Software Testing - QTP, Manual Testing Automation Testing, Load Runner

The purpose of this article is to define the term software quality attributes and to place that term in the context of SQA and software process improvement, SPI.

ISO/IEC 9126 provides a framework for the evaluation of software quality.

It defines six software quality attributes, also called quality characteristics:

* Functionality: are the required functions available, including interoperabilithy and security
* Reliability: maturity, fault tolerance and recoverability
* Usability: how easy it is to understand, learn, operate the software system
* Efficiency: performance and resource behaviour
* Maintainability: how easy is it to modify the software
* Portability: can the software easily be transfered to another environment, including installability


McCall identified three main perspectives for characterizing the quality attributes of a software product.

These perspectives are:-

# Product revision (ability to change).
# Product transition (adaptability to new environments).
# Product operations (basic operational characteristics).

Product revision
The product revision perspective identifies quality factors that influence the ability to change the software product, these factors are:-
# Maintainability, the ability to find and fix a defect.
# Flexibility, the ability to make changes required as dictated by the business.
# Testability, the ability to Validate the software requirements.

Product transition
The product transition perspective identifies quality factors that influence the ability to adapt the software to new environments:-
# Portability, the ability to transfer the software from one environment to another.
# Reusability, the ease of using existing software components in a different context.
# Interoperability, the extent, or ease, to which software components work together.

Product operations
The product operations perspective identifies quality factors that influence the extent to which the software fulfils its specification:-
# Correctness, the functionality matches the specification.
# Reliability, the extent to which the system fails.
# Efficiency, system resource (including cpu, disk, memory, network) usage.
# Integrity, protection from unauthorized access.
# Usability, ease of use.

In total McCall identified the 11 quality factors broken down by the 3 perspectives, as listed above.
For each quality factor McCall defined one or more quality criteria (a way of measurement), in this way an overall quality assessment could be made of a given software product by evaluating the criteria for each factor.
For example the Maintainability quality factor would have criteria of simplicity, conciseness and modularity.

# Boehm identified seven quality factors, namely:-

# Portability, the extent to which the software will work under different computer configurations (i.e. operating systems, databases etc.).
# Reliability, the extent to which the software performs as required, i.e. the absence of defects.
# Efficiency, optimum use of system resources during correct execution.
# Usability, ease of use.
# Testability, ease of validation, that the software meets the requirements.
# Understandability, the extent to which the software is easily comprehended with regard to purpose and structure.
# Flexibility, the ease of changing the software to meet revised requirements.

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