Articles

Nuno Santos is currently a Senior Business Analyst at Natixis Portugal. He holds a PhD in Technologies and Information Systems, and is also certified from Agile Alliance as CSPO, and from the IIBA as CCBA, AAC and POA. He has also written articles about requirements, agility and product ownership at RE Magazine, BA Digest, Analyst Catalyst, Medium, and in several scientific conferences.

• Requirements Elicitation in Modern Product Discovery
• Inputs to requirements engineering in agile projects

Prof. Dr. Salinesi is an active academic who teaches topics in relation with software design such as Requirements Engineering, and Software Product Lines. He was involved in many funded research projects (FP4, FP5, H2020, ANR) and was the leader for collaborations and consultancy works for various companies such as France Télécom, SNCF, Renault, EDF or REXEL). He has been General Chair of SPLC, CAiSE, REFSQ international conferences, and was Organizing Chair of the 13th IEEE International Conference on Requirements Engineering.

At IREB, Prof Salinesi has acted for 2 mandates as Second Chair of the Executive Committee. He is now Full Member, member of the Editorial Board, and WG Member.

• Conversation with an Artificial Intelligence

Gil Regev has been a researcher at EPFL since 1997 in the fields of enterprise information systems, requirements engineering, change management and knowledge management. Since 2008 he is also manager and consultant at Itecor, a boutique consultancy firm. Previously Gil developed software for computer peripherals at Logitech, in Switzerland and California.

• A General Systems Thinking Perspective on the CPRE

Alain Wegmann is a full professor at the School of Computer and Communication Sciences, EPFL, Switzerland. He worked 14 years for Logitech (Switzerland, Taiwan, US) in positions ranging from software developer, IS manager, manufacturing engineering to VP of engineering and OEM marketing before joining the EPFL in 1997. His teaching, consulting and research are in the fields of enterprise architecture, requirements engineering and service engineering.

• A General Systems Thinking Perspective on the CPRE

Olivier Hayard has been a consultant and in charge of IT and Knowledge Management at Itecor, a boutique consultancy firm, since 1993. Olivier’s main interests are business analysis and requirements management, as practitioner, trainer and researcher.

• A General Systems Thinking Perspective on the CPRE

Project manager since 2008, certified Scrum Product Owner, Agile Project Manager, with foundations of PRINCE2. Over six years of experience as a UX designer and researcher. Worked in digital agencies as a digital project manager, then switched to the client's side. Head of Product in iTaxi, then in Pergamin (e-signature). Worked also for libraries and museums in Poland to help improve the accessibility of digital products.

Awarded by Innovation Ad Award for the prototype for Sensodyne and by nomination in Mobile Trends for the mobile app for drivers. An author of articles about product management, user experience, and accessibility.

• The Potential of User Tests for Requirements Engineering

Freelance trainer and consultant in Software Engineering. 20 years of work experience, including 7 years as consultant and project manager, 10 years in research and university teaching, and two guest professorships. Associate member at IREB, co-author of syllabus and handbook for the CPRE Advanced Level in Requirements Management. www.herrmann-ehrlich.de

• Requirements Engineering in Job Offers

Maya Daneva, PhD, is Senior Member of Scientific Staff in the Services and Cybersecurity group at the University of Twente, the Netherlands. Her research interests are requirements engineering for large systems, security requirements engineering, requirements-based project estimation, user feedback analytics, and empirical research methods. Maya has a strong international exposure having spent two years of her career in Germany at the University of Saarbruecken and in the IDS Scheer, and 9 years as a business process analyst for SAP Enterprise Recourse Planning projects at TELUS Corporation, Canada’s second largest telecommunication company.

• Requirements Engineering in Job Offers

Chong Wang is an assistant professor at Wuhan University. She has over 10 years of work experience in research and university teaching. Her research interests include requirements engineering, software engineering, and service computing.

• Requirements Engineering in Job Offers

Nelly Condori-Fernandez is an assistant professor at the Universidade da Coruna (Spain) and research associate of the Vrije Universiteit Amsterdam (The Netherlands). Her research focuses on topics related to quality requirements prioritization and sustainability. She has published 85 articles in indexed journals and ranked conferences. Besides, she has been involved in several European projects.

