# Durable Testing

> Software testing fundamentals for developers and AI agents. The 7 testing principles, the SDLC and STLC, and the test pyramid, with hand-drawn diagrams and rules agents can follow. Built by Durable Quality.

Every page is available as Markdown at the URLs below, or by requesting the page URL with `Accept: text/markdown`.

## Guide

- [The 7 testing principles](https://durableqa.xyz/durable-testing/testing-principles.md): The seven principles of software testing (ISTQB), explained with diagrams and turned into rules that developers and AI agents can follow: risk-based testing, early testing, defect clustering and more.
- [SDLC & STLC](https://durableqa.xyz/durable-testing/sdlc-stlc.md): The software development life cycle (SDLC) and software testing life cycle (STLC) phase by phase, with entry and exit criteria, deliverables and the V-model that links them.
- [The testing triangle](https://durableqa.xyz/durable-testing/test-pyramid.md): The test pyramid (testing triangle): how many unit, integration and end-to-end tests to write, why the shape works, anti-patterns like the ice-cream cone, and variants like the testing trophy.

## For agents

- [Rules for agents](https://durableqa.xyz/durable-testing/rules.md): all 19 rules in one block, for AGENTS.md or CLAUDE.md.
- [Claude skill](https://durableqa.xyz/durable-testing/skills/durable-testing/SKILL.md): install at ~/.claude/skills/durable-testing/SKILL.md.

## Optional

- [Full guide in one file](https://durableqa.xyz/durable-testing/llms-full.txt)