Lecture # 23 Validating Requirements

Lecture # 23 Validating Requirements
It takes 30 minutes to correct a requirement defect in requirement phase
However it may take hours or may be days to correct a defect identified during system testing

A very good practice is to do test planning and create test cases. This reveals defects in requirements early in life cycle.

Validation Attempts to Ensure:
• SRS correctly describes system capabilities
• Requirement are complete and of high quality
• Consistent with each other
• Adequate basis for design and construction

Validation can be done using informal or formal approaches.

Informal approach includes
• Peer Desk check: Ask one colleague to look over your work product
• A passaround: in which you invite several colleagues to examine a deliverable
• A walkthrough: Author describes a deliverable and solicit comments on it

Among Formal Approaches we are going to discuss
• Inspection

Inspection:
• It was first defined by IBM
• Involves small teams of trained participants
• Not specific to requirements but can be used for any software workproduct
• Involves careful examination of work products to discover defects
• A high leverage SQA technique
• It is said that one hour spent in inspection avoids at least 10 hours of labour
• Therefore even being a lengthy task, it should not be avoided
• If there is not enough time, then risk analysis should be done to identify critical requirements and then inspection of those should be performed
• Inspection should not wait for the entire SRS to complete but it should be started as soon as 10% of SRS gets completed.

Participants of Inspection:
Should involve people having different perspectives
Normally four people are involved however the total number of people involved should not exceed 6

People involved can be
• Author or peer of author
• Author of any predecessor work product, e.g. person who document high level requirements
• People who will do work based upon item being inspected
• People who are responsible for work products that interface with items being inspected

Roles involved
Some tasks are delegated to people with in the inspection team
1- Moderator (Inspection leader)
a. Plans inspection with author
b. Coordinates and facilitates activities
c. Distributes the material, days before the meeting
d. Responsible for right focus of meeting
e. Reporting results
f. Follows up with author so that defects and issues raised are addressed
2- Author
a. Much passive role
b. Listens and responds to questions
c. Spotting errors that others don’t see
d. Incorporating the recommendations
3- Reader
a. Reads a requirement at a time
b. Paraphrases, that is explains in his own words
c. Other participants point out defects and issues
4- Recorder (Scribe)
a. Documents issues raised
b. Reads aloud what he has wrote to confirm accuracy

Pre-requisites of Inspection:
Avoids spending time on issues that can be solved before
Moderator should the following before proceeding
1- Document confirms to standard template (If any)
2- Spell checked
3- Layout errors resolved
4- Reference documents required by inspectors are available
5- Line numbers printed
6- Open issues are marked as TBD (To be determined)
7- Moderator did not find 3 major defects in 10 min of time

Inspection Stages
1- Planning
2- Overview Meeting
3- Preparation
4- Inspection Meeting
5- Rework
6- Followup