• Requirements Engineering in Job Offers

Luisa Mich is an Associate Professor of Computer Science at the University of Trento, Italy. Her research interests include requirements engineering, creativity and web strategies. She is an author of more than 150 papers.
 

• Interview with John Mylopoulos
• Requirements Elicitation (ReqElic) in My Company

Daniel Méndez is an Associate Professor for Software Engineering at the Blekinge Institute of Technology, Sweden and Senior Scientist at fortiss, the research institute of the Free State of Bavaria for software-intensive systems and services. His research is on Empirical Software Engineering with a particular focus on interdisciplinary, qualitative research in Requirements Engineering and its quality improvement. He regularly publishes in various software engineering publications and has occupied several key positions in venues of the empirical software engineering community. He is a member of the ACM, the IEEE Computer Society, and the German association of university professors and lecturers, and he serves as the representative to ISERN, the International Empirical Software Engineering Research Network. Further information is provided at www.mendezfe.org.

• What is the Relevance of Requirements Engineering Research to Practitioners?
• Modeling Requirements and Context as a means for Automated Requirements Validation

Xavier Franch is Professor at the Universitat Politècnica de Barcelona (UPC-BarcelonaTech), Spain. He is Council Member and Full Member of the IREB association. He has published over 200 peer-reviewed papers in conferences and journals, many of them related to requirements engineering. He was Program Co-Chair of the RE’16 and REFSQ’11 conferences, and he belongs to the Editorial Board of the Requirements Engineering Journal (Springer) and Information Software and Technology (IST) journals, among others. He is coordinator of the Q-Rapids project and participates in the OpenReq project, both in the H2020 programme. He organizes workshops concerning requirements engineering for NLP4RE, CrowdRE, JIT-RE and others.

• What is the Relevance of Requirements Engineering Research to Practitioners?
• Modeling Requirements and Context as a means for Automated Requirements Validation

Andreas Vogelsang is a post-doc researcher in the software & systems engineering group at the Technical University of Munich. He works on model-based requirements engineering and participated in several research collaborations with industrial partners especially from the automotive industry. His research published was published in relevant international conferences like RE, REFSQ, or ICSE.

• What is the Relevance of Requirements Engineering Research to Practitioners?
• Modeling Requirements and Context as a means for Automated Requirements Validation

Rana Siadati is currently a PhD student in Software Requirements Engineering and also a visiting lecturer by the School of Computer Science at the University of Hertfordshire. Alongside these roles, Rana has many years of academic and industrial experience, also at managerial level, gained in the UK and abroad.

• Learning from history: The case of Software Requirements Engineering

Paul Wernick is a Senior Lecturer in Computer Science at the University of Hertfordshire. Dr Wernick has taken leading roles in the ProSim series of software process simulation workshops, and the IEEE Workshop on Software Evolvability. Dr Wernick’s current research interests cover the high-level human environment within which software processes occur and their simulation, and computer security.

• Learning from history: The case of Software Requirements Engineering

Vito Veneziano is a Senior Lecturer in Computer Science at the University of Hertfordshire, and his interests range from software engineering, HCI, requirements analysis and system modelling, to how software systems impact on organisations. Previously Dr Veneziano worked in IT and project management, business application development, software design and consultancy.

• Learning from history: The case of Software Requirements Engineering

Priyank Arora is a Senior Business Analyst working in the digital IT space for 12+ years. He is a CBAP certified professional with a Core Credential in Business Analytics from Harvard Business School. He works on large scale digital transformation projects for the world’s leading travel group, where he helped to transition the requirement engineering processes from traditional to Agile working methodologies. He was also involved with a machine learning initiative within his organisation and is a data science enthusiast with an interest in applying analytical thinking and decision automation for business growth.

• Data Science – the expanding frontier for Business Analysts

Grigory Grin is a Chief Software Architect at Axinom – software supplier for Media- and In-Flight Entertainment solutions based in Germany and Estonia.
Grigory studied mathematics and graduated from the Ural State University in Russia in 1995. During his 25 years career on the software development field, Grigory had responsibilities in a broad range of roles – Development, Architecture, Business Analysis, Project Management. His main strengths are in alignment between the customer needs and contractors technical capabilities and solution portfolio to deliver the highest business value.
As a practitioner, Grigory has successfully led multiple multi-million euro projects for world-known brands in the aerospace industry with significant challenges on the field of Requirements Engineering.

