Create comprehensive test suite

[Xaxxoo]

Description

Build a robust testing infrastructure to ensure reliability and maintainability.

Tasks

• Set up Jest testing framework
• Create unit test framework for services
• Implement integration tests with test database
• Build e2e API tests
• Create test data factories
• Implement test coverage reporting
• Set up automated test runs for CI

Acceptance Criteria

• Unit tests cover core business logic
• Integration tests verify database interactions
• E2E tests cover API endpoints
• Test coverage meets defined thresholds
• Documentation for testing approach is included