feat(petition): add server-side validation and unit tests (#28)

[aaronaco]

Description

This PR adds comprehensive server-side validation for petition creation and updates, along with a complete unit test suite.

Closes #28

AI-Assisted Work Disclosure

This PR was developed with assistance from an AI tool for:

• Unit test structure and test cases: Guidance on organizing the test suite and identifying critical edge cases.
• Documentation updates: Help with formatting and clarifying project documentation for better readability.

Type of Change

• New feature
• Bug fix
• Tests
• Documentation

Changes

1. Server-Side Validation (Zod v4)

• Added validation schemas in functions/_shared/schemas.ts:

  • createPetitionSchema - Validates petition creation requests
  • updatePetitionSchema - Validates petition update requests
  • formatZodError - Formats Zod validation errors for API responses

• Implemented validation in API handlers:

  • POST /api/petitions - Validates creation requests with detailed error messages
  • PUT /api/petitions/[id] - Validates update requests with partial update support

• Validation Rules:

  • Title: 10-150 characters, required
  • Description: min 100 characters, required
  • Type: enum ("local" | "national"), required
  • Location: required for local petitions
  • Target count: 1 to 1,000,000, integer, defaults to 1000
  • Category IDs: array of numbers (optional)
  • Status: enum ("active" | "completed" | "closed") for updates

2. Unit Tests (Vitest)

• Created test suite with 42 tests total:

  • tests/unit/create-petition.test.ts (27 tests)
  • tests/unit/update-petition.test.ts (13 tests)
  • tests/unit/setup.test.ts (2 tests)

• Test Configuration:

  • Added vitest.config.ts:
  • Excluded e2e directory from Vitest (E2E tests use Playwright)
  • Ensured proper test isolation

3. Documentation

• Updated tests/README.md:
  • Added unit tests section
  • Documented test files and coverage
  • Added instructions for running tests

Testing

pnpm test:unit
# ✓ 42 tests passing

Test Coverage:

• Happy path scenarios (valid data)
• Sad path scenarios (invalid data with error messages)
• Edge cases (whitespace trimming, boundary conditions)
• Error message formatting validation

Checklist

• Follow existing naming conventions
• Code follows project style and linting rules
• Self-review completed
• Tests added or updated where appropriate
• Both success and error scenarios are covered by tests
• Tests can run independently and in isolation
• All tests pass locally
• Documentation updated where applicable
• No breaking changes to the public API

[aaronaco]

The CI lint check is failing due to pre-existing formatting issues in files unrelated to this PR. My changes are properly formatted. Should I fix these in this PR or should they be addressed separately?