Software quality

Every day in our work we are faced with a rather abstract concept of “software quality,” and if you ask a question to a tester or a programmer - “what is quality?”, Then everyone will find their own interpretation. Consider the definition of "software quality" in the context of international standards:

[1061-1998 IEEE Standard for Software Quality Metrics Methodology]
Software quality is the degree to which software has the desired combination of properties.

[ISO 8402: 1994 Quality management and quality assurance]
Software quality is a combination of software characteristics related to its ability to meet stated and perceived needs.

Software quality characteristics

Functionality (Functionality) - is determined by the ability of the software to solve tasks that meet the fixed and perceived needs of the user, given the conditions of use of the software. Those. This characteristic is responsible for ensuring that the software works properly and accurately, interoperably, meets industry standards and is protected from unauthorized access.

Reliability - the ability of the software to perform the required tasks in the designated conditions for a given period of time or a specified number of operations. The attributes of this characteristic are the completeness and integrity of the entire system, the ability to recover independently and correctly after failures, and fault tolerance.

Usability is the ability to easily understand, learn, use and attractive software for the user.

Efficiency (Efficiency) - the ability of software to provide the required level of performance in accordance with the allocated resources, time and other designated conditions.

Maintainability is the ease with which software can be analyzed, tested, modified to correct defects, to implement new requirements, to facilitate further maintenance and to adapt to the named environment.

Portability (Portability) - describes the software in terms of ease of its transfer from one environment (software / hardware) to another.

Software quality model

Currently, the most common and used multi-level model of software quality is presented in the ISO 9126 standard set . At the top level, 6 main characteristics of software quality are identified, each of which is defined by a set of attributes that have corresponding metrics for further evaluation (see Figure 1) .

Figure 1 - Software Quality Model (ISO 9126-1)