Testing Strategies for Microservices

A robust testing strategy is essential for confidence in microservices deployments.

The Testing Pyramid

• Unit Tests: Fast, isolated, mock dependencies
• Integration Tests: Test with real databases using Testcontainers
• Contract Tests: Ensure API compatibility between services
• E2E Tests: Verify complete user journeys

Using Testcontainers

@Testcontainers
@SpringBootTest
class OrderRepositoryTest {
    @Container
    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:15");
    
    @DynamicPropertySource
    static void configureProperties(DynamicPropertyRegistry registry) {
        registry.add("spring.datasource.url", postgres::getJdbcUrl);
    }
    
    @Test
    void shouldSaveOrder() {
        Order order = new Order("customer-1", BigDecimal.valueOf(100));
        Order saved = orderRepository.save(order);
        assertThat(saved.getId()).isNotNull();
    }
}

Contract Testing with Spring Cloud Contract

Contract.make {
    request {
        method GET()
        url "/api/products/123"
    }
    response {
        status OK()
        body(
            id: 123,
            name: "Product Name",
            price: 29.99
        )
    }
}

Invest in testing automation early—it pays dividends as your system grows.