Code Quality
Measure, enforce, and improve code quality across languages.
Linting
JavaScript/TypeScript
bash
# ESLint — find issues
npx eslint src/ --format json | jq '[.[] | select(.errorCount > 0 or .warningCount > 0) | {file: .filePath, errors: .errorCount, warnings: .warningCount}]'
# Auto-fix
npx eslint src/ --fix
# Specific rules only
npx eslint src/ --rule '{"no-unused-vars": "error"}'
Python
bash
# Ruff — fast linter + formatter ruff check src/ ruff check src/ --fix # Type checking mypy src/ --ignore-missing-imports # Both together ruff check src/ && mypy src/
Go
bash
# golangci-lint — meta linter
golangci-lint run ./...
# With specific linters
golangci-lint run --enable gosec,govet,errcheck,staticcheck ./...
# JSON output
golangci-lint run --out-format json ./... | jq '.Issues[] | {file: .Pos.Filename, line: .Pos.Line, linter: .FromLinter, text: .Text}'
Rust
bash
# Clippy — Rust linter cargo clippy -- -W clippy::all # Treat warnings as errors cargo clippy -- -D warnings # With suggestions cargo clippy --fix
Formatting
bash
# Prettier (JS/TS/CSS/JSON/MD)
npx prettier --check "src/**/*.{ts,tsx,js,jsx}"
npx prettier --write "src/**/*.{ts,tsx,js,jsx}"
# Ruff format (Python)
ruff format src/
ruff format --check src/
# gofmt (Go)
gofmt -l .
gofmt -w .
# rustfmt (Rust)
cargo fmt --check
cargo fmt
Code Coverage
bash
# Jest (JS/TS)
npx jest --coverage --json | jq '{lines: .coverageMap | to_entries | map(.value.s | to_entries | map(.value) | {total: length, covered: map(select(. > 0)) | length}) | {total: map(.total) | add, covered: map(.covered) | add} | {pct: (100 * .covered / .total | floor)}}'
# Simpler: just run and read summary
npx jest --coverage 2>&1 | tail -10
# pytest (Python)
pytest --cov=src --cov-report=term-missing
# Go
go test -coverprofile=coverage.out ./...
go tool cover -func=coverage.out | tail -1
# Rust
cargo tarpaulin --out stdout
Complexity Metrics
bash
# Python — cyclomatic complexity
radon cc src/ -a -s -nb
# Python — maintainability index
radon mi src/ -s -nb
# JavaScript/TypeScript — complexity via ESLint
npx eslint src/ --rule '{"complexity": ["warn", 10]}' --format json | jq '[.[] | .messages[] | select(.ruleId == "complexity") | {file: input.filePath, line: .line, message: .message}]'
Tech Debt Indicators
Look for these patterns:
bash
# TODO/FIXME/HACK comments grep -rn "TODO\|FIXME\|HACK\|XXX\|TEMP" src/ --include="*.ts" --include="*.py" --include="*.go" | wc -l # List them grep -rn "TODO\|FIXME\|HACK" src/ --include="*.ts" --include="*.py" # Long files (>300 lines) find src/ -name "*.ts" -o -name "*.py" | xargs wc -l | sort -rn | head -20 # Duplicate code detection (Python) # Install: pip install pylint pylint --disable=all --enable=duplicate-code src/
Notes
- •Run linting on changed files only in CI for speed:
eslint $(git diff --name-only --diff-filter=ACMR HEAD~1 | grep -E '\.(ts|tsx|js)$'). - •Coverage percentage alone is misleading — 80% with no edge case tests is worse than 60% with thorough tests.
- •Fix linting errors incrementally. Don't dump 500 fixes into one commit.
- •Complexity > 10 is a code smell. > 20 needs refactoring.