The document discusses adopting code reviews in agile environments. Traditional code reviews are resource-intensive. An industrial case study found reviews were often skipped due to lack of time at the end of sprints. The paper proposes Continuous Changeset-Based Reviews (CCBR) as an alternative. CCBR makes reviews continuous, asynchronous tasks based on automated rules. It was implemented in a review tool integrated with Eclipse called ReviewClipse. An empirical evaluation is planned to compare CCBR to traditional reviews.

1. Mario Bernhart, Andreas Mauczka, Thomas Grechenig Research Group for Industrial Software (INSO) Vienna University of Technology, Austria www.inso.tuwien.ac.at

2. Introduction Code reviews have many benefits, most importantly to find bugs early [1, 2, 3] It is commonly accepted that code reviews are resource-intensive [4] Due to the lack of time and resources many (agile) software development teams do not perform traditional code reviews [5] Code reviews support knowledge sharing [18] and collective code ownership [22]

3. Code reviews in agile environm. Formal reviews such as the IEEE1028 [2] tend to be too heavyweight in agile contexts [4, 5] There is a growing interest in code reviews and review tools in the agile community [24] An empirical study [25] proposes a combination of pair programming and code reviews  Q: How to adopt traditional code reviews to support reviews in an agile environment?

4. Indust. case: context & problem EHR exchange service for hospitals Agile software development project, 24 months, Team of 7, sprint length 4 weeks Planned code reviews for 4 days at the end of each sprint : 1d inspection, 2d rework, 1d re-inspection  Reviews were mostly challenged or skipped due to time and resource lack especially at the end of the sprint

5. Adoption strategy Make the reviews a continuous task Make each review task smaller Create review tasks automatically based on individual team rules Make review asynchronous and support distributed reviewing Provide a first-class IDE integration for developers  Continuous Changeset-Based Review CCBR

6. CCBR description Setup = List of (author, reviewer, filter) E.g. (Peter, Mike, *) + (*, Chris, *test*.java) + … Continuous review workflow: The developer commits to the SCM If there is a matching rule: review task is auto-created The review is executed by using the compare-view to the previous version of the change-set The review result is consumed by the author A (negative) review result is followed up and may create a corrective task for the author

7. CCBR attributes Process Coherence Review is done shortly after the development Rework is done shortly after the original work  “ It's All about Feedback and Change” [23] Information Coherence Changes within one timeframe often correlate [15] Task size small, typically <200 LOC per review task

8. CCBR vs. traditional reviews (TR) Inspection Re-work Re-inspection t t Development effort Development effort Inspection, re-work and re-inspection effort TR CCBR

9. Limitations of CCBR TR sees the „whole“ whereas CCBR only refers to a „small piece“ Focus on a stable state (TR) vs. the creation process (CCBR) The sum of changed lines in TR < CCBR one line of code may be changed more than once Pre-commit reviews vs. Post-commit reviews

10. Review Tool for CCBR Eclipse integrated easy to use UI Review scope = one changeset in the SVN No additional server (XML/SVN based) Works offline Works with Subversive and Subclipse Flexible filtered review assignments Create Mylyn tasks out of (bad) reviews Freeware , 10.000+ downloads www.inso.tuwien.ac.at/projects/reviewclipse/

11. ReviewClipse Screenshot

12. ReviewClipse Screenshot

13. Planned Empirical Evaluation Research Questions Is CCBR equally effective as TR? Is CCBR equally efficient as TR? Is the rework effort of CCBR < TR? Plan Prestudy with 3/3 and 6 subjects of A and B A: In parallel study 30/30 (targets question 1 + 2) B: In serial study 60 (targets question 3)

14. Future Work – Mylyn Reviews Mylyn Reviews is a task-based code review plugin that integrates with Mylyn Main Features: Do code reviews based on Mylyn tasks Incorporate the review tasks in the Mylyn task list Provide inline-commenting for source code reviews Framework for other review tool integrations www.eclipse.org/reviews

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