A test that walks the whole user journey through the real interface, from the first page to the final result, exactly as a customer would.
E2E stands for end-to-end. Instead of checking each part alone, the test opens a browser and behaves like a real customer: it enters the site, searches for a product, adds it to the cart, fills in the address and reaches the confirmation page. If the whole journey succeeds, it means the interface, the logic and the database work together, not just separately.
Each part can work on its own while the journey fails where they meet, and this is the kind of test that catches it. It is also the closest to what a business owner cares about: can the customer buy? Because it works from the interface, it needs no access to the system's code, which is why Fanann's QA Engineer can test, in a real browser, any site whose address you give it, even one not built in Fanann. Practical tip: these tests are slower than others, so write them only for the journeys that bring in money or customers, and leave small details to faster checks.