurie Williams, Gunnar Kudrjavets, Nachiappan NagappanAbstract:Instituting an automated unit testing practice across a large software development team can be technically challenging and time consuming. As a result, teams may question the economic value of instituting such a practice. One large Microsoft team consisting of 32 developers transitioned from ad hoc and individualized unit testing practices to the utilization of the NUnit automated unit testing framework by all members of the team. These automated unit tests were typically written by developers after they completed coding functionality, approximately every two to three days. After a period of one year of utilizing this automated unit testing practice on Version 2 of a product, the team realized a 20.9% decrease in test defects at a cost of approximately 30% more development time relative to Version 1 of the product. The product also had a relative decrease in defects found by customers during the first two years of field use. Comparatively, other industrial teams have experienced larger decreases in defects when automated unit tests are written iteratively, as is done with the test driven development practice, for a similar time increase. These results indicate automated unit testing is beneficial but additional quality improvements may be realized if the tests are written iteratively.
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Realizing quality improvement through test driven development: results and experiences of four industrial teams
Empirical Software Engineering, 2008Co-Authors: Nachiappan Nagappan, E. Michael Maximilien, Thirumalesh Bhat, Laurie WilliamsAbstract:test-driven development (TDD) is a software development practice that has been used sporadically for decades. With this practice, a software engineer cycles minute-by-minute between writing failing unit tests and writing implementation code to pass those tests. test-driven development has recently re-emerged as a critical enabling practice of agile software development methodologies. However, little empirical evidence supports or refutes the utility of this practice in an industrial context. Case studies were conducted with three development teams at Microsoft and one at IBM that have adopted TDD. The results of the case studies indicate that the pre-release defect density of the four products decreased between 40% and 90% relative to similar projects that did not use the TDD practice. Subjectively, the teams experienced a 15–35% increase in initial development time after adopting TDD.
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evaluating the efficacy of test driven development industrial case studies
International Symposium on Empirical Software Engineering, 2006Co-Authors: Thirumalesh Bhat, Nachiappan NagappanAbstract:This paper discusses software development using the Test Driven development (TDD) methodology in two different environments (Windows and MSN divisions) at Microsoft. In both these case studies we measure the various context, product and outcome measures to compare and evaluate the efficacy of TDD. We observed a significant increase in quality of the code (greater than two times) for projects developed using TDD compared to similar projects developed in the same organization in a non-TDD fashion. The projects also took at least 15% extra upfront time for writing the tests. Additionally, the unit tests have served as auto documentation for the code when libraries/APIs had to be used as well as for code maintenance.
Eisenhut Wolfgang - One of the best experts on this subject based on the ideXlab platform.
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Anwendung der Clean Code Prinzipien an Webanwendungen
2020Co-Authors: Eisenhut WolfgangAbstract:Diese Arbeit beschreibt am Fallbeispiel MicroLearning das Refactoring einer bestehenden Progressive Web App gemäß den Clean Code und SOLID Prinzipien von Robert Cecil Martin mit nachfolgender Implementierung von Sicherheitsvorkehrungen gemäß der Test Driven development Prinzipien. Die Umstellung der Software Entwicklung auf TDD, bei einer bestehenden Web-Anwendung, ist Ziel der Arbeit Die Grundlagen zu Micro-learning, einem Begriff aus den Bildungswissenschaften, die Clean Code Prinzipien sowie das SOLID Prinzip und Basiswissen zu Test Driven development ebenso wie ausgewählte Grundlagen zur Websicherheit werden in den Grundlagen vorgestellt. Micro-learning ist der inhaltliche Kern der bestehenden Webanwendung, die Geschäftslogik. Die Clean Code Prinzipien und SOLID Prinzipien sind die Basis für das angestrebte Refactoring. Durch Anwendung von Clean Code und SOLID Prinzipien wird eine Clean Architecture erzeugt. Weiters werden einige Bedrohungen und Sicherheitsvorkehrungen für Webanwendungen präsentiert. Diese Sicherheitsmaßnahmen sind das Fundament der geplanten Implementierung nach Test Driven development Richtlinien. Das Thema der Implementierung wurde willkürlich gewählt und dient als Mittel zum Zweck. Anhand des Fallbeispieles wird die Webapplikation auf die Abweichungen zu den Clean Architecture, Clean Code und Solid Prinzipien untersucht. Die gefundenen Abweichungen werden für ein nachfolgendes Refactoring vorgeschlagen. Weiters wird untersucht, inwieweit sich Sicherheitsmaßnahmen gegen die vorgestellten