test: fix test-child-process-pipe-dataflow

[MoLow]

Fixes: #48300

seems like something changed in the Windows machines causing wc to behave differently
changed from wc -c (count bytes) to wc -m (count characters).

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/52083/

[lpinca]

By the way the test passes with wc -c on GitHub Actions, so I think it is an issue with our Windows machines or the tools used there.

[MoLow]

By the way the test passes with wc -c on GitHub Actions, so I think it is an issue with our Windows machines or the tools used there.

Yep. passed by me locally on a windows vm as well

[aduh95]

And it used to pass on Jenkins until a few days ago

[MoLow]

this fix only fixes the issue for some windows versions: https://ci.nodejs.org/job/node-test-binary-windows-js-suites/21245/

[bricss]

As an option for quickfix 🩹 it would be the use of wc -cm and match with one of the output columns 🙂

[MoLow]

I think we can implement wc ourselves, it will be less hacky than passing unexpected flags:
`node -p "process.stdin.toArray().then(arr => console.log(arr.join("").length))"

[lpinca]

I think that invalidates the original intention of the test as we could do the same for cat and grep.

[MoLow]

Well I guess the best solution is to figure out why wc started returning these numbers on windows :|

[lpinca]

Or mark it flaky until we do :).

[bricss]

IMO, wc -cm with assert.match(wcBuf.trim(), new RegExp(String.raw`\b${ MB + 1 }\b`)) might do the trick 🤹