# Software Quality

**The cost shift**

AI cuts the cost of producing code, and expectations about delivery speed
rise with it — but a change still has to be read, tested, and trusted, and
that costs about what it always did. The bottleneck has moved to
verification.

This project reviews the ways of finding out whether software works, drawing
on the literature and on industry practice.

## What this project does

- **Surveys the methods in use.** Types, static analysis, tests, runtime
  checks, formal methods, monitoring: one page per method, each stating
  what uncertainty it reduces, the tools that implement it, and the
  evidence behind it. See [Methods](https://quality.stereobooster.com/methods.md).
- **Organizes them with a few classifications.** These are not new
  methods, and mostly not new vocabulary; where the field already has a
  standard taxonomy, the classifications reuse it and assemble the pieces
  into one cross-method frame. The payoff is that relationships become
  visible: differential, metamorphic, and property-based testing differ
  mainly in their *oracle*, not their inputs; coverage and exhaustiveness
  are points on the *guarantee* scale, signals of reach rather than
  methods in their own right. See [the axes](https://quality.stereobooster.com/axes.md).
- **Examines how AI shifts these practices.** Organized by AI's
  relationship to the oracle — where AI *is* the oracle, *consumes* one,
  or *writes* one. See [How AI fits into software quality](https://quality.stereobooster.com/ai.md).

Recommendations carry their evidence, or a plain note where it's thin;
practices that rest on repetition rather than data are named as folklore.

## The dimensions of quality

Quality is several distinct things, not a single scale (Garvin 1987)[^garvin1987] — and
each needs its own verification. Five dimensions are developed here:
**Functionality**, **Security**, **Reliability**, **Performance**,
**Maintainability**. Each aligns with an ISO/IEC 25010 product-quality
characteristic (ISO/IEC 2011)[^isoiec25010_2011] that carries a distinct verification
method. Each has its own failure modes, erosion signals, and methods in order
of adoption: see **[Quality dimensions](https://quality.stereobooster.com/quality-dimensions.md)** for the
per-dimension breakdown. **Usability** (likewise a 25010 characteristic) and
**Aesthetics** are named but left to their own mature fields.

## How to read this

The content answers two questions — *what verification methods
exist?* and *which should I reach for, given the quality dimensions
I care about?* — across these sections:

- **[Methods](https://quality.stereobooster.com/methods.md)** — the verification
  methods catalog: one page per method, listed
  the same way throughout. The [master table](https://quality.stereobooster.com/methods.md)
  lists every method on a row, and [the axes](https://quality.stereobooster.com/axes.md)
  defines the classification methodology.
- **[Quality dimensions](https://quality.stereobooster.com/quality-dimensions.md)** — which
  methods apply to a given quality dimension, and in what order.
- **[Choosing methods](https://quality.stereobooster.com/choosing.md)** — a heuristic for tying
  dimensions, axes, and methods together: given a part's stakes and the
  oracles, guarantee, and tooling on hand, which methods to reach for, in what
  order, and which to stage for later.
- **[AI](https://quality.stereobooster.com/ai.md)** — AI's effect on each method, with the
  open-source tools and studies that back each cell.
- **[Conventional](https://quality.stereobooster.com/conventional.md)** — the testing vocabulary
  most developers already use, reconciled with the rest: unit /
  integration / e2e mapped onto the axes, the pyramid critique, and the
  two category errors (*tests are not all verification*; *hygiene is not
  verification*).
- **[Recipes](https://quality.stereobooster.com/recipes.md)** — a small, opinionated
  appendix of practical configurations and snippets.
- **[Glossary](https://quality.stereobooster.com/glossary.md)** — project-wide vocabulary (*oracle*,
  *regression ceiling*, *by construction*, *folklore* as an
  evidence tier).
- **[About](https://quality.stereobooster.com/about.md)** — how the content is checked, what that does not
  guarantee, and who writes it.

## References

[^garvin1987]: Garvin, David A. 1987. "[Competing on the Eight Dimensions of Quality](https://hbr.org/1987/11/competing-on-the-eight-dimensions-of-quality)." *Harvard Business Review* 65 (6): 101–9. <https://hbr.org/1987/11/competing-on-the-eight-dimensions-of-quality>.
[^isoiec25010_2011]: ISO/IEC. 2011. *[ISO/IEC 25010:2011: Systems and software engineering — SQuaRE — System and software quality models](https://www.iso.org/standard/35733.html)*. International Organization for Standardization. <https://www.iso.org/standard/35733.html>.