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Playwright E2E tests: CORS behavior in Chromium, Firefox, and WebKit; service workers and bypass patterns
Playwright runs real browser stacks—your tests exercise true CORS, unlike mocked fetch in unit tests.
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playwrighte2ecors
Trace viewer
Inspect failed preflight steps in traces to distinguish CORS failures from slow backends.
HAR exports should redact Authorization headers before sharing CORS bug reports publicly.
Parallel shards
When sharding suites, keep per-shard API base URLs stable so Allow-Origin caches do not cross-contaminate.
Use project dependencies to run auth setup once before CORS-heavy SPAs.