Static Testing Methods in Software Development: Fagan Inspection and Peer Ratings, Slides of Quality Management

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SOFTWARE QUALITY ENGINEERING

STATIC TESTING

Today’s Agenda

Introduction to static testing Objective of static testing Static Testing Methods Inspections Walkthroughs Desk Checking Peer Ratings

Objectives of Static Testing

Static testing is the least expensive form of testing and has the largest

potential for reducing defects in software under development.

The primary objective of static testing is defect reduction in the software by

reducing defects in the documentation from which the software is developed.

Static Testing Approach

5 Consider using a two-step approach to static testing. In the first step, clean up the cosmetic appearance of the document: Syntax Checking i.e. Spelling , Grammar , Sentence Structure i.e. Punctuations , and formatting etc. The benefit of doing the first step is that when the document is cosmetically clean, the readers can concentrate on the content. The liability of skipping the first step is that if the document is not cosmetically clean, the readers will surely stop reading the document for meaning and start proofreading the content. In the second step, use whatever techniques seem appropriate to focus expert review on document contents e.g. Walkthrough, Inspection etc.

Inspection

Fagan Inspection Gilb Inspection Two Person Inspection N-Fold Inspection Meetingless Inspection

Generic Inspection Process

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Generic process/steps:

1. Planning and preparation (individual)

2. Collection (group/meeting)

3. Repair (follow up)

Planning & Preparation Inspection / Collection Correction & Follow-up

Entry Exit

• What are the objectives/goals of the inspection?
• What are the software artifacts to be inspected or the objects of the inspection?
• Who are performing the inspection?
• Who else need to be involved, in what roles, and with what specific response?
• What are the overall process, techniques, and follow-up activities of the inspection?

Fagan Inspection

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The defects which are incorrect or even missing functionality or

specifications can be classified as major defects: the software will not function

correctly when these defects are not being solved.

In contrast to major defects, minor defects do not threaten the correct

functioning of the software, but are mostly small errors like spelling mistakes

in documents or optical issues like incorrect positioning of controls in a

program interface.

Fagan Inspection

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Typical Operations

A typical Fagan Inspection Process consist of the following operations:

Planning:

• Preparation of Materials
• Arrangement of Participants
• Arrangement of Meeting Place

Overview:

• Authors/Inspectors meeting
• Assignment of roles

Preparation/ Individual Inspection:

• Independent Analysis/ Examination
• Code + Other documentation inspection
• Individual Results:
  • Questions
  • Potential Defects

Fagan Inspection

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Follow-up

• In the follow-up phase of a Fagan Inspection, defects fixed in the rework phase should be verified.
• The moderator is usually responsible for verifying rework. Sometimes fixed work can be accepted without being verified, such as when the defect was trivial. In non-trivial cases, a full re-inspection Is performed by the inspection team (not only the moderator).
• If verification fails, go back to the rework process.

Gilb Inspection

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1. Planning (same to Fagan inspection)
2. Kickoff (Overview)
3. Individual Checking (Preparation)
4. Logging Meeting (Inspection)
5. a) Edit (Rework) b) Process brainstorming
6. Edit Audit (Follow-up) Process brainstorming is added right after the inspection meeting. The focus of this step is root cause analysis aimed at preventive actions and process improvement in the form of reduced defect injections for future development activities The team size is typically about four to six people Checklists are extensively used, particularly for step 3

Inspection Session

16 The ideal time for the inspection session appears to be from 90 to 120 minutes. Since the session is a mentally taxing experience, longer sessions tend to be less productive. Most inspections proceed at a rate of approximately 150 program statements per hour. For that reason, large programs should be examined in multiple inspections, each inspection dealing with one or several modules or subroutines. Note that for the inspection process to be effective, the appropriate attitude must be established. If the programmer views the inspection as an attack on his or her character and adopts a defensive posture, the process will be ineffective. Rather, the programmer must approach the process with an ego less attitude so the the session can be productive

Two Person Inspection

17 Some software artifacts are small enough to be inspected by one or two inspectors Similarly, such reduced size inspection teams can be used to inspect software artifacts of limited size, scope or complexity The so called Two Person Inspection was proposed to simplify the Fagan inspection, with an Author-Inspector pair

Meeting less Inspection

19 Experimental evidences indicates that most of the discovered defects are indeed discovered by individual inspectors during the preparation step of Formal Inspections like Fagan and Gilb The defect detection ratio in the meeting session lies in the range of 5% to 30% Therefore there is a possibility of eliminating inspection meetings entirely, thus significantly reducing the overall inspection cost This results in a so called meetingless inspection, where individual inspectors do not communicate with each other

Meeting less Inspection

20 One of the main drawback of this approach is the high False Alarm rate Another drawback of this approach is duplication of errors Various ways of communication can be used to pass the individual inspection results to the author, e.g through direct communication with the author, or through some defect repository