test: deflake test-runner-coverage by christianaurichzm · Pull Request #65728 · nodejs/node

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

christianaurichzm · 2026-09-01T23:44:51Z

test-runner-coverage is marked flaky on Windows, Linux s390x and AIX. Every recorded failure is the same assertion:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value: assert(!findCoverageFileForPid(result.pid))

Cause

The two subtests that pass NODE_V8_COVERAGE: tmpdir.path leave a coverage-<pid>-<ts>-<n>.json file behind, and tmpdir.refresh() only runs once, at the top of the file. The nine later checks spawn without NODE_V8_COVERAGE, so their coverage goes to the private mkdtemp directory that setupCoverage() creates and cleanup() removes, never to the test tmpdir. findCoverageFileForPid() keys only on the pid, so a match can only come from that stale file, once the OS hands the same pid to a later child.

Reproduction

Forcing pid reuse inside a pid namespace reproduces it on Linux x64. Pushing the cursor past RESERVED_PIDS makes the kernel allocate cyclically within [300, pid_max), a window this test wraps through several times:

unshare -rpf --mount-proc bash -ec ' echo 350 > /proc/sys/kernel/pid_max cat /proc/sys/kernel/pid_max # verify the requested value took effect for i in $(seq 1 320); do /bin/true; done out/Release/node test/parallel/test-runner-coverage.js'

	result
without the patch	40/40 runs failed
with the patch	0/40 runs failed

tools/test.py --repeat=24 -J parallel/test-runner-coverage passes on a normal Linux x64 run either way.

Fix

Refresh the tmpdir from an after() hook on each subtest that dumps into it. The hook rather than a trailing call matters: if an assertion in one of those subtests fails, a trailing cleanup is skipped and the stale file turns every later check into a second, misleading failure. Same forced pid reuse, with the failure injected into the last dumping subtest:

	cascading failures
cleanup at end of subtest	20/20 runs
cleanup in `after()`	0/20 runs

This also drops the PASS, FLAKY entries added in #65562 as a stopgap "while the stale coverage-file behavior is investigated"; with the stale file gone that failure path is removed, and keeping the entries would hide a regression
on those platforms.

Needs a full CI run to reach the affected configurations. The GitHub Actions Windows coverage job sets NODE_V8_COVERAGE for the test step, so it does not exercise this path.

Fixes: #55154

The subtests that set NODE_V8_COVERAGE leave a coverage-<pid>-*.json file in the test tmpdir, and nothing removes it. The later subtests spawn without NODE_V8_COVERAGE, so their coverage goes to a private mkdtemp directory that is removed on cleanup rather than to the test tmpdir. A match in findCoverageFileForPid(result.pid) can therefore only come from a stale file whose pid has been reused, which is why the failures are only reported on platforms that recycle pids quickly. Refresh the tmpdir from an after() hook on each subtest that dumps into it, so a failure in one of them cannot leave the file behind and turn every later check into a second, misleading failure. Drop the flaky designations. Fixes: nodejs#55154 Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>

nodejs-github-bot · 2026-09-01T23:44:56Z

Review requested:

@nodejs/test_runner

codecov · 2026-09-02T01:24:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (f9ab994) to head (4d8c8c3).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #65728 +/- ##
==========================================
+ Coverage 90.07% 90.11% +0.03% 
==========================================
Files 754 754 Lines 256395 256395 Branches 48494 48523 +29 ==========================================
+ Hits 230947 231044 +97 + Misses 16563 16479 -84 + Partials 8885 8872 -13

see 32 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

nodejs-github-bot · 2026-09-02T06:39:51Z

CI: https://ci.nodejs.org/job/node-test-pull-request/76872/

trivikr · 2026-09-02T07:02:47Z

Stress tests:

main: https://ci.nodejs.org/job/node-stress-single-test/883/ 🔴
pr: https://ci.nodejs.org/job/node-stress-single-test/884/ 🟢

EDIT: The failure in main is unrelated. PR stress test is successful though.

nodejs-github-bot added needs-ci PRs that need a full CI run. test Issues and PRs related to Node.js core tests and test infrastructure. labels Sep 1, 2026

atlowChemi approved these changes Sep 2, 2026
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panva added the author ready PRs with CI started, the required approvals, and no outstanding review comments. label Sep 2, 2026

github-actionsBot removed the request-ci Add this label to start a Jenkins CI on a PR. label Sep 2, 2026

trivikr added the flaky-test Issues and PRs involving tests that fail intermittently in CI. label Sep 2, 2026

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