TypeScript Project Validation

Full validation workflow for TypeScript projects.

Quick Validation

# Full validation (typecheck + lint + format + test)
npx tsc --noEmit && npx eslint src/ && npx prettier --check src/ && npx vitest run

# With Biome (alternative)
npx tsc --noEmit && npx biome check src/ && npx vitest run

Validation Steps

1. Type Check

npx tsc --noEmit

2. Lint Check (ESLint)

npx eslint src/

Fix issues:

npx eslint --fix src/

3. Format Check (Prettier)

npx prettier --check src/

Fix issues:

npx prettier --write src/

4. Run Tests

# Full test suite
npx vitest run

# With coverage
npx vitest run --coverage

# Watch mode
npx vitest

Biome Alternative

All-in-one lint + format:

# Check all
npx biome check src/

# Fix all
npx biome check --apply src/

package.json Scripts

{
  "scripts": {
    "build": "tsc",
    "typecheck": "tsc --noEmit",
    "lint": "eslint src/",
    "lint:fix": "eslint --fix src/",
    "format": "prettier --write src/",
    "format:check": "prettier --check src/",
    "test": "vitest run",
    "test:watch": "vitest",
    "test:coverage": "vitest run --coverage",
    "validate": "npm run typecheck && npm run lint && npm run format:check && npm run test",
    "fix": "npm run lint:fix && npm run format"
  }
}

CI Configuration

# .github/workflows/ci.yml
name: CI

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'

      - run: npm ci

      - name: Type check
        run: npx tsc --noEmit

      - name: Lint
        run: npx eslint src/

      - name: Format check
        run: npx prettier --check src/

      - name: Test
        run: npx vitest run --coverage

      - uses: codecov/codecov-action@v4

Pre-commit Hooks

npm install -D husky lint-staged
npx husky init

// package.json
{
  "lint-staged": {
    "*.ts": ["eslint --fix", "prettier --write"],
    "*.{json,md}": "prettier --write"
  }
}

Validation Checklist

Check	Command	Fix
Types	tsc --noEmit	Fix type errors
Lint	eslint src/	eslint --fix src/
Format	prettier --check src/	prettier --write src/
Tests	vitest run	Fix failing tests
Coverage	vitest run --coverage	Add tests

Common Issues

Type errors

# Verbose output
npx tsc --noEmit --pretty

# Check specific file
npx tsc --noEmit src/problematic.ts

ESLint violations

# See all issues
npx eslint src/

# Fix automatically
npx eslint --fix src/

# Disable for line
// eslint-disable-next-line @typescript-eslint/no-explicit-any

Prettier issues

# Check what would change
npx prettier --check --write src/

# Fix all
npx prettier --write src/

Test failures

# Run specific test file
npx vitest run src/foo.test.ts

# Run with verbose output
npx vitest run --reporter=verbose

# Update snapshots
npx vitest run -u

bun Workflow

If using bun:

# Install
bun install

# Run commands
bun run typecheck
bun run lint
bun test

pnpm Workflow

If using pnpm:

# Install
pnpm install

# Run commands
pnpm run typecheck
pnpm run lint
pnpm test