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test: hold each watcher probe state longer than a poll interval
Vladimir Sheremet
(Jul 27, 2026, 3:09 PM +0200)
007f50dc
bfa35002
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-6
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test/test-utils/index.ts
+24
-6
test/test-utils/index.ts
···
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const process_ = process
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// Polling interval of the file watcher in spawned watch-mode instances. The
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// watcher-ready probe derives its timing from it: each probe state must
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// outlive a full poll cycle, or the poller can keep sampling the state that
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// matches its baseline and never observe a difference.
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const WATCH_POLL_INTERVAL = 100
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export function createConsole({ tty, std }: { tty?: boolean; std?: 'inherit' } = {}) {
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const stdout = new Writable({
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write(chunk, __, callback) {
···
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// misses change events, so enforce polling for consistency
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// https://github.com/vitejs/vite/blob/b723a753ced0667470e72b4853ecda27b17f546a/playground/vitestSetup.ts#L211
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usePolling: true,
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interval: 100,
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interval: WATCH_POLL_INTERVAL,
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...viteConfig.server?.watch,
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},
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...viteConfig?.server,
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// verify end-to-end: keep cycling a probe file in the root until the watcher
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// reports it. The probe is recreated rather than rewritten because a creation
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// folded into the initial scan of the file AND its directory leaves nothing to
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// rescan; deleting and recreating it bumps the directory mtime every cycle, so
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// a live directory poller always sees a difference, and any probe event
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// (`add`, `change` or `unlink`) proves delivery.
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// rescan; alternating present/absent guarantees the current state differs from
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// whichever state the poller's baseline captured, and any probe event (`add`,
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// `change` or `unlink`) proves delivery. Each state is held for multiple poll
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// intervals: on a loaded runner, a cycle as fast as the poll interval aliases
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// with it — every rescan can land when the probe is back in the state matching
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// the poller's baseline, and no event ever fires.
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//
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// The scan can also surface writes made by the PREVIOUS test (an `afterEach`
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// restoring a fixture right before this instance started) as fresh change
···
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}
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watcher.on('all', onWatcherEvent)
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try {
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const holdProbeState = async () => {
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const stateEnd = Date.now() + WATCH_POLL_INTERVAL * 2.5
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while (Date.now() < stateEnd) {
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if (probeSeen) {
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return
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}
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await new Promise(resolve => setTimeout(resolve, 25))
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}
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}
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while (true) {
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if (probeSeen) {
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break
···
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)
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}
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fs.writeFileSync(probe, `${Date.now()}`, 'utf-8')
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await new Promise(resolve => setTimeout(resolve, 50))
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await holdProbeState()
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if (probeSeen) {
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break
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}
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fs.rmSync(probe, { force: true })
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await new Promise(resolve => setTimeout(resolve, 50))
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await holdProbeState()
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}
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while (Date.now() - lastEventAt < 200 && Date.now() < deadline) {