test(core): Use fake timers in promisebuffer tests to ensure deterministic behavior #18659
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node-overhead report 🧳Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
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Lms24
approved these changes
Jan 2, 2026
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| vi.useFakeTimers(); | ||
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| const p1 = vi.fn(() => new Promise(resolve => setTimeout(resolve, 1))); | ||
| const p2 = vi.fn(() => new Promise(resolve => setTimeout(resolve, 1))); | ||
| const p3 = vi.fn(() => new Promise(resolve => setTimeout(resolve, 1))); | ||
| const p4 = vi.fn(() => new Promise(resolve => setTimeout(resolve, 1))); | ||
| const p5 = vi.fn(() => new Promise(resolve => setTimeout(resolve, 1))); | ||
| try { |
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l: Instead of the try/finally blocks, wdyt about using afterEach to reset timers?
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Right, I agree. I did it like this because we only use fake timers in these two tests (there are still real timeouts in other tests), but should be fine to just always use it and it's a bit cleaner
This was referenced Jan 9, 2026
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The
drain()tests inpromisebuffer.test.tswere flaky. The tests currently rely on real timers with small increments to test the timeout parameter ofdrain(). This can lead to race conditions between promise resolution and drain timeout.This PR switches to Vitest's fake timers, giving us deterministic control over time progression and should thereby eliminate the race condition.
Closes #18642