CS608 Handouts

Week-01: Introduction to Software Quality Assurance

Quality popular view:

• Something “good” but not quantifiable
• Something luxury and classy

Quality professional view:

• Conformance to requirement  The requirements are clearly stated, and the product must conform to it  Any deviation from the requirements is regarded as a defect  A good quality product contains fewer defects
• Fitness for use:  Fit to user expectations: meet user’s needs  A good quality product provides better user satisfaction

What is quality?

What you see of high quality others do not see it like that. I depend on your requirements. For example, a university perfect registration system is not necessarily suitable to a school.

ISO Definition of Quality

ISO 8402 definition of QUALITY:

The totality of features and characteristics of a product or a service that bear on its ability satisfy stated or implied needs

ISO 9216 Model:

Quality characteristics

1. Functionality
2. Reliability
3. Usability
4. Efficiency
5. Maintainability
6. Portability

Other definition and concept

• Four Absolutes:

• Quality Means Conformance to Requirements. Both functional and non-functional
• Quality Comes from Prevention
• Quality is never ending improvement
• Quality is Zero Defects

Benefits of software quality

Decreased number of defects and errors in software Less rework as a result of less software defects Reduced development and maintenance cost Increased software reliability Increased customer satisfaction Happier software practitioners

Software Engineers and quality

Software engineers strive to control the

• Process applied: What is the best process (i.e SDLC) to be used for the development of software
• Resources expended: Make sure software development is finished in expected time and also using the estimated budget
• End product quality attributes: Make sure that the software it self is of a high quality and contains all features and requirements (functional and non functional)

Reasons for poor quality

1. Faulty requirements definition
2. Client-developer communication failures
3. Deliberate deviations from software requirements
4. Logical design errors
5. Coding errors
6. Non-compliance with documentation and coding instructions
7. Shortcomings of the testing process
8. User interface and procedure errors
9. Documentation errors

Software Quality: IEEE Definition

Software quality is:

(1) The degree to which a system, component, or process meets specified requirements. (2) The degree to which a system, component, or process meets customer or user needs or expectations.