test(core): Use fake timers in promisebuffer tests to ensure deterministic behavior #18659
+46
−19
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Contributor
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.
|
Lms24
approved these changes
Jan 2, 2026
Comment on lines
108
to
110
| vi.useFakeTimers(); | ||
|
|
||
| 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 { |
Member
There was a problem hiding this comment.
l: Instead of the try/finally blocks, wdyt about using afterEach to reset timers?
Member
Author
There was a problem hiding this comment.
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
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