pact-testing-strategies

# PACT Testing Strategies

Testing guidance for the Test phase of PACT. This skill provides frameworks
for designing comprehensive test suites and links to detailed testing patterns.

## Test Pyramid

The test pyramid guides the distribution of test types for optimal coverage and speed.

```
                    /\
                   /  \      E2E Tests (Few)
                  /    \     - Critical user journeys
                 / E2E  \    - Slow, expensive
                /--------\
               /          \  Integration Tests (Some)
              /Integration \  - API contracts
             /--------------\  - Service interactions
            /                \
           /    Unit Tests    \ Unit Tests (Many)
          /                    \ - Fast, isolated
         /______________________\ - Business logic
```

### Coverage Targets

| Layer | Target | Focus | Speed |
|-------|--------|-------|-------|
| **Unit** | 80%+ line coverage | Business logic, edge cases | <1s per test |
| **Integration** | Key paths covered | API contracts, data flow | <10s per test |
| **E2E** | Critical flows only | User journeys, happy paths | <60s per test |

---

## Unit Testing Patterns

### Arrange-Act-Assert (AAA)

```javascript
describe('OrderService', () => {
  describe('calculateTotal', () => {
    it('should apply discount for orders over $100', () => {
      // Arrange
      const orderService = new OrderService();
      const items = [
        { price: 50, quantity: 2 },
        { price: 20, quantity: 1 }
      ];

      // Act
      const total = orderService.calculateTotal(items);

      // Assert
      expect(total).toBe(108); // $120 - 10% discount
    });
  });
});
```

### Test Behavior, Not Implementation

```javascript
// BAD: Testing implementation details
it('should call repository.save once', () => {
  await userService.createUser(userData);
  expect(userRepository.save).toHaveBeenCalledTimes(1);
});

// GOOD: Testing behavior
it('should create a user with has