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MSW Mock Service Worker: CORS headers in handlers, Jest and Vitest integration, and Node versus browser
MSW intercepts at the network layer—add Access-Control-* in handlers when tests run in jsdom with real fetch.
1 min read
mswtestingcors
GraphQL handlers
GraphQL POST requests still trigger preflight when Content-Type is non-simple—mirror API behavior in tests.
Batching queries changes header signatures—keep CORS tests aligned with Apollo Client settings.
Storybook
Decorators that wrap MSW should not duplicate CORS headers already emitted by the dev server.
Chromatic snapshots cannot capture CORS—document expected headers in story parameters instead.