parallel/test-runner-coverage is flaky

[lpinca]

Test

test-runner-coverage

Platform

Windows ARM64

Console output

---
duration_ms: 22940.912
exitcode: 1
severity: fail
stack: "\u25B6 test coverage report\n \u2714 handles the inspector not being available\
 \ (2.0866ms)\n\u2714 test coverage report (3.7218ms)\n\u25B6 test tap coverage reporter\n\
 \ \u2714 coverage is reported and dumped to NODE_V8_COVERAGE if present (577.1212ms)\n\
 \ \u2714 coverage is reported without NODE_V8_COVERAGE present (851.508ms)\n\u2714\
 \ test tap coverage reporter (1429.2218ms)\n\u25B6 test spec coverage reporter\n\
 \ \u2714 coverage is reported and dumped to NODE_V8_COVERAGE if present (1419.2938ms)\n\
 \ \u2716 coverage is reported without NODE_V8_COVERAGE present (1175.4346ms)\n\
 \ AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:\n\
 \n assert(!findCoverageFileForPid(result.pid))\n\n at TestContext.<anonymous>\
 \ (d:\\workspace\\node-test-binary-windows-js-suites\\node\\test\\parallel\\test-runner-coverage.js:147:5)\n\
 \ at Test.runInAsyncScope (node:async_hooks:211:14)\n at Test.run\
 \ (node:internal/test_runner/test:930:25)\n at Test.start (node:internal/test_runner/test:829:17)\n\
 \ at TestContext.test (node:internal/test_runner/test:313:20)\n at\
 \ TestContext.<anonymous> (d:\\workspace\\node-test-binary-windows-js-suites\\node\\\
 test\\parallel\\test-runner-coverage.js:138:11)\n at async Test.run (node:internal/test_runner/test:931:9)\n\
 \ at async Test.processPendingSubtests (node:internal/test_runner/test:629:7)\
 \ {\n generatedMessage: true,\n code: 'ERR_ASSERTION',\n actual:\
 \ false,\n expected: true,\n operator: '=='\n }\n\n\u2716 test spec\
 \ coverage reporter (2595.3945ms)\n\u2714 single process coverage is the same with\
 \ --test (689.0507ms)\n\u2714 coverage is combined for multiple processes (625.1439ms)\n\
 \uFE63 coverage works with isolation=none (0.3688ms) # SKIP\n\u25B6 coverage reports\
 \ on lines, functions, and branches\n \u2714 does not include node_modules (0.316ms)\n\
 \ \u2714 reports on function coverage (0.1952ms)\n \u2714 reports on branch coverage\
 \ (0.2506ms)\n \u2714 reports on line coverage (0.2479ms)\n\u2714 coverage reports\
 \ on lines, functions, and branches (550.3549ms)\n\u2714 coverage with source maps\
 \ (577.2805ms)\n\u2714 coverage with source maps missing sources (411.9635ms)\n\u2714\
 \ coverage with ESM hook - source irrelevant (600.2435ms)\n\u2714 coverage with\
 \ ESM hook - source transpiled (607.2523ms)\n\u2714 coverage with excluded files\
 \ (304.553ms)\n\u2714 coverage with included files (302.6345ms)\n\u2714 coverage\
 \ with included and excluded files (285.25ms)\n\u2714 properly accounts for line\
 \ endings in source maps (398.9005ms)\n\u2714 correctly prints the coverage report\
 \ of files contained in parent directories (454.1338ms)\n\u2139 tests 25\n\u2139\
 \ suites 0\n\u2139 pass 22\n\u2139 fail 2\n\u2139 cancelled 0\n\u2139 skipped 1\n\
 \u2139 todo 0\n\u2139 duration_ms 9856.4836\n\n\u2716 failing tests:\n\ntest at\
 \ test\\parallel\\test-runner-coverage.js:138:11\n\u2716 coverage is reported without\
 \ NODE_V8_COVERAGE present (1175.4346ms)\n AssertionError [ERR_ASSERTION]: The\
 \ expression evaluated to a falsy value:\n\n assert(!findCoverageFileForPid(result.pid))\n\
 \n at TestContext.<anonymous> (d:\\workspace\\node-test-binary-windows-js-suites\\\
 node\\test\\parallel\\test-runner-coverage.js:147:5)\n at Test.runInAsyncScope\
 \ (node:async_hooks:211:14)\n at Test.run (node:internal/test_runner/test:930:25)\n\
 \ at Test.start (node:internal/test_runner/test:829:17)\n at TestContext.test\
 \ (node:internal/test_runner/test:313:20)\n at TestContext.<anonymous> (d:\\\
 workspace\\node-test-binary-windows-js-suites\\node\\test\\parallel\\test-runner-coverage.js:138:11)\n\
 \ at async Test.run (node:internal/test_runner/test:931:9)\n at async\
 \ Test.processPendingSubtests (node:internal/test_runner/test:629:7) {\n generatedMessage:\
 \ true,\n code: 'ERR_ASSERTION',\n actual: false,\n expected: true,\n \
 \ operator: '=='\n }"
...

Build links

• https://ci.nodejs.org/job/node-test-binary-windows-js-suites/30580/RUN_SUBSET=0,nodes=win11-arm64-COMPILED_BY-vs2022-arm64/testReport/junit/(root)/parallel/test_runner_coverage/

Additional information

No response

[StefanStojanovic]

Are we sure this is Windows-specific? I see other platforms failing this test in the reliability report too.

