Code Inspections

1. Code Inspections CSSE 376, Software Quality Assurance Rose-Hulman Institute of Technology March 22, 2007

2. Outline • Inspections in general • That is, for any type of artifact • Fagan's original work on code inspections • Benefits and Costs of Inspections

3. Inspections in General

4. Inspection Fundamentals • Preparation • Led by a moderator • Recorded results

5. Inspection Roles • Moderator • schedules the inspection meeting • leads the meeting • Recorder • records results • publishes results • Reviewer(s) • prepares for inspection meeting • participates during meeting • Producer • one of the authors; distributes artifact • attends inspection meeting, but does not talk (except to answer questions)

6. Inspection Process • Planning • Preparation • Meeting • Reporting results • Rework

7. 1. Planning • Schedule inspection meeting (time and place) [Moderator] • InviteReviewers [Producer] • Prepare materials [Producer] • Distribute materials to Reviewers [Producer]

8. 2. Preparation • Reviewers read artifact • Reviewers annotate listing with comments • Reviewers keep track of time spent in preparation

9. 3. Inspection Meeting • A square or octagonal table is recommended • Moderator runs the meeting • Recorder keeps minutes: • preparation time of Reviewers • comments and commenters • Reviewers contribute comments • Producer attends, but remains silent unless asked a question

10. Dilbert on Moderating

11. Moderating the Session • Don't go too fast -- may miss things • Don't go too slow • may not cover all of artifact • reviewers may lose concentration • Keep group on task • Record important events • Keep session to 1-2 hours in length

12. Wrapping Up • Ask for final comments • Review action items • Recorder: send minutes to Moderator • Reviewers: send annotated listings to authors • Recorder or Moderator: send reports to participants and to management

13. 4. Reporting Results • Summary data is sent to management • how many people participated • when the meeting took place, and for how long • how many issues were found (may be categorized) • Detailed results are sent to participants • all issues with annotations • action items

14. 5. Rework • Authors review comments • Artifact is modified by Producers • Reviewers are notified of changes • Another inspection may be needed, depending on the number and severity of the original comments

15. Fagan’s Work on Code Inspections

16. Overview of Fagan's Work • Proposed use of code inspections • Demonstrated evidence that inspections were cost effective • 23% improvement in coding efficiency • careful to avoid the "Hawthorne effect"

17. Code Inspection Checklist Examples • Mistakes • improper use of programming language • errors in algorithm or declarations • Poor style • violations of standard coding style • confusing or misleading expressions

18. Categorizing Defects • Some errors are more serious than others • Some errors are more common than others • Objective is not perfect classification, but separation of major types

19. Sample Categories • Major -- require investigation • Minor -- may not need immediate attention • Cosmetic -- optional improvements

21. How many LOC per inspection? • Remember, 1-2 hours is desired length of inspection meeting • Generally 100-200 lines of code per hour is the proper pace • Thus, many inspection meetings are likely needed for the entire source code

22. Benefits and Costs

23. Why Do Inspections Work? • Preparation • reviewers find things that authors miss • Peer pressure • forces developers to work harder • Formal process • forces developers and reviewers to do a thorough job

24. Costs of Inspection • Time spent in preparation • Time spent in meeting • Overhead of scheduling meeting

25. How Could We Improve Inspections? (Some Ideas) • Reduce number of reviewers • Reduce time spent in meeting • Hold meeting asynchronously • Hold meeting via the web • What are the pros and cons to each of these?