End-to-End Testing Overview
Explain how end-to-end testing with tools like Cypress or Playwright differs from unit/component testing and what it's meant to catch.
End-to-end (E2E) testing exercises a real, fully running application in an actual browser, driving it through genuine user interactions — clicking real buttons, filling real forms, navigating real URLs — and asserting on the real, rendered outcome, in sharp contrast to unit/component tests, which run in an isolated, synthetic test harness with mocked dependencies. Interviewers ask about this at a conceptual level to check that you understand where E2E testing fits in a broader testing strategy, not necessarily deep tool-specific API knowledge.
Unit tests are like a car factory testing each individual part (brakes, engine, seatbelts) on a bench in isolation; end-to-end tests are like taking the fully assembled car out for an actual test drive on a real road to confirm everything genuinely works together as a whole vehicle.