Software Inspections and Walkthroughs Author: A. Frank Ackerman

Software Inspections and Walkthroughs Author: A. Frank Ackerman Presented by Cynthia Johnson EEL6883 1

Software Inspections “Software Inspections are a disciplined engineering practice for detecting and correcting defects in software artifacts, and preventing their leakage into field operations.” Don O'Neill, Don O' Neill Consulting for SEI 2

Software Walkthroughs a form of software peer review "in which a designer or programmer leads members of the development team and other interested parties through a software product, and the participants ask questions and make comments about possible errors, violation of development standards, and other problems" ( IEEE Std. 1028-1997, IEEE Standard for Software Reviews, clause 38. 3

What’s the difference? An inspection is a more formal process than a walkthrough used to collect metrics or statistics about the software process Walkthrough is a more informal version of an inspection 4

Why inspect software? Routine production of reliable software within budget and on schedule continues to elude most development organizations. While efforts are ongoing to make development an industrial process, much of the work is still done by “intellectual artisans” Artisan’s work is inherently difficult to bond and can not be specified precisely. Inspections are a method to reduce variability and tighten process control. 5

History of Inspections M.E. Fagan of IBM first defined inspections in 1976. E. Yourdon was among the first to publish a book on inspections in 1978. IEEE standard covering inspections first appeared in 1988. 6

What do inspections cover? Inspections and walkthroughs are primarily intended to discover defects in software artifacts. This is a static analysis technique of software testing. In addition, inspections address three major tasks of process management: planning, measurement, control. 7

Inspection metrics Inspections are used to collect quantitative quality data at defined points in the development process. This can be used to give feedback to the developers, feed-forward to future development, and feed-into future steps of process. Can also provide data on effectiveness of inspection techniques. 8

What can be inspected? Inspections can be held a various points in development process. Fagan recommended inspections on: Detailed design Cleanly compiled code Completion of unit test 9

Who is involved? At a minimum a formal inspection includes: Designated moderator Author of the work At least one peer inspector Walkthroughs generally do not include designated moderator and are often led by the author of the software. 10

Steps of inspection Planning Overview Preparation Meeting Rework Follow-up 11

Planning Planning begins when entry criteria for inspection type is met. Moderator is selected – usually a peer or technical leader Selection may be made by developer, but this is generally not an ideal situation Management is encouraged not to look at individual inspection results Moderator verifies that product meets entry criteria and schedules future steps. 12

Overview Presentation to inspectors with any background information needed to properly review software product. Purpose is educational only Data collected is author preparation time and time spent on presentation. 13

Preparation Individual activity Author collects all material required for inspection Inspectors study the material and complete inspection log. Defects are noted at this step, but not collected 14

Meeting Meeting is conducted by moderator Agenda includes: Introduction Establishing readiness Examining material and recording defects Review defects Determine disposition Debrief Defect data is collected this time 15

Common meeting problems Interpersonal tensions are most likely to arise at this point Experienced moderators can detect and defuse this tension The more inspections that occur, the less likely interpersonal tensions are to interfere Effort should be made by all participants to keep emphasis on producing quality product, not making fault finding personal 16

Rework Performed by the author in response to defect disposition determined at meeting 17

Follow-up Moderator verifies that corrections are made Moderator completes inspection management report and defect summary report 18

Inspection Roles Author – developer of work product Moderator – an inspector responsible for organizing and reporting on inspection Reader – an inspector who guies the examination of the product Recorder – an inspector who enters all the defects found on the defect list Inspector – Member of inspection team. Often chosen to represent specific role- designer, tester, technical writer, SQA, etc 19

Inspection as Process Control When employed at various points through out the process, the completion of an inspection can trigger entry into a new development phase. Generally, Software Development Plan spells out entry and exit criteria and required participants in each type of inspection. 20

Aspects of inspections Initial introduction of inspection into an organization can cause anxiety and tension among developers When it becomes clear that management supports inspection as a quality improvement technique and not a witch hunt, the effectiveness of the inspection increases. 21

Inspection Data The collection and analysis of data is what sets inspections apart from other peer review techniques such as walkthroughs. This data can be used in a variety of ways by a variety of personnel. 22

Data customers First-line managers – amount of rework generates schedule information Next phase developers or verifiers get “intelligence” report on status of software Quality assurance personnel use data on amount of material inspected, amount of inspection material, speed of examination to examine inspection effectiveness 23

More data usage Quality assurance is responsible for recommending inspection and preparation rates – actual review data makes these more realistic Defect rates and types discovered at different points can point to most effective place to review. For example, design inspections may prove more cost effective than code. 24

Alternatives There is a “cost of quality” associated with walkthroughs and inspections. In software, person-hours are the highest measurable expense Many organizations find that the cost of inspection does not generate a return on investment Some inspect a percentage of code Others inspect only critical portions 25

Conclusions Inspections have been proven an efficient and effective method for improving software quality In conjunction with testing, audits and formal verification a successful, quality product can be produced 26

My opinion When done correctly, walkthroughs and inspections are valuable defect finding tools. When not supported by management or bought into by development personnel, they become “busy work” for developers. It is important for developers to not take criticism personally. It is equally important for inspectors to look for defects and not criticize because developer didn’t code exactly the way they would 27

References http://www.sei.cmu.edu/str/descriptions/in spections body.html IEEE Std. 1028-1997, IEEE Standard for Software Reviews 28