Harness Checklist

Required and optional harnesses organized by pattern.

Required Harnesses by Pattern

Pattern	Required Harnesses	Optional Harnesses	Priority
L1: CRUD	- API contract verification - Basic unit tests - Integration tests	- Performance tests - Security scans	P0
L2: Sync MSA	- Service contract verification - Timeout/retry - Circuit breaker - Contract Testing	- Chaos engineering - Load tests	P1
L3: Async Events	- Event schema verification - Idempotency harness - Event ordering verification - Eventually Consistent tests	- Event replay - Dead Letter Queue	P1
L4: Saga	- Saga step verification - Compensating transaction verification - Failure scenario tests - Timeout harness	- Distributed tracing - Chaos engineering	P0
L5: Event Sourcing	- Event schema verification - Projection verification - Event replay - Event migration	- Snapshot strategy - Performance tests	P0

Harness Implementation Examples

Idempotency Harness (L3+)

# harness/idempotency_test.py
def test_duplicate_event_handling():
    """Verify identical results when receiving same event multiple times"""
    event = OrderCreatedEvent(orderId="123", ...)
    
    # First processing
    result1 = event_handler.handle(event)
    state1 = get_order_state("123")
    
    # Second processing (duplicate)
    result2 = event_handler.handle(event)
    state2 = get_order_state("123")
    
    # Results must be identical
    assert result1 == result2
    assert state1 == state2

Compensating Transaction Harness (L4+)

# harness/saga_compensation_test.py
def test_saga_compensation():
    """Verify that compensation logic works correctly on Saga failure"""
    saga = TravelBookingSaga()
    
    # 1. Flight reservation success
    saga.execute_step("ReserveFlight")
    assert flight_service.is_reserved("flight123")
    
    # 2. Hotel reservation success
    saga.execute_step("ReserveHotel")
    assert hotel_service.is_reserved("hotel456")
    
    # 3. Payment failure simulation
    with pytest.raises(PaymentFailedException):
        saga.execute_step("ChargePayment")
    
    # 4. Compensating transaction verification
    saga.compensate()
    assert not hotel_service.is_reserved("hotel456")  # cancelled
    assert not flight_service.is_reserved("flight123")  # cancelled

Projection Verification Harness (L5)

# harness/projection_test.py
def test_projection_consistency():
    """Verify event sourcing projection accuracy"""
    # 1. Create events
    events = [
        AccountOpenedEvent(accountId="A1", balance=1000),
        MoneyDepositedEvent(accountId="A1", amount=500),
        MoneyWithdrawnEvent(accountId="A1", amount=200),
    ]
    
    # 2. Store events
    for event in events:
        event_store.append(event)
    
    # 3. Update projection
    projection_service.rebuild("AccountBalanceView")
    
    # 4. Verify Read Model
    balance_view = read_db.get_account_balance("A1")
    assert balance_view.balance == 1300  # 1000 + 500 - 200
    assert balance_view.version == 3

Harness Priority Guide

P0 (Required)

Project failure results in data loss or serious business impact

• Example: Compensating transaction verification, event schema verification

P1 (Strongly Recommended)

Project failure results in service outage or user experience degradation

• Example: Timeout/retry, idempotency verification

P2 (Optional)

Quality improvement or operational convenience

• Example: Performance tests, chaos engineering

CI/CD Integration

Automation Pipeline

# .github/workflows/aidlc-validation.yml
name: AIDLC Validation

on: [push, pull_request]

jobs:
  validate-ontology:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Validate Ontology
        run: |
          aidlc-cli validate-ontology --path ontology/
  
  run-harness:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Run Harness Tests
        run: |
          aidlc-cli run-harness --suite saga
          aidlc-cli run-harness --suite idempotency
  
  quality-gate:
    runs-on: ubuntu-latest
    needs: [validate-ontology, run-harness]
    steps:
      - name: Check Quality Gate
        run: |
          aidlc-cli quality-gate --threshold 80

Next Steps

• Verification Methodology: Harness verification and quality assurance
• Ontology Guide: Ontology writing methods