fix(backport): apply body delay before the response end#2969
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This fixes a regression where `delayBody(N)` no longer makes a body look
slow to the caller. Read timeouts on the response stream are expected to
fire when N exceeds them, but in v14 the @mswjs/interceptors-based
pipeline drains the response body before delivering the response event.
Pausing the body source (the v13 mechanism) ended up delaying the
*whole* response — response, data, and end events all moved to
`+delayBodyInMs`, indistinguishable from a slow connection.
Two coordinated pieces fix it:
1. `lib/playback_interceptor.js`: drop the pause/resume mechanism and
gate only the end-of-response push (`response.push(null)`) on
`delayBodyInMs`. Schedule that gate inside `respond()` so
`delay({ head, body })` continues to compound — head defers the
response event, body then defers the end signal by an additional
`body` ms. Reply callbacks like `replyWithFile` hand back an
explicitly-paused `fs.createReadStream`, so call
`bodyAsStream.resume()` to ensure the body flows.
2. `tests/got/test_delay.js`: the two tests that asserted timing on the
first `data` event are updated to assert on the `end` event,
matching the new (and intended) semantics.
Refs: nock#2867
Fixes: nock#2863
mikicho
approved these changes
Apr 30, 2026
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🎉 This PR is included in version 14.0.14 🎉 The release is available on: Your semantic-release bot 📦🚀 |
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This fixes a regression where
delayBody(N)no longer makes a body look slow to the caller. Read timeouts on the response stream are expected to fire when N exceeds them, but in v14 the @mswjs/interceptors-based pipeline drains the response body before delivering the response event. Pausing the body source (the v13 mechanism) ended up delaying the whole response — response, data, and end events all moved to+delayBodyInMs, indistinguishable from a slow connection.Two coordinated pieces fix it:
lib/playback_interceptor.js: drop the pause/resume mechanism and gate only the end-of-response push (response.push(null)) ondelayBodyInMs. Schedule that gate insiderespond()sodelay({ head, body })continues to compound — head defers the response event, body then defers the end signal by an additionalbodyms. Reply callbacks likereplyWithFilehand back an explicitly-pausedfs.createReadStream, so callbodyAsStream.resume()to ensure the body flows.tests/got/test_delay.js: the two tests that asserted timing on the firstdataevent are updated to assert on theendevent, matching the new (and intended) semantics.Refs: #2867
Fixes: #2863