• When the rubber hits the road

Jason Hansen obtained a BS in Chemical Engineering from Michigan Tech. He left the work force in 2005 to focus on raising an adopted special needs daughter. In 2015, he decided to return to school and obtained his AAAS in Network Admin. He is working as a tutor at GRCC while pursuing a Master’s Degree in Computer Software Engineering at GVSU.

• Challenges in the elicitation and determination of precise requirements from animal stakeholders

Hans van Loenhoud MSc is a consultant and teacher at Taraxacum in the Netherlands. He has been working in software development for more than 35 years, starting as a Cobol programmer and later on specialized in test and quality management.
In this role, he has been teaching various ISTQB test courses and has been chair of TestNet, the Dutch association of professional software testers. In recent years, he joined IREB to build a bridge between software testing and requirements engineering. He gives various Business Analysis, Requirements Engineering and Software Testing trainings. Hans is also a lecturer at the Amsterdam University of Applied Sciences for these topics and participates in the IREB advanced level Elicitation working group.

• On the right track
• The goal is to solve the problem
• Translating Exam Questions

Hans van Loenhoud MSc is a consultant and teacher at Taraxacum in the Netherlands. He has been working in software development for more than 35 years, starting as a Cobol programmer and later on specialized in test and quality management.
In this role, he has been teaching various ISTQB test courses and has been chair of TestNet, the Dutch association of professional software testers. In recent years, he joined IREB to build a bridge between software testing and requirements engineering. He gives various Business Analysis, Requirements Engineering and Software Testing trainings. Hans is also a lecturer at the Amsterdam University of Applied Sciences for these topics and participates in the IREB advanced level Elicitation working group.

• The goal is to solve the problem

Dr. Kim Lauenroth is Chief Requirements Engineer and leads a competence centre for requirements engineering at adesso AG.

He has over 10 years of experience in software and requirements engineering in different domains. He regularly speaks at internal conferences in the topic of RE. Within IREB, he is involved in the development of the advanced level module Elicitation & Consolidation.

Kim received his PhD in the field of requirements engineering from the University of Duisburg-Essen and studied computer science, business administration and psychology at the University of Dortmund.

• The goal is to solve the problem

Dr. Patrick Steiger, based in Switzerland, leads the requirements engineering activities of Infometis AG and is a part-time teacher at the MAS HCID (Human-Computer Interaction Design) which is provided as a cooperation of University of Basle and HSR Hochschule für Technik Rapperswil.
Since more than 20 years he works as a consultant in software engineering projects, focusing on requirements engineering. His PhD was on the topic of “Personal Risk Management”, which already at that time addressed problems and goals of individuals.

• The goal is to solve the problem

Karol Frühauf is co-founder of INFOGEM AG in Switzerland, since 1987 consulting in the field of software project and quality management (http://www.infogem.ch). He worked 12 years for BBC Brown Boveri & Cie and helped since 1987 many companies to improve their processes and products. He co-authored two books and is a frequent speaker, tutor and teacher in the field of software engineering. His main interests are test and quality management and requirements engineering.
He initiated and directs the "Bridge Guard Art / Science Residence Centre" in Štúrovo, Slovakia (http://www.bridgeguard.org).

• Sharing My Doubts on the Focus of Requirements
• Sharing My Doubts on Goals and Requirements
• Sharing My Doubts on Shall / Should / Will etc.
• Sharing My Doubts on Acceptance Criteria

Karol Frühauf is co-founder of INFOGEM AG in Switzerland, since 1987 consulting in the field of software project and quality management (http://www.infogem.ch). He worked 12 years for BBC Brown Boveri & Cie and helped since 1987 many companies to improve their processes and products. He co-authored two books and is a frequent speaker, tutor and teacher in the field of software engineering. His main interests are test and quality management and requirements engineering.
He initiated and directs the "Bridge Guard Art / Science Residence Centre" in Štúrovo, Slovakia (http://www.bridgeguard.org).

