Code Quality
Practices, tools, and metrics for maintaining readable, maintainable, testable, and defect-free code over time.
seed#code-quality#linting#testing#static-analysis#maintainability
What it is
Code quality is a set of attributes making code easy to understand, modify, and maintain. It's not just "it works" — it's "it works, it's readable, it's testable, and the next developer will understand it."
Dimensions
| Dimension | Key question | How to measure |
|---|---|---|
| Readability | Understandable without explanation? | Code review, cognitive complexity |
| Maintainability | Easy to modify? | Coupling, cohesion, module size |
| Testability | Can be tested in isolation? | Dependency injection, mocks needed |
| Consistency | Follows project conventions? | Linting, automatic formatting |
| Complexity | Simpler than necessary? | Cyclomatic complexity, lines per function |
Tools
| Category | Tools |
|---|---|
| Linting | ESLint, Biome, Ruff |
| Formatting | Prettier, Black |
| Type checking | TypeScript, mypy |
| Static analysis | SonarQube, CodeClimate |
| Testing | Jest, Vitest, pytest |
CI automation
- lint: eslint, prettier --check
- typecheck: tsc --noEmit
- test: vitest run
- coverage: vitest --coverageWhy it matters
Code quality is not a luxury — it is what determines long-term development velocity. Clean code is modified with confidence, messy code generates fear of change. Quality practices are an investment that pays off in every future iteration.
References
- Clean Code — Robert Martin.
- ESLint Getting Started — ESLint, 2024. Standard linting tool for JavaScript.