API Testing Guide
Test types, tools, checklist, and best practices.
Test Types
Unit Tests
Individual endpoint tests
Tools: Jest, Mocha
Integration Tests
Multiple components together
Tools: Postman, Newman
Load Tests
Performance under stress
Tools: k6, Artillery
Security Tests
Vulnerability scanning
Tools: OWASP ZAP, Burp
Contract Tests
API agreement validation
Tools: Pact, Spring Cloud Contract
Smoke Tests
Basic functionality check
Tools: Custom scripts
Testing Checklist
✓ Test all endpoints
✓ Validate response schemas
✓ Check error handling
✓ Test authentication
✓ Verify authorization
✓ Test rate limiting
✓ Check pagination
✓ Test edge cases
Best Practices
Isolated test environment
Reset state between tests
Use realistic data
Automate test runs
Document test cases
Version test suites
Mock external services
Test both success and failure
Common Mistakes
✗ Testing in production
✗ Ignoring edge cases
✗ No authentication tests
✗ Missing error scenarios
✗ Tests depend on each other
✗ Hard-coded test data
✗ No cleanup after tests
✗ Skipping security tests
API Testing Workflow
1. Document API endpoints. 2. Create test environment. 3. Write unit tests per endpoint. 4. Test success responses. 5. Test error responses. 6. Validate schemas. 7. Test authentication flows. 8. Test authorization boundaries. 9. Run integration tests. 10. Perform load testing. 11. Security scan. 12. Automate in CI/CD. API testing = quality assurance. Untested API = unknown behavior. Test all paths, automate runs, monitor in production."