vamseeachanta Testing Tdd London
Quick Start
// 1. Start with acceptance test (outside)
describe('User Registration', () => {
it('should register new user successfully', async () => {
const mockRepository = { save: jest.fn().mockResolvedValue({ id: '123' }) };
const mockNotifier = { sendWelcome: jest.fn() };
const service = new UserService(mockRepository, mockNotifier);
await service.register({ email: 'test@example.com' });
// 2. Verify behavior (interactions)
expect(mockRepository.save).toHaveBeenCalledWith(
expect.objectContaining({ email: 'test@example.com' })
);
expect(mockNotifier.sendWelcome).toHaveBeenCalledWith('123');
});
});
When to Use
- Testing object collaborations and message passing
- Contract-driven development with clear interfaces
- Outside-in development starting from user behavior
- When isolation of units is critical
- Service orchestration testing
- Testing HOW objects work together (not WHAT they contain)
Prerequisites
- Understanding of mock objects vs stubs
- Jest, Vitest, or similar testing framework with mocking support
- Clear separation of concerns in architecture
- Dependency injection pattern in codebase
References
Version History
- 1.0.0 (2026-01-02): Initial release - converted from tdd-london-swarm agent
Sub-Skills
- Configuration
- Example 1: Service Orchestration Test (+2)
- Mock Management (+2)
Sub-Skills
- Execution Checklist
- Error Handling
Sub-Skills
- London vs Chicago School (+2)
- 1. Outside-In Development (+2)
- Metrics & Success Criteria
- MCP Tools (+2)