End-to-end test (E2E)

A test that drives the full application as a user would — through the UI, through the backend, against a real or near-real environment.

Example: A Playwright script that logs in, adds an item to a cart, and checks the order confirmation page.

In practice: High confidence when they pass, but slow, expensive to maintain, and notoriously flaky — most teams keep a small, stable E2E suite covering critical flows rather than trying to cover everything.

Debated: There's an ongoing debate about how much to invest in E2E vs. integration tests — Cypress and Playwright have made E2E more accessible, but the maintenance burden still causes teams to trim suites over time.

• often confused with Integration test