Towards optimal quality requirement documentation in agile software development: a multiple case study

Context: Agile software development (ASD) promotes minimal documentation and often prioritizes functional requirements over quality requirements (QRs). The minimal documentation emphasis may be beneficial in reducing time-to-market for software. However, it can also be a concern, especially with QRs, since they are challenging to specify and document and are crucial for software success. Therefore, understanding how practitioners perceive the importance of QR documentation is valuable because it can provide insight into how they approach this task. It also helps in developing models and guidelines that support the documentation of QRs in ASD, which is a research gap. Objective: We aim to understand practitioners’ perceptions of QR documentation and factors influencing this task to derive a model that supports optimal QR documentation in ASD. Method: We conducted a multiple case study involving 12 participants from three cases that apply ASD. Results: Practitioners identify QR documentation as important and perceive it as contributing to ensuring quality, clarifying QRs, and facilitating decision-making. Time constraints, QR awareness, and communication gaps affect QR documentation. Missing and outdated QR documentation may lead to technical debt and a lack of common understanding regarding QRs. We introduce a model to support optimal QR documentation in ASD by focusing on the factors: time constraints, QR awareness, and communication gaps. The model provides a representation and explanation of the factors affecting QR documentation in ASD and identifies mitigation strategies to overcome issues that may occur due to these factors. Conclusion: The study reveals the importance of documenting QRs in ASD. It introduces a model that is based on empirical knowledge of QR documentation practices in ASD. Both practitioners and researchers can potentially benefit from the model. For instance, practitioners can analyze how time constraints or QR awareness affect documentation, see potential issues that may arise from them, and utilize strategies suggested by the model to address these issues. Researchers can learn about QR documentation in ASD and utilize the model to understand the topic. They can also use the study as a baseline to investigate the topic with other cases. Keywords-agile software development; documentation; quality requirements; non-functional requirements