End-to-End Testing with Playwright/Cypress
Automated browser tests that simulate real user interactions through an actual, full application stack, providing the highest-confidence but slowest and most expensive layer of the testing pyramid.
End-to-end (E2E) testing simulates real user interactions — clicking buttons, filling out forms, navigating between pages — against a genuinely real, fully running instance of an application, typically driving an actual browser through tools like Playwright or Cypress, verifying that an entire user flow works correctly from the UI all the way through to the real backend and database, with nothing mocked or stubbed out anywhere in the chain. It sits at the top of the testing pyramid, offering the highest possible confidence that the system genuinely works as a real user would experience it, at the cost of being the slowest, most resource-intensive, and often most brittle layer to maintain.
End-to-end testing is like a full dress rehearsal of an entire theatrical production with the real cast, real costumes, real lighting, and a real live audience seated in the actual theater, versus a unit test which is more like one actor privately rehearsing a single line in front of a mirror — the dress rehearsal catches problems (a costume malfunction, a lighting cue firing at the wrong real moment) that rehearsing individual lines alone could never reveal, but you obviously can't afford to run a full dress rehearsal for every single line in the entire show.