[lpinca]

Are we sure this is Windows-specific? I see other platforms failing this test in the reliability report too.

It may also be flaky on other platforms. The issue was opened with the first occurrence I noticed without further investigation.

[avivkeller]

For ease of readability, the formatted output is:

not ok 704 parallel/test-runner-coverage
 ---
 duration_ms: 22940.91200
 severity: fail
 exitcode: 1
 stack: |-
 â–¶ test coverage report
 ✔ handles the inspector not being available (2.0866ms)
 ✔ test coverage report (3.7218ms)
 â–¶ test tap coverage reporter
 ✔ coverage is reported and dumped to NODE_V8_COVERAGE if present (577.1212ms)
 ✔ coverage is reported without NODE_V8_COVERAGE present (851.508ms)
 ✔ test tap coverage reporter (1429.2218ms)
 â–¶ test spec coverage reporter
 ✔ coverage is reported and dumped to NODE_V8_COVERAGE if present (1419.2938ms)
 ✖ coverage is reported without NODE_V8_COVERAGE present (1175.4346ms)
 AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:
 
 assert(!findCoverageFileForPid(result.pid))
 
 at TestContext.<anonymous> (d:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-runner-coverage.js:147:5)
 at Test.runInAsyncScope (node:async_hooks:211:14)
 at Test.run (node:internal/test_runner/test:930:25)
 at Test.start (node:internal/test_runner/test:829:17)
 at TestContext.test (node:internal/test_runner/test:313:20)
 at TestContext.<anonymous> (d:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-runner-coverage.js:138:11)
 at async Test.run (node:internal/test_runner/test:931:9)
 at async Test.processPendingSubtests (node:internal/test_runner/test:629:7) {
 generatedMessage: true,
 code: 'ERR_ASSERTION',
 actual: false,
 expected: true,
 operator: '=='
 }
 
 ✖ test spec coverage reporter (2595.3945ms)
 ✔ single process coverage is the same with --test (689.0507ms)
 ✔ coverage is combined for multiple processes (625.1439ms)
 ï¹£ coverage works with isolation=none (0.3688ms) # SKIP
 â–¶ coverage reports on lines, functions, and branches
 ✔ does not include node_modules (0.316ms)
 ✔ reports on function coverage (0.1952ms)
 ✔ reports on branch coverage (0.2506ms)
 ✔ reports on line coverage (0.2479ms)
 ✔ coverage reports on lines, functions, and branches (550.3549ms)
 ✔ coverage with source maps (577.2805ms)
 ✔ coverage with source maps missing sources (411.9635ms)
 ✔ coverage with ESM hook - source irrelevant (600.2435ms)
 ✔ coverage with ESM hook - source transpiled (607.2523ms)
 ✔ coverage with excluded files (304.553ms)
 ✔ coverage with included files (302.6345ms)
 ✔ coverage with included and excluded files (285.25ms)
 ✔ properly accounts for line endings in source maps (398.9005ms)
 ✔ correctly prints the coverage report of files contained in parent directories (454.1338ms)
 ℹ tests 25
 ℹ suites 0
 ℹ pass 22
 ℹ fail 2
 ℹ cancelled 0
 ℹ skipped 1
 ℹ todo 0
 ℹ duration_ms 9856.4836
 
 ✖ failing tests:
 
 test at test\parallel\test-runner-coverage.js:138:11
 ✖ coverage is reported without NODE_V8_COVERAGE present (1175.4346ms)
 AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:
 
 assert(!findCoverageFileForPid(result.pid))
 
 at TestContext.<anonymous> (d:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-runner-coverage.js:147:5)
 at Test.runInAsyncScope (node:async_hooks:211:14)
 at Test.run (node:internal/test_runner/test:930:25)
 at Test.start (node:internal/test_runner/test:829:17)
 at TestContext.test (node:internal/test_runner/test:313:20)
 at TestContext.<anonymous> (d:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-runner-coverage.js:138:11)
 at async Test.run (node:internal/test_runner/test:931:9)
 at async Test.processPendingSubtests (node:internal/test_runner/test:629:7) {
 generatedMessage: true,
 code: 'ERR_ASSERTION',
 actual: false,
 expected: true,
 operator: '=='
 }
 ...

[lpinca]

I'm closing this because I don't see any recent failures in the reliability reports.

[panva]

This has recurred with the same assertion.

I checked the reliability reports from 2026-07-26 through 2026-08-26, deduplicated overlapping report windows by parent Jenkins job, and retained only PRs targeting main. The result is 7 unique PRs / 7 unique CI jobs.

Reports:

• https://github.com/nodejs/reliability/blob/main/reports/2026-08-15.md
• https://github.com/nodejs/reliability/blob/main/reports/2026-08-16.md
• https://github.com/nodejs/reliability/blob/main/reports/2026-08-17.md
• https://github.com/nodejs/reliability/blob/main/reports/2026-08-21.md
• https://github.com/nodejs/reliability/blob/main/reports/2026-08-24.md

The failures occur in several coverage subtests but converge on the assertion already recorded here:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:

 assert(!findCoverageFileForPid(result.pid))

Affected configurations include Windows 10/11/2022 x64, Windows 11 ARM64, RHEL 8/9 s390x, and AIX 7.2/7.3 Power9. This confirms that the flake is not Windows-specific.

This issue should be reopened, and the windows label should be removed or reconsidered. The current evidence supports PASS, FLAKY entries for Windows, Linux s390x, and AIX while the stale coverage-file behavior is investigated.