Integration Testing Interview Questions

Integration testing: 1) Tests interactions between components/modules, 2) Verifies combined functionality, 3) Tests real dependencies (vs mocked in unit tests), 4) Focuses on component communication, 5) Tests larger parts of the application together. More comprehensive but slower than unit tests.

Setup includes: 1) Configuring test environment, 2) Setting up test databases/services, 3) Creating test fixtures, 4) Configuring global setup/teardown, 5) Setting appropriate timeouts. Example: setupFilesAfterEnv for global setup.

Common patterns: 1) Component interaction testing, 2) API integration testing, 3) Database integration testing, 4) Service integration testing, 5) End-to-end flows. Focus on testing interfaces between parts.

Test data handling: 1) Setup test databases, 2) Create seed data, 3) Manage test data isolation, 4) Clean up after tests, 5) Use realistic test data. Important for meaningful integration tests.

Mocking in integration tests: 1) Mock external services selectively, 2) Keep core integrations real, 3) Mock non-essential dependencies, 4) Use realistic mock data, 5) Balance between isolation and realism.

API integration testing: 1) Test real API endpoints, 2) Verify request/response handling, 3) Test error scenarios, 4) Check authentication/authorization, 5) Test API versioning. Use actual HTTP calls.

Database testing practices: 1) Use test database instance, 2) Reset database state between tests, 3) Test transactions and rollbacks, 4) Verify data integrity, 5) Test database migrations.

Test isolation involves: 1) Independent test databases, 2) Cleaning up test data, 3) Resetting state between tests, 4) Isolating external services, 5) Managing shared resources. Prevents test interference.

Service testing strategies: 1) Test service communication, 2) Verify service contracts, 3) Test service dependencies, 4) Check error handling, 5) Test service state management.

Async handling: 1) Use async/await syntax, 2) Set appropriate timeouts, 3) Handle promise chains, 4) Test concurrent operations, 5) Verify async state changes. Important for realistic testing.

Component communication testing: 1) Test props passing, 2) Verify event handling, 3) Test context updates, 4) Check state propagation, 5) Test component lifecycles. Focus on interaction points.

Microservice testing: 1) Test service discovery, 2) Verify service communication, 3) Test failure scenarios, 4) Check service dependencies, 5) Test service scaling. Consider distributed nature.

Data flow testing: 1) Verify data passing, 2) Test state updates, 3) Check data transformations, 4) Test data validation, 5) Verify data consistency. Focus on data integrity.

External service testing: 1) Test API contracts, 2) Handle authentication, 3) Test error scenarios, 4) Verify data formats, 5) Test service availability. Consider service stability.

Error handling testing: 1) Test error propagation, 2) Verify error recovery, 3) Test error boundaries, 4) Check error logging, 5) Test error state management. Important for reliability.

Authentication testing: 1) Test login flows, 2) Verify token handling, 3) Test permission checks, 4) Check session management, 5) Test authentication errors. Critical for security.

State management testing: 1) Test store interactions, 2) Verify state updates, 3) Test state synchronization, 4) Check state persistence, 5) Test state cleanup. Focus on data flow.

Cache testing: 1) Test cache operations, 2) Verify cache invalidation, 3) Test cache consistency, 4) Check cache performance, 5) Test cache failures. Important for performance.

Queue testing: 1) Test message publishing, 2) Verify message consumption, 3) Test queue operations, 4) Check message ordering, 5) Test queue errors. Focus on reliability.

File system testing: 1) Test file operations, 2) Verify file permissions, 3) Test file streams, 4) Check file cleanup, 5) Test file locks. Consider system interactions.

Complex integration: 1) Test multi-step flows, 2) Verify system interactions, 3) Test state transitions, 4) Check data consistency, 5) Test recovery scenarios. Focus on system behavior.

Distributed testing: 1) Test network partitions, 2) Verify consensus protocols, 3) Test leader election, 4) Check data replication, 5) Test system recovery. Consider CAP theorem.

Real-time testing: 1) Test WebSocket connections, 2) Verify event streaming, 3) Test pub/sub patterns, 4) Check message ordering, 5) Test connection recovery. Focus on timing.

Scalability testing: 1) Test load distribution, 2) Verify system capacity, 3) Test resource scaling, 4) Check performance degradation, 5) Test bottlenecks. Important for growth.

Consistency testing: 1) Test eventual consistency, 2) Verify data synchronization, 3) Test conflict resolution, 4) Check consistency models, 5) Test partition tolerance. Critical for reliability.

Resilience testing: 1) Test failure scenarios, 2) Verify system recovery, 3) Test circuit breakers, 4) Check fallback mechanisms, 5) Test degraded operations. Focus on reliability.

Monitoring testing: 1) Test metric collection, 2) Verify alerting systems, 3) Test logging integration, 4) Check monitoring accuracy, 5) Test monitoring scalability. Important for operations.

Security testing: 1) Test security protocols, 2) Verify access controls, 3) Test encryption, 4) Check security boundaries, 5) Test security monitoring. Critical for protection.

Compliance testing: 1) Test regulatory requirements, 2) Verify audit trails, 3) Test data protection, 4) Check policy enforcement, 5) Test compliance reporting. Important for regulations.