• Sharing My Doubts on the Focus of Requirements
• Sharing My Doubts on Goals and Requirements
• Sharing My Doubts on Shall / Should / Will etc.
• Sharing My Doubts on Acceptance Criteria

Karol Frühauf is co-founder of INFOGEM AG in Switzerland, since 1987 consulting in the field of software project and quality management (http://www.infogem.ch). He worked 12 years for BBC Brown Boveri & Cie and helped since 1987 many companies to improve their processes and products. He co-authored two books and is a frequent speaker, tutor and teacher in the field of software engineering. His main interests are test and quality management and requirements engineering.
He initiated and directs the "Bridge Guard Art / Science Residence Centre" in Štúrovo, Slovakia (http://www.bridgeguard.org).

• Sharing My Doubts on the Focus of Requirements
• Sharing My Doubts on Goals and Requirements
• Sharing My Doubts on Shall / Should / Will etc.
• Sharing My Doubts on Acceptance Criteria

Karol Frühauf is co-founder of INFOGEM AG in Switzerland, since 1987 consulting in the field of software project and quality management (http://www.infogem.ch). He worked 12 years for BBC Brown Boveri & Cie and helped since 1987 many companies to improve their processes and products. He co-authored two books and is a frequent speaker, tutor and teacher in the field of software engineering. His main interests are test and quality management and requirements engineering.
He initiated and directs the "Bridge Guard Art / Science Residence Centre" in Štúrovo, Slovakia (http://www.bridgeguard.org).

• Sharing My Doubts on the Focus of Requirements
• Sharing My Doubts on Goals and Requirements
• Sharing My Doubts on Shall / Should / Will etc.
• Sharing My Doubts on Acceptance Criteria

Bastian Tenbergen is an Assistant Professor for Computer Science at the State University of New York at Oswego. He has co-authored articles and contributed to several books in the area of Software Engineering. Bastian’s main research focus is on Model-Based Requirements Engineering, Context Analysis, and Safety of Embedded and Cyber-Physical Systems. He has many years of project and consulting experience and has worked closely with industry.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Andreas Vogelsang is a post-doc researcher in the software & systems engineering group at the Technical University of Munich. He works on model-based requirements engineering and participated in several research collaborations with industrial partners especially from the automotive industry. His research published was published in relevant international conferences like RE, REFSQ, or ICSE.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Thorsten Weyer is a research group leader at the University of Duisburg-Essen. He has been a member of organization committees, program committees and reviewer for scientific conferences and journals. Thorsten gives regular lectures at the University and is an experienced conference speaker. He has also held several leading positions in research projects and technology transfer projects. He is member of the IREB council and head of the IREB working group Requirements Modeling.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Andreas Froese works as a research assistant in the working group Software Systems Engineering (Prof. Dr. Klaus Pohl) at the University of Duisburg-Essen. He worked in several research projects where he was able to expand his knowledge in the domain of Requirements Engineering for software-intensive Embedded Systems, as well as in those of model-based Context Analysis and context-based Quality Assurance.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Jan Christoph Wehrstedt works as a mathematician at the Technology Field Automation & Control at Siemens Corporate Technology. Currently he is Senior Key Expert for Efficient Simulation Driven System Development. He is the project manager of several business (Siemens internal) and public funded projects dealing with the integration of simulation and modeling approaches towards a simulation based engineering of technical systems and plants and it’s embedding into PLM lifecycle and tools.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Veronika Brandstetter is a mathematician in the Technology Field Automation & Control at Siemens Corporate Technology. She is developing methods for seamless engineering and improved operation of technical systems based on simulation. Recently, she focused on simulation based design for manufacturing technologies. She has been working in various Siemens internal research projects as well as in publicly funded projects also managing part of them in different groups within the Technology Field.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Martin Tate is an IT consultant who has now personally run or rescued 52 projects to select off-the-shelf solutions, interviewed over 725 people to capture the requirements for selections and appraised over 1,000 candidate solutions. A ‘poacher turned gamekeeper’, he formerly worked for an IT provider and was trained to sell software. BCS, The Chartered Institute for IT, made him a Chartered Fellow for eminence in evaluating software and recently published his book, a practitioner guide to procuring off-the-shelf IT.

