Testing & Debugging Interview Questions

Jest and React Testing Library are recommended for unit and integration testing. Cypress or Playwright for end-to-end testing. Vitest gaining popularity for faster test execution. Built-in Next.js testing support.

Configure jest.config.js for Next.js. Set up environment and transforms. Handle module mocking. Support TypeScript testing. Default configuration available with next/jest.

Use React Testing Library to render pages. Test page components. Handle data fetching. Support routing tests. Test page lifecycle.

Use Chrome DevTools or VS Code debugger. Set breakpoints. Inspect component state. Handle error tracing. Support source maps.

Mock HTTP requests. Test API endpoints. Handle response validation. Support API testing. Implement test scenarios.

Captures component output. Compares against stored snapshots. Detects UI changes. Support snapshot updates. Handle snapshot maintenance.

Use Node.js debugger. Handle server breakpoints. Inspect server state. Support server-side debugging. Implement logging.

Test individual components/functions. Handle isolated testing. Support test coverage. Implement unit test cases. Handle component logic.

Create test fixtures. Handle mock data. Support test databases. Implement data generation. Handle test state.

Mock fetch requests. Handle async testing. Support data mocking. Implement fetch testing. Handle response simulation.

Test component interactions. Handle feature testing. Support workflow testing. Implement integration scenarios. Handle component communication.

Use React DevTools Profiler. Handle performance monitoring. Support optimization. Implement performance debugging. Handle bottlenecks.

Mock authentication state. Handle protected routes. Support auth testing. Implement auth scenarios. Handle user sessions.

Configure coverage reporting. Handle coverage goals. Support coverage analysis. Implement coverage tracking. Handle code coverage.

Create middleware tests. Handle request processing. Support middleware testing. Implement test scenarios. Handle middleware chain.

Use Cypress or Playwright. Handle user flows. Support browser testing. Implement test scenarios. Handle end-to-end workflows.

Handle route debugging. Support navigation testing. Implement route testing. Handle path resolution. Debug routing logic.

Test error scenarios. Handle error boundaries. Support error testing. Implement error cases. Handle error recovery.

Test state changes. Handle state updates. Support state testing. Implement state scenarios. Handle state logic.

Create complex test scenarios. Handle advanced cases. Support pattern testing. Implement testing strategies. Handle edge cases.

Implement CI/CD testing. Handle automated tests. Support test pipelines. Implement automation strategies. Handle continuous testing.

Test performance metrics. Handle load testing. Support stress testing. Implement performance scenarios. Handle optimization testing.

Implement security tests. Handle vulnerability testing. Support penetration testing. Implement security scenarios. Handle security validation.

Track test execution. Handle test analytics. Support monitoring tools. Implement monitoring strategies. Handle test metrics.

Create test documentation. Handle documentation updates. Support example tests. Implement documentation strategies. Handle maintenance.

Use visual regression testing. Handle UI testing. Support screenshot testing. Implement visual validation. Handle visual comparison.

Configure test environments. Handle environment setup. Support environment isolation. Implement environment management. Handle configurations.

Set up continuous testing. Handle automated runs. Support test pipelines. Implement continuous strategies. Handle test automation.

Maintain test suites. Handle test updates. Support test refactoring. Implement maintenance strategies. Handle test debt.