test: fix race condition in watch mode tests #61615
Open
+30
−12
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
nodejs-github-bot
added
needs-ci
The watch mode tests using runInBackground() had a race condition where stdout "Failed running" message could arrive before stderr was fully collected, causing assertions on stderr content to fail with empty strings. Fix by waiting for stderr 'data' event if stderr is empty when "Failed running" is detected. This is an event-driven approach rather than timing-based. Refs: nodejs/reliability#1450
mcollina
force-pushed
the
fix-flaky-test-watch-mode-restart-esm-loading-error
branch
from
b6243b5 to
db115c1
Compare
MoLow
approved these changes
Feb 1, 2026
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #61615 +/- ##
==========================================
- Coverage 89.76% 89.74% -0.03%
==========================================
Files 673 673
Lines 203945 203945
Branches 39191 39189 -2
==========================================
- Hits 183076 183030 -46
- Misses 13198 13237 +39
- Partials 7671 7678 +7 🚀 New features to boost your workflow:
|
github-actions
bot
removed
the
request-ci
Collaborator
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
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Outdated suggestions cannot be applied.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.
Summary
Fixes race condition in watch mode tests that caused intermittent failures.
Problem
The watch mode tests using
runInBackground()had a race condition where the stdout "Failed running" message could arrive before stderr was fully collected, causing assertions on stderr content to fail with empty strings.Solution
When "Failed running" is detected in stdout and stderr is empty, wait for the stderr 'data' event before resolving the promise. This is an event-driven approach rather than timing-based.
Verification
test-watch-mode-restart-esm-loading-error.mjs: 200 runs, 0 failurestest-watch-mode.mjs: 50 runs, 0 failuresRefs: nodejs/reliability#1450