• IT Requirements when Buying, not Making

Dr. Christof Ebert is managing director at Vector Consulting Services. He supports clients around the world to improve product strategy and product development and to manage organizational changes. A trusted advisor for companies around the world, member of industry boards, he lectures at the Universities of Stuttgart and at the Sorbonne in Paris. He authored several books including the popular “Systematic Requirements Engineering”. Contact him at christof.ebert@vector.com

• Cyber Security Requirements Engineering
• Product Management

Stefan Meier is passionate about exploring and experimenting with new Requirements Engineering practices and methodologies. He many years of practical experience as Project Manager, Requirements Engineer  and Agile Coach. He loves talking to different stakeholders and sharpening their ideas and visions to get a crisp and clear understanding of their needs and values. 
He works at SPF Consulting and currently helps customers switching their requirements frameworks from waterfall processes towards agile approaches like Scrum. Additionally he is an conversant trainer for IREB CPRE FL, Visual Facilitation and Agile Requirements.

• Applying IREB RE practices in an agile environment

Albert Tort is the Research&Innovation Solutions Lead in Sogeti Spain. During the last years, he has been working as Quality Assurance and Software Control & Testing specialist in several projects for customers in different sectors (banking, airlines, insurance, procurement, etc.). Furthermore, he has been the lead of research&innovation projects developed at Sogeti. He was the winner of the “Capgemini-Sogeti Testing Innovation Awards 2015” for the submission of the best individual entry "Recover: Reverse Modeling and Up-To-Date Evolution of Functional Requirements in Alignment with Tests. He is also a member of the SogetiLabs community.

Previously, he served as a professor and researcher at the Services and Information Systems Engineering Department of the Universitat Politècnica de Catalunya-Barcelona Tech. As a member of the Information Modeling and Processing (MPI) research group, he focused his research on conceptual modeling, software engineering methodologies, OMG standards, knowledge management, requirements engineering, service science, semantic web and software quality assurance. Currently, he is also the coordinator of the postgraduate degree in Software Quality Assurance of the School of Professional & Executive Development of the Technical University Of Catalunya (BarcelonaTech).

He obtained his Computer Science degree in 2008 and he received his M.Sc. in Computing in 2009. In 2012 he presented the PhD thesis “Testing and Test-Driven Development of Conceptual Schemas”. He is the author of several publications in software engineering journals and conferences.

• KCycle: Knowledge-Based & Agile Software Quality Assurance
• The Recover Approach

Frank Rabeler is a Business Analyst at T-Systems in Germany, where he specializes in requirements engineering for telecommunications software systems. Previously he worked as a database expert with focus on data modeling. How to design documents, data models etc. in the best readable way? Questions like these have been challenging him over the last 25 years as an IT professional. For 15 years now he has been using Information Mapping as part of his daily work and he appreciates this method as a success factor - especially in RE.

• Readable requirements

Johan Zandhuis is Product manager at SYSQA BV, an organisation specialised in quality assurance in IT. The themes ‘creating value with IT’ and ‘getting grip on IT’ play a constant role when he’s doing the job. “Why are we doing this” is a question he likes to ask. Besides other publications Johan is co-author of the Dutch book ‘Grip op requirements’ based on the IREB syllabus. Also he is one of the initiators for the Dutch translation of the IREB-dictionary and the IREB foundation syllabus. Contact: jzandhuis@sysqa.nl

• Poor requirements?

Brett Bicknell is an engineer at Critical Software Technologies and has played a key role in a number of formal methods initiatives, including the FP7 ADVANCE project. His software engineering experience encompasses varying levels of criticality and verification and validation activities. His previous work includes embedded systems, solutions for data acquisition and analysis, and a number of European-funded R&D ventures. He holds a BSc degree in Physics.

• Advance
• Rigorous Verification

Karim Kanso has worked within the field of formal methods and software engineering for many years, on various projects in the domains of transportation and aerospace. He has received a PhD in theoretical computer science, and is actively interested in the question of how requirement engineering can be applied to new disciplines, such as autonomous system engineering? He is currently working on the ADVANCE programme at Critical Software Technologies.

• Advance
• Rigorous Verification

Brett Bicknell is an engineer at Critical Software Technologies and has played a key role in a number of formal methods initiatives, including the FP7 ADVANCE project. His software engineering experience encompasses varying levels of criticality and verification and validation activities. His previous work includes embedded systems, solutions for data acquisition and analysis, and a number of European-funded R&D ventures. He holds a BSc degree in Physics.

