You opened Cursor. You typed "build me a booking app." Forty-five minutes later, you have something that runs. The login works. The calendar mostly works. You ship it. Then a friend tries it and the date picker goes blank on iOS. Another user finds that hitting back after a failed payment leaves the form locked. Someone else can't sign up because their email has a plus sign in it. Welcome to the gap nobody talks about in the vibe coding era: AI-built apps are easier to ship than ever, and exactly as buggy as you'd expect from code you didn't fully read. Traditional testing — the unit tests, the integration tests, the Selenium suites — assumes you have time, expertise, and patience to write them. Vibe coders have none of those. So the apps go out untested. This post is about the shift that's quietly happening: AI testing tools that act like real users, find real bugs in your AI-built app, and never ask you to write a line of test code. Why traditional testing fails vibe coders Selenium is from 2004.…