End to End Test
In plain terms
Testing a complete user flow through the whole system.
Going deeper
End-to-end tests verify an entire workflow from the user's perspective across all integrated components, catching issues unit tests miss. They exercise the full stack.
Under the hood
High confidence but slow and brittle; sit atop the test pyramid and should be used sparingly.
Examples
Cypress, Playwright, Selenium, user-flow testing, checkout flows.
Think of it like...
Like test-driving a finished car on a real road rather than checking parts separately.