FrontendHaltTesting·Intermediate·Conceptual·1 min read
What does an end-to-end test verify that lower-level tests cannot?
Short interview answer
It verifies the whole system working together — frontend, backend, auth, database, third-party services — across real navigations and browser state. Bugs that only appear at an integration boundary, where each side passes its own tests, surface only here.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.