Integration Testing Interview Questions

Integration testing involves: 1) Testing multiple components together, 2) Verifying component interactions, 3) Testing external dependencies, 4) End-to-end functionality verification, 5) Testing real subsystems. Unlike unit tests, integration tests focus on component interactions rather than isolated functionality.

Setup involves: 1) Configuring test environment, 2) Setting up test databases, 3) Managing external services, 4) Handling test data, 5) Configuring proper timeouts. Example: separate test configuration for integration tests.

Common patterns include: 1) Database integration testing, 2) API endpoint testing, 3) Service integration testing, 4) External service testing, 5) Component interaction testing. Focus on testing integrated functionality.

Test data handling: 1) Use test databases, 2) Implement data seeding, 3) Clean up test data, 4) Manage test state, 5) Handle data dependencies. Ensures reliable test execution.

Database testing practices: 1) Use separate test database, 2) Implement transactions, 3) Clean up after tests, 4) Handle migrations, 5) Manage connections efficiently. Ensures data integrity.

API testing involves: 1) Making HTTP requests, 2) Verifying responses, 3) Testing error cases, 4) Checking headers/status codes, 5) Testing authentication. Example: using supertest or axios.

External service strategies: 1) Use test doubles when needed, 2) Configure test endpoints, 3) Handle authentication, 4) Manage service state, 5) Handle network issues.

Test isolation methods: 1) Clean database between tests, 2) Reset service state, 3) Use transactions, 4) Implement proper teardown, 5) Handle shared resources.

Hooks are used for: 1) Setting up test environment, 2) Database preparation, 3) Service initialization, 4) Resource cleanup, 5) State management. Critical for test setup/teardown.

Async handling includes: 1) Using async/await, 2) Proper timeout configuration, 3) Handling promises, 4) Managing concurrent operations, 5) Error handling.

Service testing strategies: 1) Test service boundaries, 2) Verify data flow, 3) Test error conditions, 4) Handle service dependencies, 5) Test service lifecycle.

Data flow handling: 1) Test data transformations, 2) Verify state changes, 3) Test data consistency, 4) Handle data dependencies, 5) Manage data lifecycle.

Middleware testing: 1) Test request processing, 2) Verify middleware chain, 3) Test error handling, 4) Check modifications, 5) Test order dependencies.

Auth testing includes: 1) Test login processes, 2) Verify token handling, 3) Test permissions, 4) Check session management, 5) Test auth failures.

Transaction testing: 1) Test commit behavior, 2) Verify rollbacks, 3) Test isolation levels, 4) Handle nested transactions, 5) Test concurrent access.

Cache testing: 1) Verify cache hits/misses, 2) Test invalidation, 3) Check cache consistency, 4) Test cache policies, 5) Handle cache failures.

Event testing patterns: 1) Test event emission, 2) Verify handlers, 3) Test event order, 4) Check event data, 5) Test error events.

Migration testing: 1) Test upgrade paths, 2) Verify data integrity, 3) Test rollbacks, 4) Check data transforms, 5) Handle migration errors.

Queue testing: 1) Test message flow, 2) Verify processing, 3) Test error handling, 4) Check queue state, 5) Test concurrent access.

Config testing: 1) Test different environments, 2) Verify config loading, 3) Test defaults, 4) Check validation, 5) Test config changes.

Microservice patterns: 1) Test service mesh, 2) Verify service discovery, 3) Test resilience, 4) Check scaling, 5) Test service communication.

Contract testing: 1) Define service contracts, 2) Test API compatibility, 3) Verify schema changes, 4) Test versioning, 5) Handle contract violations.

Distributed testing: 1) Test network partitions, 2) Verify consistency, 3) Test recovery, 4) Handle latency, 5) Test scalability.

Consistency testing: 1) Test sync mechanisms, 2) Verify convergence, 3) Test conflict resolution, 4) Check data propagation, 5) Handle timing issues.

Resilience testing: 1) Test failure modes, 2) Verify recovery, 3) Test degraded operation, 4) Check failover, 5) Test self-healing.

Chaos testing: 1) Inject failures, 2) Test system response, 3) Verify recovery, 4) Check data integrity, 5) Test service resilience.

Scalability testing: 1) Test load handling, 2) Verify resource scaling, 3) Test performance, 4) Check bottlenecks, 5) Test capacity limits.

Boundary testing: 1) Test interfaces, 2) Verify protocols, 3) Test data formats, 4) Check error handling, 5) Test integration points.

Upgrade testing: 1) Test version compatibility, 2) Verify data migration, 3) Test rollback procedures, 4) Check system stability, 5) Test upgrade process.

Observability testing: 1) Test monitoring systems, 2) Verify metrics collection, 3) Test logging, 4) Check tracing, 5) Test alerting.