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intermediate Phase · Testing

API Testing

Test REST API endpoints for correctness and edge cases.

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API Testing

API Test Example

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureMockMvc
class ProductApiTest {

    @Test
    void shouldGetProductById() throws Exception {
        mockMvc.perform(get("/api/products/1"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.name").value("Laptop"))
            .andExpect(jsonPath("$.price").value(999.99));
    }

    @Test
    void shouldReturn404WhenProductNotFound() throws Exception {
        mockMvc.perform(get("/api/products/999"))
            .andExpect(status().isNotFound());
    }
}

API Best Practices

Design Principles

  • Use nouns, not verbs
  • Plural resource names
  • Consistent naming conventions
  • Proper HTTP status codes

Versioning

  • URI versioning (/v1/resource)
  • Header versioning
  • Deprecation policy

Documentation

  • OpenAPI/Swagger specs
  • Request/Response examples
  • Error code documentation
  • Rate limit documentation

Key Points

  • Understanding API Testing is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0 / 2 solved
API Testing Edge Cases

Identify and handle edge cases for API Testing. What happens under high load, with invalid input, or during failures?

Solution
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
API Testing Testing Strategy

Write a testing strategy for API Testing. Include unit tests, integration tests, and performance tests.

Solution
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. API testing validates?

Question 1 options

2. RANDOM_PORT in tests?

Question 2 options

3. What is a common mistake when implementing API Testing?

Question 3 options

Flashcards

Question

API testing validates?

Answer

Status, body, headers

Question

RANDOM_PORT purpose?

Answer

Avoid port conflicts

Question

API Testing best practices

Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1. Test status codes, response bodies, headers
  • 2. Test happy path and error cases
  • 3. Use @SpringBootTest(webEnvironment = RANDOM_PORT)
  • 4. Validate JSON with jsonPath

Interview Tips

  • Write API tests
  • Test error cases

Cheat Sheet

API Testing

  • Validate: status, body, headers
  • Test: happy path + error cases
  • RANDOM_PORT: avoid conflicts
  • jsonPath: validate JSON fields