Bedrohungen für die Webanwendung MicroLearnig ableiten lassen. Die Sicherheitsmaßnahmen werden für die geplante Implementierung vorgeschlagen. Basierend auf den Grundlagen, wird eine Hypothese erarbeitet, die einen allgemeinen Weg für schon implementierte Webanwendungen aufzeigt, um auf TDD umzusteigen. Die Fallstudie erzeugt eine Hypothese, die in der Conclusio präsentiert wird. Nach einem erfolgreichen Refactoring an einer Webanwendung, dessen Ziel eine Clean Architecture ist, wird eine anschließende Implementierung von Sicherheitsmaßnahmen, gemäß Test Driven development Richtlinien, ohne Änderungen an der Software Architektur, möglich.This thesis describes the refactoring of an existing progressive web app using MicroLearning as an case study and following the principles of clean code and SOLID by Robert Cecil Martin as well as the implementation of safety precautions following the Test Driven development principles. Switching the software development process to TDD on an existing web app is the goal of this thesis. The fundamentals of Micro-learning, a term used in educational sciences, the clean code principles, the SOLID principle, the basic knowledge of test driven development as well as selected basics of web security are presented in the fundamentals. Micro-learning is the core content of the existing web app, the business logic. Clean code and SOLID principles are the basics for the aspired refactoring. By using these principles a clean architecture will be achieved. Furthermore threats and security measures for web apps are presented. These security measures are the foundation of the planned implementation following the Test Driven development guidelines. The subject of the implementation was chosen arbitrary and is the means to an end. Using the case study the web app gets reviewed to determine differences to the Clean Architecture, Clean Code and SOLID Principles. Any differences found are recommended for a following refactoring. Furthermore security measures for the presented threats of the web app MicroLearning get reviewed. Those security measures are recommended for further implementation. Based on the fundamentals a hypothesis is formed, that shows a universal way to switch development to TDD on an already implemented web app. The case study creates a hypothesis, which is presented in the conclusion. After a successful refactoring of an web app, which aims for a Clean Architecture, subsequent implementation of security measures following TDD guidelines becomes possible without changes in the software architecture
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Anwendung der Clean Code Prinzipien an Webanwendungen : (Fallstudie MircoLearning)
2020Co-Authors: Eisenhut WolfgangAbstract:Die Umstellung einer bestehenden und traditionell entwickelten Webanwendung MicroLearning (ML) auf Test Driven development (TDD) ist Ziel der Arbeit. In der vorliegenden Fallstudie wird mit Hilfe eines Experimentes die nachfolgende Hypothese überprüft. Hypothese: Entspricht eine bestehenden Webanwendung den Clean Architecture Prinzipien, ist eine Implementierung von Sicherheitsmaßnahmen nach TDD Prinzipien, ohne Änderung der Software Architektur möglich. Refaktorierungskandidaten und die Sicherheitsmaßnahmen werden auf drei verschiedene Varianten implementiert. Bei der ersten Variante erfolgt die Implementierung ohne Unit Tests. Bei der zweiten Variante wird zuerst der Code geschrieben und danach die Unit Tests verfasst. Bei der dritten Variante erfolgt die Implementierung nach TDD Prinzipien. Dabei wird die Qualität des Codes für jede Variante gemessen, um eine Verbesserung oder Verschlechterung der Softwarequalität zu ermitteln. Die Qualität wird einerseits mit einem SonarQube Server und andererseits mit Visual Studio Werkzeugen gemessen. Im theoretischen Teil werden Grundlagen zur Bestimmung der Codequalität und Unit Tests vorgestellt. Die Ergebnisse bestätigen die Hypothese für ML. Die Software Qualität hat sich in allen drei Varianten durch die Implementierung der Refaktorierungskandidaten partiell verbessert.The goal of this thesis is the conversion of an existing and traditionally developed web application MicroLearning (ML) to Test Driven development (TDD). In the present case study, the following hypothesis is tested using an experiment. Hypothesis: If an existing web application complies with the Clean Architecture principles, security measures can be implemented according to TDD principles without changing the software architecture. Refactoring candidates and security measures are implemented in three different ways. The first variant is implemented without unit tests. In the second variant, the code is written first and afterwards the unit tests are created. The third variant is implemented according to TDD principles. The quality of the code for each variant is measured in order to determine whether the software quality has improved or deteriorated. The quality is measured on the one hand with a SonarQube server and on the other hand with Visual Studio tools. The theoretical part presents the basics for determining code quality and unit tests. The results confirm the hypothesis for ML. The software quality has partially improved in all three variants by implementing the refactor candidates
