Why is end-to-end testing used? Can it be bypassed?

End-to-end (E2E) testing verifies the operation of the entire system as a whole — from the user interface to the database and back. Its goal is to ensure that all components interact correctly and that the user scenario is executed without errors.

While E2E tests can be omitted, doing so increases the risk of missing critical bugs that only manifest during the integration of all system parts. E2E tests are especially important for complex applications with many interdependent components and business logic.

Example: in an online store, an E2E test will check that a user can add a product to the cart, place an order, and receive confirmation — all steps together, not separately.