`expect(x).toBeInstanceOf(Blob)` asks which realm constructed the body, not
whether there is one. Under jsdom the ambient `Blob` is jsdom's class, while
`Response.blob()` hands back node's own on Node 22 and jsdom's on Node 24 — so
both assertions passed locally and failed on the server gate, for a reason that
says nothing about the code under test. `.text()` is the mirror image: jsdom's
Blob does not implement it, so reading the bytes back is green on 22 and red on
24.
Both now assert the brand (`[object Blob]`, agreed by both realms) plus size and
type. Mutation-checked in node:22-bookworm: dropping `{ raw: true }` from
`debugExport` still turns the test red, so the repaired assertion still catches
the defect it was written for.
core.test.ts also stops building its Response from a jsdom `Blob`: on Node 22
undici does not recognise it as a body and stringifies it, so the fixture's body
was the 13 bytes of "[object Blob]" rather than the zip header. A string body is
what the sibling test already used.
peter
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