Silent Failures in Playwright: When Your Tests Pass But Your App Fails

Playwright's convenient auth APIs hide critical traps that silently sabotage test reliability—storageState preserves only cookies and localStorage, not sessionStorage where many SPAs store JWTs, causing tests to run unauthenticated while appearing to pass. Skipping auth verification during setup can ship false-positive tests into CI that mask real bugs, making it essential to understand these hidden failure modes and implement proper setup patterns before relying on full-stack tests for production confidence.