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

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 1. Planning 2. Preparation 3. Meeting 4. Reporting results 5. Rework

7 1. Planning Schedule inspection meeting (time and place) [Moderator] Invite Reviewers [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

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

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

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?