test: permit test-signalwrap to work without test runner

[Trott]

test/async-hooks/test-signalwrap.js passes with the test.py test runner
but fails if run directly with the node executable. Modify the test so
it passes in both cases.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/23994/

[bnoordhuis]

Can I suggest updating the comment to explain that the third signal event listener is the SIGWINCH handler that node installs when it thinks process.stdout is a tty?

It's still kind of fragile because there might be a second SIGWINCH handler for process.stderr, i.e., a total of 4.

[Trott]

@bnoordhuis Would the test be more robust by checking process.stdout.isTTY and process.stderr.isTTY rather than process.env.TEST_THREAD_ID?

[addaleax]

@Trott I think that’s better, yes. There is only one async hook per active signal (which should probably be considered a bug), so currently the number is 2 + (process.stdout.isTTY || process.stderr.isTTY), I think.

[addaleax]

LGTM with Ben’s suggestion

[Trott]

OK, all fixed up!

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/25392/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/25394/

[Trott]

Landed in 2d1b512