Registration & login testing checklist — with a Playwright autotest for every item
Login is the first screen a user sees and a favorite spot for production incidents. The "checklist item → how to automate it" format: user enumeration via identical error messages, password reset with a single-use token, logout and the back button, HttpOnly/Secure cookies via context.cookies(), sessions across two tabs, mocking 429 for lockout UI, the storageState pattern so you don't log in inside every test — and what parts of auth should never go into e2e.