Software quality

In the context of software engineering, software quality refers to two related but distinct notions:

• Software’s functional quality reflects how well it complies with or conforms to a given design, based on functional requirements or specifications. That attribute can also be described as the fitness for purpose of a piece of software or how it compares to competitors in the marketplace as a worthwhile product. It is the degree to which the correct software was produced.
• Software structural quality refers to how it meets non-functional requirements that support the delivery of the functional requirements, such as robustness or maintainability. It has a lot more to do with the degree to which the software works as needed.

Many aspects of structural quality can be evaluated only statically through the analysis of the software inner structure, its source code (see Software metrics), at the unit level, and at the system level (sometimes referred to as end-to-end testing), which is in effect how its architecture adheres to sound principles of software architecture outlined in a paper on the topic by Object Management Group (OMG).
— Wikipedia

References

• Casey and Uncle Bob
• I don’t love the single responsibility principle
• Abstraction Bad? | Clean Code : Horrible Performance : (Clip) Interview - YouTube
• Response to a Reporter Regarding “Clean Code, Horrible Performance”