test: address flaky worker test

[Trott]

Move test/parallel/test-worker-message-port-transfer-closed.js to
sequential to avoid race condition with setTimeout() at end of test.

Fixes: #21892

/cc @TimothyGu

Checklist

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

[nodejs-github-bot]

@Trott build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/316/pipeline

[Trott]

CI: https://ci.nodejs.org/job/node-test-pull-request/15953/

[addaleax]

Hm – if I may offer an alternative?

diff --git a/test/parallel/test-worker-message-port-transfer-closed.js b/test/parallel/test-worker-message-port-transfer-closed.js
index 435a3789fca7..e3a13bfcbfe9 100644
--- a/test/parallel/test-worker-message-port-transfer-closed.js
+++ b/test/parallel/test-worker-message-port-transfer-closed.js
@@ -50,5 +50,9 @@ testSingle(port1, port2);
 port2.close(common.mustCall(testBothClosed));
 testBothClosed();
 
-setTimeout(common.mustNotCall('The communication channel is still open'),
-           common.platformTimeout(1000)).unref();
+function tickUnref(n, fn) {
+  if (n === 0) return fn();
+  setImmediate(tickUnref, n-1, fn).unref();
+}
+
+tickUnref(10, common.mustNotCall('The communication channel is still open'));

This removes the timeout too, but we can keep the test in parallel this way…

[Trott]

@addaleax SGTM. Do you want to open a PR for that change? Or would you prefer I put it into this one and move it back to parallel here? I'm fine either way, of course.

[addaleax]

@Trott either one is fine :)

[Trott]

Updated with @addaleax's suggestion.

Re-running stress test to see if this PR passes: https://ci.nodejs.org/job/node-stress-single-test/1970/nodes=freebsd10-64/console

Same stress test failing on master: https://ci.nodejs.org/job/node-stress-single-test/1967/nodes=freebsd10-64/console

[addaleax]

😉

[Trott]

CI: https://ci.nodejs.org/job/node-test-pull-request/15985/

[Trott]

CI again: https://ci.nodejs.org/job/node-test-pull-request/15991/

[Trott]

Landed in f93a19b