• Rigorous Verification

Karim Kanso has worked within the field of formal methods and software engineering for many years, on various projects in the domains of transportation and aerospace. He has received a PhD in theoretical computer science, and is actively interested in the question of how requirement engineering can be applied to new disciplines, such as autonomous system engineering? He is currently working on the ADVANCE programme at Critical Software Technologies.

• Rigorous Verification

Daniel McLeod has worked on a variety of imaging sensor systems in the Airborne, Land and Naval domains. His previous work includes algorithm development, system design, requirements analysis and verification and project management. He is currently working within the smart energy domain on a Low Voltage monitoring system and a system for automated control of low voltage transformers in response to customer demand and distributed generation.

• Rigorous Verification

Jens Schirpenbach has been working as a consultant in the area of Product Lifecycle management for more than 12 years focusing on operations transformation in the area of Engineering and Services. He worked as a solution architect and project manager for diverse projects, essentially in the automotive, aerospace and manufacturing industry. He managed a team for PLM at a major European consultancy. After eleven years in consulting he founded P&PM Solutions & Consulting.
He has a joint master degree in mechanical Engineering and business administration of the University of Darmstadt, Germany.

• Opportunities & Approaches

Cristina Palomares is a PhD student in the Software Engineering for Information Systems Research Group (GESSI) at the Universitat Politècnica de Catalunya (UPC). Her PhD thesis deals about the construction, use and evolution of software requirement patterns for the reuse of requirements knoledge.

She has published several papers and presented posters and demos in requirements engineering conferences like in IEEE International Requirements Engineering Conference (RE) and the International Working Conference on Requirements Engineering: Foundation for Software Quality (REFSQ). She is the coordinator of developers of the PABRE System for supporting requirements reuse.

• What is the Relevance of Requirements Engineering Research to Practitioners?
• Requirements Reuse

Dr. Carme Quer is associate professor in the Service and Information System Engineering department (ESSI) at the Universitat Politècnica de Catalunya (UPC). She is member of the Software Engineering for Information Systems Research Group (GESSI) at the UPC. Her main research lines are requirements engineering and software quality.

She has published several papers in requirements engineering conferences like in the IEEE International Requirements Engineering Conference (RE) and the International Working Conference on Requirements Engineering: Foundation for Software Quality (REFSQ). She was General Chair of the Workshop on Requirements Engineering (WER) held in 2008.

• What is the Relevance of Requirements Engineering Research to Practitioners?
• Requirements Reuse

Xavier Franch is Professor at the Universitat Politècnica de Barcelona (UPC-BarcelonaTech), Spain. He is Council Member and Full Member of the IREB association. He has published over 200 peer-reviewed papers in conferences and journals, many of them related to requirements engineering. He was Program Co-Chair of the RE’16 and REFSQ’11 conferences, and he belongs to the Editorial Board of the Requirements Engineering Journal (Springer) and Information Software and Technology (IST) journals, among others. He is coordinator of the Q-Rapids project and participates in the OpenReq project, both in the H2020 programme. He organizes workshops concerning requirements engineering for NLP4RE, CrowdRE, JIT-RE and others.

• What is the Relevance of Requirements Engineering Research to Practitioners?
• Requirements Reuse

Erik van Veenendaal (www.erikvanveenendaal.nl) is a leading international consultant and trainer, and a widely recognized expert in the area of software testing and quality management.

He is the founder of Improve Quality Services BV (www.improveqs.nl). He holds the EuroSTAR record, winning the best tutorial award three times! In 2007 he received the European Testing Excellence Award for his contribution to the testing profession over the years. He has been working as a test manager and consultant in various domains for more than 20 years. He has written numerous papers and a number of books, including “Practical Risk-Based Testing: The PRISMA Approach” and “ISTQB Foundations of Software Testing”. He is one of the core developers of the TMap testing methodology and a participant in working parties of the International Requirements Engineering Board (IREB). Erik is also a former part-time senior lecturer at the Eindhoven University of Technology, vice-president of the International Software Testing Qualifications Board (2005–2009) and currently board member of the TMMi Foundation.

You can follow Erik on twitter via @ErikvVeenendaal.

• RE for Testers